/usr/share/doc/libplplot12/examples/c/tutor.c is in libplplot-dev 5.10.0+dfsg2-0.1ubuntu2.
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//
// Tony Richardson
//
// This program is intended to be used as a template for creating simple
// two-dimensional plotting programs which use the PLplot plotting
// library. The program was written with an emphasis on trying to clearly
// illustrate how to use the PLplot library functions.
//
// This program reads data for M lines with N points each from an input
// data file and plots them on the same graph using different symbols. It
// draws axes with labels and places a title at the top of the figure. A
// legend is drawn to the right of the figure. The input data file must
// have the following format:
//
// M N
// x[1] y[1][1] y[1][2] . . . y[1][M]
// x[2] y[2][1] y[2][2] . . . y[2][M]
// x[3] y[3][1] y[3][2] . . . y[3][M]
// . . . . . . .
// . . . . . . .
// . . . . . . .
// x[N] y[N][1] y[N][2] . . . y[N][M]
//
// (The first line contains the integer values M and N. The succeeding
// N lines contain the x-coordinate and the corresponding y-coordinates
// of each of the M lines.)
//
#include "plcdemos.h"
static int
error( char *str );
//
// You can select a different set of symbols to use when plotting the
// lines by changing the value of OFFSET.
//
#define OFFSET 2
int
main( int argc, char *argv[] )
{
// ============== Begin variable definition section. =============
//
// i, j, and k are counting variables used in loops and such. M is the
// number of lines to be plotted and N is the number of sample points
// for each line.
//
int i, j, k, M, N, leglen;
//
// x is a pointer to an array containing the N x-coordinate values. y
// points to an array of M pointers each of which points to an array
// containing the N y-coordinate values for that line.
//
PLFLT *x, **y;
// Define storage for the min and max values of the data.
PLFLT xmin, xmax, ymin, ymax, xdiff, ydiff;
// Define storage for the filename and define the input file pointer.
char filename[80], string[80], tmpstr[80];
FILE *datafile;
// Here are the character strings that appear in the plot legend.
static char *legend[] =
{
"Aardvarks",
"Gnus",
"Llamas",
NULL
}; // Make sure last element is NULL
// ============== Read in data from input file. =============
// Parse and process command line arguments
(void) plparseopts( &argc, argv, PL_PARSE_FULL );
// First prompt the user for the input data file name
printf( "Enter input data file name. " );
scanf( "%s", filename );
// and open the file.
datafile = fopen( filename, "r" );
if ( datafile == NULL ) // error opening input file
error( "Error opening input file." );
// Read in values of M and N
k = fscanf( datafile, "%d %d", &M, &N );
if ( k != 2 ) // something's wrong
error( "Error while reading data file." );
// Allocate memory for all the arrays.
x = (PLFLT *) malloc( N * sizeof ( PLFLT ) );
if ( x == NULL )
error( "Out of memory!" );
y = (PLFLT **) malloc( M * sizeof ( PLFLT * ) );
if ( y == NULL )
error( "Out of memory!" );
for ( i = 0; i < M; i++ )
{
y[i] = (PLFLT *) malloc( N * sizeof ( PLFLT ) );
if ( y[i] == NULL )
error( "Out of memory!" );
}
// Now read in all the data.
for ( i = 0; i < N; i++ ) // N points
{
k = fscanf( datafile, "%f", &x[i] );
if ( k != 1 )
error( "Error while reading data file." );
for ( j = 0; j < M; j++ ) // M lines
{
k = fscanf( datafile, "%f", &y[j][i] );
if ( k != 1 )
error( "Error while reading data file." );
}
}
// ============== Graph the data. =============
// Set graph to portrait orientation. (Default is landscape.)
// (Portrait is usually desired for inclusion in TeX documents.)
plsori( 1 );
// Initialize plplot
plinit();
//
// We must call pladv() to advance to the first (and only) subpage.
// You might want to use plenv() instead of the pladv(), plvpor(),
// plwind() sequence.
//
pladv( 0 );
//
// Set up the viewport. This is the window into which the data is
// plotted. The size of the window can be set with a call to
// plvpor(), which sets the size in terms of normalized subpage
// coordinates. I want to plot the lines on the upper half of the
// page and I want to leave room to the right of the figure for
// labelling the lines. We must also leave room for the title and
// labels with plvpor(). Normally a call to plvsta() can be used
// instead.
//
plvpor( 0.15, 0.70, 0.5, 0.9 );
//
// We now need to define the size of the window in user coordinates.
// To do this, we first need to determine the range of the data
// values.
//
xmin = xmax = x[0];
ymin = ymax = y[0][0];
for ( i = 0; i < N; i++ )
{
if ( x[i] < xmin )
xmin = x[i];
if ( x[i] > xmax )
xmax = x[i];
for ( j = 0; j < M; j++ )
{
if ( y[j][i] < ymin )
ymin = y[j][i];
if ( y[j][i] > ymax )
ymax = y[j][i];
}
}
//
// Now set the size of the window. Leave a small border around the
// data.
//
xdiff = ( xmax - xmin ) / 20.;
ydiff = ( ymax - ymin ) / 20.;
plwind( xmin - xdiff, xmax + xdiff, ymin - ydiff, ymax + ydiff );
//
// Call plbox() to draw the axes (see the PLPLOT manual for
// information about the option strings.)
//
plbox( "bcnst", 0.0, 0, "bcnstv", 0.0, 0 );
//
// Label the axes and title the graph. The string "#gm" plots the
// Greek letter mu, all the Greek letters are available, see the
// PLplot manual.
//
pllab( "Time (weeks)", "Height (#gmparsecs)", "Specimen Growth Rate" );
//
// Plot the data. plpoin() draws a symbol at each point. plline()
// connects all the points.
//
for ( i = 0; i < M; i++ )
{
plpoin( N, x, y[i], i + OFFSET );
plline( N, x, y[i] );
}
//
// Draw legend to the right of the chart. Things get a little messy
// here. You may want to remove this section if you don't want a
// legend drawn. First find length of longest string.
//
leglen = 0;
for ( i = 0; i < M; i++ )
{
if ( legend[i] == NULL )
break;
j = strlen( legend[i] );
if ( j > leglen )
leglen = j;
}
//
// Now build the string. The string consists of an element from the
// legend string array, padded with spaces, followed by one of the
// symbols used in plpoin above.
//
for ( i = 0; i < M; i++ )
{
if ( legend[i] == NULL )
break;
strcpy( string, legend[i] );
j = strlen( string );
if ( j < leglen ) // pad string with spaces
{
for ( k = j; k < leglen; k++ )
string[k] = ' ';
string[k] = '\0';
}
// pad an extra space
strcat( string, " " );
j = strlen( string );
// insert the ASCII value of the symbol plotted with plpoin()
string[j] = i + OFFSET;
string[j + 1] = '\0';
// plot the string
plmtex( "rv", 1., 1. - (double) ( i + 1 ) / ( M + 1 ), 0., string );
}
// Tell plplot we are done with this page.
pladv( 0 ); // advance page
// Don't forget to call plend() to finish off!
plend();
exit( 0 );
}
static int
error( char *str )
{
fprintf( stderr, "%s\n", str );
exit( 1 );
}
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