This file is indexed.

/usr/lib/python3/dist-packages/astLib/astPlots.py is in python3-astlib 0.10.0-1.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

   1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
"""module for producing astronomical plots

(c) 2007-2016 Matt Hilton 

U{http://astlib.sourceforge.net}

This module provides the matplotlib powered ImagePlot class, which is designed to be flexible. 
ImagePlots can have RA, Dec. coordinate axes, contour overlays, and have objects marked in them, 
using WCS coordinates. RGB plots are supported too.

@var DEC_TICK_STEPS: Defines the possible coordinate label steps on the delination axis in
sexagesimal mode. Dictionary format: {'deg', 'unit'}
@type DEC_TICK_STEPS: dictionary list

@var RA_TICK_STEPS: Defines the possible coordinate label steps on the right ascension axis in
sexagesimal mode. Dictionary format: {'deg', 'unit'}
@type RA_TICK_STEPS: dictionary list

@var DECIMAL_TICK_STEPS: Defines the possible coordinate label steps on both coordinate axes in
decimal degrees mode.
@type DECIMAL_TICK_STEPS: list

@var DEG: Variable to stand in for the degrees symbol.
@type DEG: string

@var PRIME: Variable to stand in for the prime symbol.
@type PRIME: string

@var DOUBLE_PRIME: Variable to stand in for the double prime symbol.
@type DOUBLE_PRIME: string

"""

import math
from . import astImages
from . import astWCS
from . import astCoords
import numpy
import pyfits
from scipy import interpolate
import pylab
import matplotlib.patches as patches
import sys

# Handle unicode python 2 and 3
if sys.version < '3':
    import codecs
    def u(x):
        return codecs.unicode_escape_decode(x)[0]
else:
    def u(x):
        return x
    
DEC_TICK_STEPS=[{'deg': 1.0/60.0/60.0,  'unit': "s"}, 
                {'deg': 2.0/60.0/60.0,  'unit': "s"},
                {'deg': 5.0/60.0/60.0,  'unit': "s"}, 
                {'deg': 10.0/60.0/60.0, 'unit': "s"},
                {'deg': 30.0/60.0/60.0, 'unit': "s"},
                {'deg': 1.0/60.0,       'unit': "m"},
                {'deg': 2.0/60.0,       'unit': "m"},
                {'deg': 5.0/60.0,       'unit': "m"},
                {'deg': 15.0/60.0,      'unit': "m"},
                {'deg': 30.0/60.0,      'unit': "m"}, 
                {'deg': 1.0,            'unit': "d"},
                {'deg': 2.0,            'unit': "d"},
                {'deg': 4.0,            'unit': "d"},
                {'deg': 5.0,            'unit': "d"},
                {'deg': 10.0,           'unit': "d"},
                {'deg': 20.0,           'unit': "d"},
                {'deg': 30.0,           'unit': "d"}]

RA_TICK_STEPS=[ {'deg': (0.5/60.0/60.0/24.0)*360.0,  'unit': "s"},
                {'deg': (1.0/60.0/60.0/24.0)*360.0,  'unit': "s"},
                {'deg': (2.0/60.0/60.0/24.0)*360.0,  'unit': "s"}, 
                {'deg': (4.0/60.0/60.0/24.0)*360.0,  'unit': "s"}, 
                {'deg': (5.0/60.0/60.0/24.0)*360.0,  'unit': "s"}, 
                {'deg': (10.0/60.0/60.0/24.0)*360.0, 'unit': "s"},
                {'deg': (20.0/60.0/60.0/24.0)*360.0, 'unit': "s"},
                {'deg': (30.0/60.0/60.0/24.0)*360.0, 'unit': "s"},
                {'deg': (1.0/60.0/24.0)*360.0,       'unit': "m"},
                {'deg': (2.0/60.0/24.0)*360.0,       'unit': "m"},
                {'deg': (5.0/60.0/24.0)*360.0,       'unit': "m"},
                {'deg': (10.0/60.0/24.0)*360.0,      'unit': "m"},
                {'deg': (20.0/60.0/24.0)*360.0,      'unit': "m"},
                {'deg': (30.0/60.0/24.0)*360.0,      'unit': "m"}, 
                {'deg': (1.0/24.0)*360.0,            'unit': "h"},
                {'deg': (3.0/24.0)*360.0,            'unit': "h"},
                {'deg': (6.0/24.0)*360.0,            'unit': "h"},
                {'deg': (12.0/24.0)*360.0,           'unit': "h"}]

DECIMAL_TICK_STEPS=[0.001, 0.0025, 0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1.0, 2.0, 2.5, 5.0, 10.0, 30.0, 90.0]

DEG = u("\N{DEGREE SIGN}")
PRIME = "$^\prime$"
DOUBLE_PRIME = "$^{\prime\prime}$"

#---------------------------------------------------------------------------------------------------
class ImagePlot:
    """This class describes a matplotlib image plot containing an astronomical image with an
    associated WCS.
    
    Objects within the image boundaries can be marked by passing their WCS coordinates to 
    L{ImagePlot.addPlotObjects}.
    
    Other images can be overlaid using L{ImagePlot.addContourOverlay}.
    
    For images rotated with North at the top, East at the left (as can be done using
    L{astImages.clipRotatedImageSectionWCS} or L{astImages.resampleToTanProjection}, WCS coordinate
    axes can be plotted, with tick marks set appropriately for the image size. Otherwise, a compass 
    can be plotted showing the directions of North and East in the image.

    RGB images are also supported.
    
    The plot can of course be tweaked further after creation using matplotlib/pylab commands.
    
    """
    def __init__(self, imageData, imageWCS, axes = [0.1,0.1,0.8,0.8], \
        cutLevels = ["smart", 99.5], colorMapName = "gray", title = None, axesLabels = "sexagesimal", \
        axesFontFamily="serif", axesFontSize=12.0, RATickSteps="auto", decTickSteps="auto",
        colorBar = False, interpolation = "bilinear"):
        """Makes an ImagePlot from the given image array and astWCS. For coordinate axes to work, the
        image and WCS should have been rotated such that East is at the left, North is at the top
        (see e.g. L{astImages.clipRotatedImageSectionWCS}, or L{astImages.resampleToTanProjection}).
        
        If imageData is given as a list in the format [r, g, b], a color RGB plot will be made. However,
        in this case the cutLevels must be specified manually for each component as a list -
        i.e. cutLevels = [[r min, r max], [g min, g max], [b min, b max]]. In this case of course, the
        colorMap will be ignored. All r, g, b image arrays must have the same dimensions.
        
        Set axesLabels = None to make a plot without coordinate axes plotted.
        
        The axes can be marked in either sexagesimal or decimal celestial coordinates. If RATickSteps
        or decTickSteps are set to "auto", the appropriate axis scales will be determined automatically 
        from the size of the image array and associated WCS. The tick step sizes can be overidden. 
        If the coordinate axes are in sexagesimal format a dictionary in the format {'deg', 'unit'} is 
        needed (see L{RA_TICK_STEPS} and L{DEC_TICK_STEPS} for examples). If the coordinate axes are in
        decimal format, the tick step size is specified simply in RA, dec decimal degrees.
        
        @type imageData: numpy array or list
        @param imageData: image data array or list of numpy arrays [r, g, b]
        @type imageWCS: astWCS.WCS
        @param imageWCS: astWCS.WCS object
        @type axes: list
        @param axes: specifies where in the current figure to draw the finder chart (see pylab.axes)
        @type cutLevels: list
        @param cutLevels: sets the image scaling - available options:
            - pixel values: cutLevels=[low value, high value].
            - histogram equalisation: cutLevels=["histEq", number of bins ( e.g. 1024)]
            - relative: cutLevels=["relative", cut per cent level (e.g. 99.5)]
            - smart: cutLevels=["smart", cut per cent level (e.g. 99.5)]
        ["smart", 99.5] seems to provide good scaling over a range of different images.
        Note that for RGB images, cut levels must be specified manually i.e. as a list:
        [[r min, rmax], [g min, g max], [b min, b max]]
        @type colorMapName: string
        @param colorMapName: name of a standard matplotlib colormap, e.g. "hot", "cool", "gray"
        etc. (do "help(pylab.colormaps)" in the Python interpreter to see available options)
        @type title: string
        @param title: optional title for the plot
        @type axesLabels: string
        @param axesLabels: either "sexagesimal" (for H:M:S, D:M:S), "decimal" (for decimal degrees)
        or None (for no coordinate axes labels)
        @type axesFontFamily: string
        @param axesFontFamily: matplotlib fontfamily, e.g. 'serif', 'sans-serif' etc.
        @type axesFontSize: float
        @param axesFontSize: font size of axes labels and titles (in points)
        @type colorBar: bool
        @param colorBar: if True, plot a vertical color bar at the side of the image indicating the intensity
        scale.
        @type interpolation: string
        @param interpolation: interpolation to apply to the image plot (see the documentation for
                              the matplotlib.pylab.imshow command)
        
        """
                
        self.RADeg, self.decDeg=imageWCS.getCentreWCSCoords()
        self.wcs=imageWCS
        
        # Handle case where imageData is [r, g, b]
        if type(imageData) == list:
            if len(imageData) == 3:
                if len(cutLevels) == 3:
                    r=astImages.normalise(imageData[0], cutLevels[0])
                    g=astImages.normalise(imageData[1], cutLevels[1])
                    b=astImages.normalise(imageData[2], cutLevels[2])
                    rgb=numpy.array([r.transpose(), g.transpose(), b.transpose()])
                    rgb=rgb.transpose()
                    self.data=rgb
                    self.rgbImage=True
                else:
                    raise Exception("tried to create a RGB array, but cutLevels is not a list of 3 lists")

            else:
                raise Exception("tried to create a RGB array but imageData is not a list of 3 arrays")
        else:
            self.data=imageData
            self.rgbImage=False
        
        self.axes=pylab.axes(axes)
        self.cutLevels=cutLevels
        self.colorMapName=colorMapName
        self.title=title
        self.axesLabels=axesLabels
        self.colorBar=colorBar
        self.axesFontSize=axesFontSize
        self.axesFontFamily=axesFontFamily
        
        self.flipXAxis=False
        self.flipYAxis=False
                
        self.interpolation=interpolation
        
        if self.axesLabels != None:
            
            # Allow user to override the automatic coord tick spacing
            if self.axesLabels == "sexagesimal":
                if RATickSteps != "auto":
                    if type(RATickSteps) != dict or "deg" not in list(RATickSteps.keys()) \
                            or "unit" not in list(RATickSteps.keys()):
                        raise Exception("RATickSteps needs to be in format {'deg', 'unit'} for sexagesimal axes labels")
                if decTickSteps != "auto":
                    if type(decTickSteps) != dict or "deg" not in list(decTickSteps.keys()) \
                            or "unit" not in list(decTickSteps.keys()):
                        raise Exception("decTickSteps needs to be in format {'deg', 'unit'} for sexagesimal axes labels")
            elif self.axesLabels == "decimal":
                if RATickSteps != "auto":
                    if type(RATickSteps) != float:
                        raise Exception("RATickSteps needs to be a float (if not 'auto') for decimal axes labels")
                if decTickSteps != "auto":
                    if type(decTickSteps) != float:
                        raise Exception("decTickSteps needs to be a float (if not 'auto') for decimal axes labels")
            self.RATickSteps=RATickSteps
            self.decTickSteps=decTickSteps
        
            self.calcWCSAxisLabels(axesLabels = self.axesLabels)
        
        # this list stores objects to overplot, add to it using addPlotObjects()
        self.plotObjects=[] 
        
        # this list stores image data to overlay as contours, add to it using addContourOverlay()
        self.contourOverlays=[]
        
        self.draw()


    def draw(self):
        """Redraws the ImagePlot.
        
        """
        
        pylab.axes(self.axes)
        pylab.cla()
        
        if self.title != None:
            pylab.title(self.title)
        try:
            colorMap=pylab.cm.get_cmap(self.colorMapName)
        except AssertionError:
            raise Exception(self.colorMapName+"is not a defined matplotlib colormap.")
        
        if self.rgbImage == False:
            self.cutImage=astImages.intensityCutImage(self.data, self.cutLevels)
            if self.cutLevels[0]=="histEq":
                pylab.imshow(self.cutImage['image'],  interpolation=self.interpolation, origin='lower', cmap=colorMap)
            else:
                pylab.imshow(self.cutImage['image'],  interpolation=self.interpolation,  norm=self.cutImage['norm'], \
                            origin='lower', cmap=colorMap)
        else:
            pylab.imshow(self.data, interpolation="bilinear", origin='lower')
        
        if self.colorBar == True:
            pylab.colorbar(shrink=0.8)
        
        for c in self.contourOverlays:
            pylab.contour(c['contourData']['scaledImage'], c['contourData']['contourLevels'], 
                            colors=c['color'], linewidths=c['width'])
        
        for p in self.plotObjects:
            for x, y, l in zip(p['x'], p['y'], p['objLabels']):
                if p['symbol'] == "circle":
                    c=patches.Circle((x, y), radius=p['sizePix']/2.0, fill=False, edgecolor=p['color'], 
                                        linewidth=p['width'])
                    self.axes.add_patch(c)
                elif p['symbol'] == "box":
                    c=patches.Rectangle((x-p['sizePix']/2, y-p['sizePix']/2), p['sizePix'], p['sizePix'], 
                        fill=False, edgecolor=p['color'], linewidth=p['width'])
                    self.axes.add_patch(c)
                elif p['symbol'] == "cross":
                    pylab.plot([x-p['sizePix']/2, x+p['sizePix']/2], [y, y], linestyle='-', 
                        linewidth=p['width'], color= p['color'])
                    pylab.plot([x, x], [y-p['sizePix']/2, y+p['sizePix']/2], linestyle='-', 
                        linewidth=p['width'], color= p['color'])
                elif p['symbol'] == "diamond":
                    c=patches.RegularPolygon([x, y], 4, radius=p['sizePix']/2, orientation=0, 
                                            edgecolor=p['color'], fill=False, linewidth=p['width'])
                    self.axes.add_patch(c)
                if l != None:
                    pylab.text(x, y+p['sizePix']/1.5, l, horizontalalignment='center', \
                                fontsize=p['objLabelSize'], color=p['color'])
            
            if p['symbol'] == "compass":
                x=p['x'][0]
                y=p['y'][0]
                ra=p['RA'][0]
                dec=p['dec'][0]
                
                westPoint,eastPoint,southPoint,northPoint=astCoords.calcRADecSearchBox(ra, dec, p['sizeArcSec']/3600.0/2.0)
                northPix=self.wcs.wcs2pix(ra, northPoint)
                eastPix=self.wcs.wcs2pix(eastPoint, dec)
                                
                edx=eastPix[0]-x
                edy=eastPix[1]-y
                ndx=northPix[0]-x
                ndy=northPix[1]-y
                nArrow=patches.Arrow(x, y, ndx, ndy, edgecolor=p['color'], facecolor=p['color'], width=p['width'])
                eArrow=patches.Arrow(x, y, edx, edy, edgecolor=p['color'], facecolor=p['color'], width=p['width'])                
                self.axes.add_patch(nArrow)
                self.axes.add_patch(eArrow)
                pylab.text(x+ndx+ndx*0.2, y+ndy+ndy*0.2, "N", horizontalalignment='center', 
                                verticalalignment='center', fontsize=p['objLabelSize'], color=p['color'])
                pylab.text(x+edx+edx*0.2, y+edy+edy*0.2, "E", horizontalalignment='center', 
                                verticalalignment='center', fontsize=p['objLabelSize'], color=p['color'])

            if p['symbol'] == "scaleBar":
                x=p['x'][0]
                y=p['y'][0]
                ra=p['RA'][0]
                dec=p['dec'][0]
                
                westPoint,eastPoint,southPoint,northPoint=astCoords.calcRADecSearchBox(ra, dec, p['sizeArcSec']/3600.0/2.0)
                northPix=self.wcs.wcs2pix(ra, northPoint)
                eastPix=self.wcs.wcs2pix(eastPoint, dec)
                edx=eastPix[0]-x
                edy=eastPix[1]-y
                ndx=northPix[0]-x
                ndy=northPix[1]-y
                
                if p['style'] == "arrows":
                    eArrow=patches.Arrow(x, y, edx, edy, edgecolor=p['color'], facecolor=p['color'], width=p['width'])  
                    wArrow=patches.Arrow(x, y, -edx, edy, edgecolor=p['color'], facecolor=p['color'], width=p['width'])   
                    self.axes.add_patch(eArrow)
                    self.axes.add_patch(wArrow)
                elif p['style'] == "whiskers":
                    ewArrow=patches.FancyArrowPatch(posA = (x+edx, y), posB = (x-edx,y+edy), edgecolor=p['color'], facecolor=p['color'], linewidth = p['width'], arrowstyle = '|-|')  
                    self.axes.add_patch(ewArrow)
                
                # Work out label
                if p['scaleBarLabel'] == None:
                    scaleLabel=None
                    if p['sizeArcSec'] < 60.0:
                        scaleLabel="%.0f %s" % (p['sizeArcSec'], DOUBLE_PRIME)
                    elif p['sizeArcSec'] >= 60.0 and p['sizeArcSec'] <  3600.0:
                        scaleLabel="%.0f %s" % (p['sizeArcSec']/60.0, PRIME)
                    else:
                        scaleLabel="%.0f %s" % (p['sizeArcSec']/3600.0, DEG)
                else:
                    scaleLabel=p['scaleBarLabel']
                pylab.text(x, y+0.025*self.data.shape[1], scaleLabel, horizontalalignment='center', 
                           verticalalignment='center', fontsize=p['objLabelSize'], color=p['color'])
                                
        if self.axesLabels != None:
            pylab.xticks(self.ticsRA[0], self.ticsRA[1], weight='normal', family=self.axesFontFamily, \
                                    fontsize=self.axesFontSize)
            pylab.yticks(self.ticsDec[0], self.ticsDec[1], weight='normal', family=self.axesFontFamily, \
                                    fontsize=self.axesFontSize)
            pylab.xlabel(self.RAAxisLabel, family=self.axesFontFamily, fontsize=self.axesFontSize)
            pylab.ylabel(self.decAxisLabel, family=self.axesFontFamily, fontsize=self.axesFontSize)
        else:
            pylab.xticks([], [])
            pylab.yticks([], [])
            pylab.xlabel("")
            pylab.ylabel("")
        
        if self.flipXAxis == False:
            pylab.xlim(0, self.data.shape[1]-1)
        else:
            pylab.xlim(self.data.shape[1]-1, 0)
        if self.flipYAxis == False:
            pylab.ylim(0, self.data.shape[0]-1)
        else:
            pylab.ylim(self.data.shape[0]-1, 0)


    def addContourOverlay(self, contourImageData, contourWCS, tag, levels = ["linear", "min", "max", 5],
                             width = 1, color = "white", smooth = 0, highAccuracy = False):
        """Adds image data to the ImagePlot as a contour overlay. The contours can be removed using 
        L{removeContourOverlay}. If a contour overlay already exists with this tag, it will be replaced.
        
        @type contourImageData: numpy array
        @param contourImageData: image data array from which contours are to be generated
        @type contourWCS: astWCS.WCS
        @param contourWCS: astWCS.WCS object for the image to be contoured
        @type tag: string
        @param tag: identifying tag for this set of contours
        @type levels: list
        @param levels: sets the contour levels - available options:
            - values: contourLevels=[list of values specifying each level]
            - linear spacing: contourLevels=['linear', min level value, max level value, number
            of levels] - can use "min", "max" to automatically set min, max levels from image data
            - log spacing: contourLevels=['log', min level value, max level value, number of
            levels] - can use "min", "max" to automatically set min, max levels from image data
        @type width: int
        @param width: width of the overlaid contours
        @type color: string
        @param color: color of the overlaid contours, specified by the name of a standard
            matplotlib color, e.g., "black", "white", "cyan"
            etc. (do "help(pylab.colors)" in the Python interpreter to see available options)
        @type smooth: float
        @param smooth: standard deviation (in arcsec) of Gaussian filter for
            pre-smoothing of contour image data (set to 0 for no smoothing)
        @type highAccuracy: bool
        @param highAccuracy: if True, sample every corresponding pixel in each image; otherwise, sample
            every nth pixel, where n = the ratio of the image scales.
        
        """
                
        if self.rgbImage == True:
            backgroundData=self.data[:,:,0]
        else:
            backgroundData=self.data
        contourData=astImages.generateContourOverlay(backgroundData, self.wcs, contourImageData, \
                                              contourWCS, levels, smooth, highAccuracy = highAccuracy)
        
        alreadyGot=False
        for c in self.contourOverlays:
            if c['tag'] == tag:
                c['contourData']=contourData
                c['tag']=tag
                c['color']=color
                c['width']=width
                alreadyGot=True
                
        if alreadyGot == False:
            self.contourOverlays.append({'contourData': contourData, 'tag': tag, 'color': color, \
                                            'width': width})
        self.draw()

    
    def removeContourOverlay(self, tag):
        """Removes the contourOverlay from the ImagePlot corresponding to the tag.
        
        @type tag: string
        @param tag: tag for contour overlay in ImagePlot.contourOverlays to be removed
        
        """
        
        index=0
        for p in self.contourOverlays:
            if p['tag'] == tag:
                self.plotObjects.remove(self.plotObjects[index])
            index=index+1
        self.draw()
        
        
    def addPlotObjects(self, objRAs, objDecs, tag, symbol="circle", size=4.0, width=1.0, color="yellow",                                           
                                    objLabels = None, objLabelSize = 12.0):
        """Add objects with RA, dec coords objRAs, objDecs to the ImagePlot. Only objects that fall within 
        the image boundaries will be plotted.
        
        symbol specifies the type of symbol with which to mark the object in the image. The following
        values are allowed:
            - "circle"
            - "box"
            - "cross"
            - "diamond"
        
        size specifies the diameter in arcsec of the symbol (if plotSymbol == "circle"), or the width
        of the box in arcsec (if plotSymbol == "box")
        
        width specifies the thickness of the symbol lines in pixels
        
        color can be any valid matplotlib color (e.g. "red", "green", etc.)
        
        The objects can be removed from the plot by using removePlotObjects(), and then calling
        draw(). If the ImagePlot already has a set of plotObjects with the same tag, they will be 
        replaced.
        
        @type objRAs: numpy array or list
        @param objRAs: object RA coords in decimal degrees
        @type objDecs: numpy array or list
        @param objDecs: corresponding object Dec. coords in decimal degrees
        @type tag: string
        @param tag: identifying tag for this set of objects
        @type symbol: string
        @param symbol: either "circle", "box", "cross", or "diamond"
        @type size: float
        @param size: size of symbols to plot (radius in arcsec, or width of box)
        @type width: float
        @param width: width of symbols in pixels
        @type color: string
        @param color: any valid matplotlib color string, e.g. "red", "green" etc.
        @type objLabels: list
        @param objLabels: text labels to plot next to objects in figure
        @type objLabelSize: float
        @param objLabelSize: size of font used for object labels (in points)
        
        """
        
        pixCoords=self.wcs.wcs2pix(objRAs, objDecs)
        
        xMax=self.data.shape[1]
        yMax=self.data.shape[0]
        
        if objLabels == None:
            objLabels=[None]*len(objRAs)
            
        xInPlot=[]
        yInPlot=[]
        RAInPlot=[]
        decInPlot=[]
        labelInPlot=[]
        for p, r, d, l in zip(pixCoords, objRAs, objDecs, objLabels):
            if p[0] >= 0 and p[0] < xMax and p[1] >= 0 and p[1] < yMax:
                xInPlot.append(p[0])
                yInPlot.append(p[1])
                RAInPlot.append(r)
                decInPlot.append(d)
                labelInPlot.append(l)
        
        xInPlot=numpy.array(xInPlot)
        yInPlot=numpy.array(yInPlot)
        RAInPlot=numpy.array(RAInPlot)
        decInPlot=numpy.array(decInPlot)
        
        # Size of symbols in pixels in plot - converted from arcsec
        sizePix=(size/3600.0)/self.wcs.getPixelSizeDeg()
        
        alreadyGot=False
        for p in self.plotObjects:
            if p['tag'] == tag:
                p['x']=xInPlot
                p['y']=yInPlot
                p['RA']=RAInPlot
                p['dec']=decInPlot
                p['tag']=tag
                p['objLabels']=objLabels
                p['symbol']=symbol
                p['sizePix']=sizePix
                p['sizeArcSec']=size
                p['width']=width
                p['color']=color
                p['objLabelSize']=objLabelSize
                alreadyGot=True
        
        if alreadyGot == False:
            self.plotObjects.append({'x': xInPlot, 'y': yInPlot, 'RA': RAInPlot, 'dec': decInPlot,
                                'tag': tag, 'objLabels': labelInPlot, 'symbol': symbol, 
                                'sizePix': sizePix, 'width': width, 'color': color,
                                'objLabelSize': objLabelSize, 'sizeArcSec': size})
        self.draw()
        
        
    def removePlotObjects(self, tag):
        """Removes the plotObjects from the ImagePlot corresponding to the tag. The plot must be redrawn
        for the change to take effect.
        
        @type tag: string
        @param tag: tag for set of objects in ImagePlot.plotObjects to be removed
        
        """
        
        index=0
        for p in self.plotObjects:
            if p['tag'] == tag:
                self.plotObjects.remove(self.plotObjects[index])
            index=index+1
        self.draw()
  
        
    def addCompass(self, location, sizeArcSec, color = "white", fontSize = 12, \
                        width = 20.0):
        """Adds a compass to the ImagePlot at the given location ('N', 'NE', 'E', 'SE', 'S', 
        'SW', 'W', or 'NW'). Note these aren't directions on the WCS coordinate grid, they are 
        relative positions on the plot - so N is top centre, NE is top right, SW is bottom right etc.. 
        Alternatively, pixel coordinates (x, y) in the image can be given.
        
        @type location: string or tuple
        @param location: location in the plot where the compass is drawn:
            - string: N, NE, E, SE, S, SW, W or NW
            - tuple: (x, y)
        @type sizeArcSec: float
        @param sizeArcSec: length of the compass arrows on the plot in arc seconds
        @type color: string
        @param color: any valid matplotlib color string
        @type fontSize: float
        @param fontSize: size of font used to label N and E, in points
        @type width: float
        @param width: width of arrows used to mark compass
        
        """
        
        if type(location) == str:
            cRADeg, cDecDeg=self.wcs.getCentreWCSCoords()
            RAMin, RAMax, decMin, decMax=self.wcs.getImageMinMaxWCSCoords()
            westPoint,eastPoint,southPoint,northPoint=astCoords.calcRADecSearchBox(cRADeg, cDecDeg, sizeArcSec/3600.0/2.0)
            sizeRADeg=eastPoint-westPoint
            sizeDecDeg=northPoint-southPoint
            xSizePix=(sizeArcSec/3600.0)/self.wcs.getXPixelSizeDeg()
            ySizePix=(sizeArcSec/3600.0)/self.wcs.getYPixelSizeDeg()
            X=self.data.shape[1]
            Y=self.data.shape[0]
            xBufferPix=0.5*xSizePix
            yBufferPix=0.5*ySizePix
            cx, cy=self.wcs.wcs2pix(cRADeg, cDecDeg)
            foundLocation=False
            x=cy
            y=cx
            if self.wcs.isFlipped() == False:              
                if location.find("N") != -1:
                    y=Y-2*yBufferPix
                    foundLocation=True
                if location.find("S") != -1:
                    y=yBufferPix
                    foundLocation=True
                if location.find("E") != -1:
                    x=xBufferPix*2
                    foundLocation=True
                if location.find("W") != -1:
                    x=X-xBufferPix
                    foundLocation=True
            else:
                if location.find("S") != -1:
                    y=Y-2*yBufferPix
                    foundLocation=True
                if location.find("N") != -1:
                    y=yBufferPix
                    foundLocation=True
                if location.find("W") != -1:
                    x=xBufferPix*2
                    foundLocation=True
                if location.find("E") != -1:
                    x=X-xBufferPix
                    foundLocation=True
            if foundLocation == False:
                raise Exception("didn't understand location string for scale bar (should be e.g. N, S, E, W).")
            RADeg, decDeg=self.wcs.pix2wcs(x, y)
        elif type(location) == tuple or type(location) == list:
            x, y=location
            RADeg, decDeg=self.wcs.pix2wcs(x, y)
        else:
            raise Exception("didn't understand location for scale bar - should be string or tuple.")
        
        alreadyGot=False
        for p in self.plotObjects:
            if p['tag'] == "compass":
                p['x']=[x]
                p['y']=[y]
                p['RA']=[RADeg]
                p['dec']=[decDeg]
                p['tag']="compass"
                p['objLabels']=[None]
                p['symbol']="compass"
                p['sizeArcSec']=sizeArcSec
                p['width']=width
                p['color']=color
                p['objLabelSize']=fontSize
                alreadyGot=True
        
        if alreadyGot == False:
            self.plotObjects.append({'x': [x], 'y': [y], 'RA': [RADeg], 'dec': [decDeg],
                                'tag': "compass", 'objLabels': [None], 'symbol': "compass", 
                                'width': width, 'color': color,
                                'objLabelSize': fontSize, 'sizeArcSec': sizeArcSec})
        self.draw()


    def addScaleBar(self, location, sizeArcSec, color = "white", fontSize = 12, \
                        width = 20.0, label = None, style = "whiskers"):
        """Adds a scale bar to the ImagePlot at the given location ('N', 'NE', 'E', 'SE', 'S', 
        'SW', 'W', or 'NW'). Note these aren't directions on the WCS coordinate grid, they are 
        relative positions on the plot - so N is top centre, NE is top right, SW is bottom right etc.. 
        Alternatively, pixel coordinates (x, y) in the image can be given.
        
        @type location: string or tuple
        @param location: location in the plot where the compass is drawn:
            - string: N, NE, E, SE, S, SW, W or NW
            - tuple: (x, y)
        @type sizeArcSec: float
        @param sizeArcSec: scale length to indicate on the plot in arc seconds
        @type color: string
        @param color: any valid matplotlib color string
        @type fontSize: float
        @param fontSize: size of font used to label N and E, in points
        @type width: float
        @param width: width of arrow used to mark scale
        @type label: string
        @param label: overrides the displayed label if not None (if None, label is the angular size)
        @type style: string
        @param style: either "whiskers" or "arrows"
        
        """
        
        # Work out where the scale bar is going in WCS coords from the relative location given
        if type(location) == str:
            cRADeg, cDecDeg=self.wcs.getCentreWCSCoords()
            RAMin, RAMax, decMin, decMax=self.wcs.getImageMinMaxWCSCoords()
            westPoint,eastPoint,southPoint,northPoint=astCoords.calcRADecSearchBox(cRADeg, cDecDeg, sizeArcSec/3600.0/2.0)
            sizeRADeg=eastPoint-westPoint
            sizeDecDeg=northPoint-southPoint
            xSizePix=(sizeArcSec/3600.0)/self.wcs.getXPixelSizeDeg()
            ySizePix=(sizeArcSec/3600.0)/self.wcs.getYPixelSizeDeg()
            X=self.data.shape[1]
            Y=self.data.shape[0]
            xBufferPix=0.6*ySizePix
            yBufferPix=0.05*Y
            cx, cy=self.wcs.wcs2pix(cRADeg, cDecDeg)
            foundLocation=False
            x=cy
            y=cx
            if self.wcs.isFlipped() == False:
                if location.find("N") != -1:
                    y=Y-1.5*yBufferPix
                    foundLocation=True
                if location.find("S") != -1:
                    y=yBufferPix
                    foundLocation=True
                if location.find("E") != -1:
                    x=xBufferPix
                    foundLocation=True
                if location.find("W") != -1:
                    x=X-xBufferPix
                    foundLocation=True
            else:
                if location.find("S") != -1:
                    y=Y-1.5*yBufferPix
                    foundLocation=True
                if location.find("N") != -1:
                    y=yBufferPix
                    foundLocation=True
                if location.find("W") != -1:
                    x=xBufferPix
                    foundLocation=True
                if location.find("E") != -1:
                    x=X-xBufferPix
                    foundLocation=True
            if foundLocation == False:
                raise Exception("didn't understand location string for scale bar (should be e.g. N, S, E, W).")
            RADeg, decDeg=self.wcs.pix2wcs(x, y)
        elif type(location) == tuple or type(location) == list:
            x, y=location
            RADeg, decDeg=self.wcs.pix2wcs(x, y)
        else:
            raise Exception("didn't understand location for scale bar - should be string or tuple.")
        
        alreadyGot=False
        for p in self.plotObjects:
            if p['tag'] == "scaleBar":
                p['x']=[x]
                p['y']=[y]
                p['RA']=[RADeg]
                p['dec']=[decDeg]
                p['tag']="scaleBar"
                p['objLabels']=[None]
                p['symbol']="scaleBar"
                p['sizeArcSec']=sizeArcSec
                p['width']=width
                p['color']=color
                p['objLabelSize']=fontSize
                p['scaleBarLabel']=label
                p['style']=style
                alreadyGot=True
        
        if alreadyGot == False:
            self.plotObjects.append({'x': [x], 'y': [y], 'RA': [RADeg], 'dec': [decDeg],
                                'tag': "scaleBar", 'objLabels': [None], 'symbol': "scaleBar", 
                                'width': width, 'color': color,
                                'objLabelSize': fontSize, 'sizeArcSec': sizeArcSec,
                                'scaleBarLabel': label, 'style': style})
        self.draw()
                                

    def calcWCSAxisLabels(self, axesLabels = "decimal"):
        """This function calculates the positions of coordinate labels for the RA and Dec axes of the 
        ImagePlot. The tick steps are calculated automatically unless self.RATickSteps,
        self.decTickSteps are set to values other than "auto" (see L{ImagePlot.__init__}). 
        
        The ImagePlot must be redrawn for changes to be applied.
        
        @type axesLabels: string
        @param axesLabels: either "sexagesimal" (for H:M:S, D:M:S), "decimal" (for decimal degrees),
        or None for no coordinate axes labels
        
        """
        
        # Label equinox on axes
        equinox=self.wcs.getEquinox()
        if equinox<1984:
            equinoxLabel="B"+str(int(equinox))
        else:
            equinoxLabel="J"+str(int(equinox))
           
        self.axesLabels=axesLabels
        
        ticsDict=self.getTickSteps()
        
        # Manual override - note: no minor tick marks anymore, but may want to bring them back
        if self.RATickSteps != "auto":
            ticsDict['major']['RA']=self.RATickSteps
        if self.decTickSteps != "auto":
            ticsDict['major']['dec']=self.decTickSteps
        
        RALocs=[]
        decLocs=[]
        RALabels=[]
        decLabels=[]
        key="major"
        #for key in ticsDict.keys(): # key is major or minor
        if self.axesLabels == "sexagesimal":
            self.RAAxisLabel="R.A. ("+equinoxLabel+")"
            self.decAxisLabel="Dec. ("+equinoxLabel+")"
            RADegStep=ticsDict[key]['RA']['deg']
            decDegStep=ticsDict[key]['dec']['deg']
        elif self.axesLabels == "decimal":
            self.RAAxisLabel="R.A. Degrees ("+equinoxLabel+")"
            self.decAxisLabel="Dec. Degrees ("+equinoxLabel+")"
            RADegStep=ticsDict[key]['RA']
            decDegStep=ticsDict[key]['dec']
        else:
            raise Exception("axesLabels must be either 'sexagesimal' or 'decimal'")
        
        xArray=numpy.arange(0, self.data.shape[1], 1)
        yArray=numpy.arange(0, self.data.shape[0], 1)
        xWCS=self.wcs.pix2wcs(xArray, numpy.zeros(xArray.shape[0], dtype=float))
        yWCS=self.wcs.pix2wcs(numpy.zeros(yArray.shape[0], dtype=float), yArray)
        xWCS=numpy.array(xWCS)
        yWCS=numpy.array(yWCS)
        ras=xWCS[:,0]
        decs=yWCS[:,1]
        RAEdges=numpy.array([ras[0], ras[-1]])
        RAMin=RAEdges.min()
        RAMax=RAEdges.max()
        decMin=decs.min()
        decMax=decs.max()
        
        # Work out if wrapped around
        midRAPix, midDecPix=self.wcs.wcs2pix((RAEdges[1]+RAEdges[0])/2.0, (decMax+decMin)/2.0)
        if midRAPix < 0 or midRAPix > self.wcs.header['NAXIS1']:
            wrappedRA=True
        else:
            wrappedRA=False
            
        # Note RA, dec work in opposite sense below because E at left
        if ras[1] < ras[0]:
            self.flipXAxis=False
            ra2x=interpolate.interp1d(ras[::-1], xArray[::-1], kind='linear')
        else:
            self.flipXAxis=True
            ra2x=interpolate.interp1d(ras, xArray, kind='linear')
        if decs[1] < decs[0]:
            self.flipYAxis=True
            dec2y=interpolate.interp1d(decs[::-1], yArray[::-1], kind='linear')
        else:
            self.flipYAxis=False
            dec2y=interpolate.interp1d(decs, yArray, kind='linear')
        
        if wrappedRA == False:
            RAPlotMin=RADegStep*math.modf(RAMin/RADegStep)[1]
            RAPlotMax=RADegStep*math.modf(RAMax/RADegStep)[1]
            if RAPlotMin < RAMin:
                RAPlotMin=RAPlotMin+RADegStep
            if RAPlotMax >= RAMax:
                RAPlotMax=RAPlotMax-RADegStep
            RADegs=numpy.arange(RAPlotMin, RAPlotMax+0.0001, RADegStep)
        else:
            RAPlotMin=RADegStep*math.modf(RAMin/RADegStep)[1]
            RAPlotMax=RADegStep*math.modf(RAMax/RADegStep)[1]
            if RAPlotMin > RAMin:
                RAPlotMin=RAPlotMin-RADegStep
            if RAPlotMax <= RAMax:
                RAPlotMax=RAPlotMax+RADegStep
            for i in range(ras.shape[0]):
                if ras[i] >= RAMax and ras[i] <= 360.0:
                    ras[i]=ras[i]-360.0
            if ras[1] < ras[0]:
                ra2x=interpolate.interp1d(ras[::-1], xArray[::-1], kind='linear')
            else:
                ra2x=interpolate.interp1d(ras, xArray, kind='linear')
            RADegs=numpy.arange(RAPlotMin, RAPlotMax-360.0-0.0001, -RADegStep)

        decPlotMin=decDegStep*math.modf(decMin/decDegStep)[1]
        decPlotMax=decDegStep*math.modf(decMax/decDegStep)[1]
        if decPlotMin < decMin:
            decPlotMin=decPlotMin+decDegStep
        if decPlotMax >= decMax:
            decPlotMax=decPlotMax-decDegStep
        decDegs=numpy.arange(decPlotMin, decPlotMax+0.0001, decDegStep)
        
        if key == "major":
            if axesLabels == "sexagesimal":
                for r in RADegs:
                    if r < 0:
                        r=r+360.0
                    h, m, s=astCoords.decimal2hms(r, ":").split(":")
                    hInt=int(round(float(h)))
                    if ticsDict[key]['RA']['unit'] == 'h' and (60.0-float(m)) < 0.01: # Check for rounding error
                        hInt=hInt+1
                    if hInt < 10:
                        hString="0"+str(hInt)
                    else:
                        hString=str(hInt)
                    mInt=int(round(float(m)))
                    if ticsDict[key]['RA']['unit'] == 'm' and (60.0-float(s)) < 0.01: # Check for rounding error
                        mInt=mInt+1
                    if mInt < 10:
                        mString="0"+str(mInt)
                    else:
                        mString=str(mInt)
                    sInt=int(round(float(s)))
                    if sInt < 10:
                        sString="0"+str(sInt)
                    else:
                        sString=str(sInt)
                    if ticsDict[key]['RA']['unit'] == 'h':
                        rString=hString+"$^{\sf{h}}$"
                    elif ticsDict[key]['RA']['unit'] == 'm':
                        rString=hString+"$^{\sf{h}}$"+mString+"$^{\sf{m}}$"
                    else:
                        rString=hString+"$^{\sf{h}}$"+mString+"$^{\sf{m}}$"+sString+"$^{\sf{s}}$"
                    RALabels.append(rString)
                for D in decDegs:
                    d, m, s=astCoords.decimal2dms(D, ":").split(":")
                    dInt=int(round(float(d)))
                    if ticsDict[key]['dec']['unit'] == 'd' and (60.0-float(m)) < 0.01: # Check for rounding error
                        dInt=dInt+1
                    if dInt < 10 and dInt >= 0 and D > 0:
                        dString="+0"+str(dInt)
                    elif dInt > -10 and dInt <= 0 and D < 0:
                        dString="-0"+str(abs(dInt))
                    elif dInt >= 10:
                        dString="+"+str(dInt)
                    else:
                        dString=str(dInt)
                    mInt=int(round(float(m)))
                    if ticsDict[key]['dec']['unit'] == 'm' and (60.0-float(s)) < 0.01: # Check for rounding error
                        mInt=mInt+1
                    if mInt < 10:
                        mString="0"+str(mInt)
                    else:
                        mString=str(mInt)
                    sInt=int(round(float(s)))
                    if sInt < 10:
                        sString="0"+str(sInt)
                    else:
                        sString=str(sInt)
                    if ticsDict[key]['dec']['unit'] == 'd':
                        dString=dString+DEG
                    elif ticsDict[key]['dec']['unit'] == 'm':
                        dString=dString+DEG+mString+PRIME
                    else:
                        dString=dString+DEG+mString+PRIME+sString+DOUBLE_PRIME               
                    decLabels.append(dString)
            elif axesLabels == "decimal":
                                
                if wrappedRA == False:
                    RALabels=RALabels+RADegs.tolist()
                else:
                    nonNegativeLabels=[]
                    for r in RADegs:
                        if r < 0:
                            r=r+360.0
                        nonNegativeLabels.append(r)
                    RALabels=RALabels+nonNegativeLabels
                decLabels=decLabels+decDegs.tolist()
                
                # Format RALabels, decLabels to same number of d.p.
                dpNumRA=len(str(ticsDict['major']['RA']).split(".")[-1])
                dpNumDec=len(str(ticsDict['major']['dec']).split(".")[-1])
                for i in range(len(RALabels)):
                    fString="%."+str(dpNumRA)+"f"
                    RALabels[i]=fString % (RALabels[i])
                for i in range(len(decLabels)):
                    fString="%."+str(dpNumDec)+"f"
                    decLabels[i]=fString % (decLabels[i])                                
        
        if key == 'minor':
            RALabels=RALabels+RADegs.shape[0]*['']
            decLabels=decLabels+decDegs.shape[0]*['']
        
        RALocs=RALocs+ra2x(RADegs).tolist()
        decLocs=decLocs+dec2y(decDegs).tolist()
            
        self.ticsRA=[RALocs, RALabels]
        self.ticsDec=[decLocs, decLabels]
        

    def save(self, fileName):
        """Saves the ImagePlot in any format that matplotlib can understand, as determined from the 
        fileName extension.
        
        @type fileName: string
        @param fileName: path where plot will be written
        
        """
        
        pylab.draw()
        pylab.savefig(fileName)
        
        
    def getTickSteps(self):
        """Chooses the appropriate WCS coordinate tick steps for the plot based on its size.
        Whether the ticks are decimal or sexagesimal is set by self.axesLabels.
        
        Note: minor ticks not used at the moment.
        
        @rtype: dictionary
        @return: tick step sizes for major, minor plot ticks, in format {'major', 'minor'}
                
        """
        
        # Aim for 5 major tick marks on a plot
        xArray=numpy.arange(0, self.data.shape[1], 1)
        yArray=numpy.arange(0, self.data.shape[0], 1)
        xWCS=self.wcs.pix2wcs(xArray, numpy.zeros(xArray.shape[0], dtype=float))
        yWCS=self.wcs.pix2wcs(numpy.zeros(yArray.shape[0], dtype=float), yArray)
        xWCS=numpy.array(xWCS)
        yWCS=numpy.array(yWCS)
        ras=xWCS[:,0]
        decs=yWCS[:,1]
        RAEdges=numpy.array([ras[0], ras[-1]])
        RAMin=RAEdges.min()
        RAMax=RAEdges.max()
        decMin=decs.min()
        decMax=decs.max()
        
        # Work out if wrapped around
        midRAPix, midDecPix=self.wcs.wcs2pix((RAEdges[1]+RAEdges[0])/2.0, (decMax+decMin)/2.0)
        if midRAPix < 0 or midRAPix > self.wcs.header['NAXIS1']:
            wrappedRA=True
        else:
            wrappedRA=False
        if wrappedRA == False:
            RAWidthDeg=RAMax-RAMin
        else:
            RAWidthDeg=(360.0-RAMax)+RAMin
        decHeightDeg=decMax-decMin

        ticsDict={}
        ticsDict['major']={}
        ticsDict['minor']={}
        if self.axesLabels == "sexagesimal":
            
            matchIndex = 0
            for i in range(len(RA_TICK_STEPS)):
                if RAWidthDeg/2.5 > RA_TICK_STEPS[i]['deg']:
                    matchIndex = i
            
            ticsDict['major']['RA']=RA_TICK_STEPS[matchIndex]
            ticsDict['minor']['RA']=RA_TICK_STEPS[matchIndex-1]

            matchIndex = 0
            for i in range(len(DEC_TICK_STEPS)):
                if decHeightDeg/2.5 > DEC_TICK_STEPS[i]['deg']:
                    matchIndex = i
                                
            ticsDict['major']['dec']=DEC_TICK_STEPS[matchIndex]
            ticsDict['minor']['dec']=DEC_TICK_STEPS[matchIndex-1]
            
            return ticsDict
            
        elif self.axesLabels == "decimal":
            
            matchIndex = 0
            for i in range(len(DECIMAL_TICK_STEPS)):
                if RAWidthDeg/2.5 > DECIMAL_TICK_STEPS[i]:
                    matchIndex = i
            
            ticsDict['major']['RA']=DECIMAL_TICK_STEPS[matchIndex]
            ticsDict['minor']['RA']=DECIMAL_TICK_STEPS[matchIndex-1]
            
            matchIndex = 0
            for i in range(len(DECIMAL_TICK_STEPS)):
                if decHeightDeg/2.5 > DECIMAL_TICK_STEPS[i]:
                    matchIndex = i
                    
            ticsDict['major']['dec']=DECIMAL_TICK_STEPS[matchIndex]
            ticsDict['minor']['dec']=DECIMAL_TICK_STEPS[matchIndex-1]
            
            return ticsDict
        
        else:
            raise Exception("axesLabels must be either 'sexagesimal' or 'decimal'")