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gnuplot_i.c
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721 lines (598 loc) · 19.1 KB
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/*-------------------------------------------------------------------------*/
/**
@file gnuplot_i.c
@author N. Devillard
@date Sep 1998
@version $Revision: 2.10 $
@brief C interface to gnuplot.
gnuplot is a freely available, command-driven graphical display tool for
Unix. It compiles and works quite well on a number of Unix flavours as
well as other operating systems. The following module enables sending
display requests to gnuplot through simple C calls.
*/
/*--------------------------------------------------------------------------*/
/*
$Id: gnuplot_i.c,v 2.10 2003/01/27 08:58:04 ndevilla Exp $
$Author: ndevilla $
$Date: 2003/01/27 08:58:04 $
$Revision: 2.10 $
*/
/*---------------------------------------------------------------------------
Includes
---------------------------------------------------------------------------*/
#include "gnuplot_i.h"
/*---------------------------------------------------------------------------
Defines
---------------------------------------------------------------------------*/
/** Maximal size of a gnuplot command */
#define GP_CMD_SIZE 2048
/** Maximal size of a plot title */
#define GP_TITLE_SIZE 80
/** Maximal size for an equation */
#define GP_EQ_SIZE 512
/** Maximal size of a name in the PATH */
#define PATH_MAXNAMESZ 4096
/** Define P_tmpdir if not defined (this is normally a POSIX symbol) */
#ifndef P_tmpdir
#define P_tmpdir "."
#endif
/*---------------------------------------------------------------------------
Function codes
---------------------------------------------------------------------------*/
/*-------------------------------------------------------------------------*/
/**
@brief Find out where a command lives in your PATH.
@param pname Name of the program to look for.
@return pointer to statically allocated character string.
This is the C equivalent to the 'which' command in Unix. It parses
out your PATH environment variable to find out where a command
lives. The returned character string is statically allocated within
this function, i.e. there is no need to free it. Beware that the
contents of this string will change from one call to the next,
though (as all static variables in a function).
The input character string must be the name of a command without
prefixing path of any kind, i.e. only the command name. The returned
string is the path in which a command matching the same name was
found.
Examples (assuming there is a prog named 'hello' in the cwd):
@verbatim
gnuplot_get_program_path("hello") returns "."
gnuplot_get_program_path("ls") returns "/bin"
gnuplot_get_program_path("csh") returns "/usr/bin"
gnuplot_get_program_path("/bin/ls") returns NULL
@endverbatim
*/
/*-------------------------------------------------------------------------*/
char * gnuplot_get_program_path(char * pname)
{
int i, j, lg;
char * path;
static char buf[PATH_MAXNAMESZ];
/* Trivial case: try in CWD */
sprintf(buf, "./%s", pname) ;
if (access(buf, X_OK)==0) {
sprintf(buf, ".");
return buf ;
}
/* Try out in all paths given in the PATH variable */
buf[0] = 0;
path = getenv("PATH") ;
if (path!=NULL) {
for (i=0; path[i]; ) {
for (j=i ; (path[j]) && (path[j]!=':') ; j++);
lg = j - i;
strncpy(buf, path + i, lg);
if (lg == 0) buf[lg++] = '.';
buf[lg++] = '/';
strcpy(buf + lg, pname);
if (access(buf, X_OK) == 0) {
/* Found it! */
break ;
}
buf[0] = 0;
i = j;
if (path[i] == ':') i++ ;
}
} else {
fprintf(stderr, "PATH variable not set\n");
}
/* If the buffer is still empty, the command was not found */
if (buf[0] == 0) return NULL ;
/* Otherwise truncate the command name to yield path only */
lg = strlen(buf) - 1 ;
while (buf[lg]!='/') {
buf[lg]=0 ;
lg -- ;
}
buf[lg] = 0;
return buf ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Opens up a gnuplot session, ready to receive commands.
@return Newly allocated gnuplot control structure.
This opens up a new gnuplot session, ready for input. The struct
controlling a gnuplot session should remain opaque and only be
accessed through the provided functions.
The session must be closed using gnuplot_close().
*/
/*--------------------------------------------------------------------------*/
gnuplot_ctrl * gnuplot_init(void)
{
gnuplot_ctrl * handle ;
if (getenv("DISPLAY") == NULL) {
fprintf(stderr, "cannot find DISPLAY variable: is it set?\n") ;
}
if (gnuplot_get_program_path("gnuplot")==NULL) {
fprintf(stderr, "cannot find gnuplot in your PATH");
return NULL ;
}
/*
* Structure initialization:
*/
handle = (gnuplot_ctrl*)malloc(sizeof(gnuplot_ctrl)) ;
handle->nplots = 0 ;
gnuplot_setstyle(handle, "points") ;
handle->ntmp = 0 ;
handle->gnucmd = popen("gnuplot", "w") ;
if (handle->gnucmd == NULL) {
fprintf(stderr, "error starting gnuplot\n") ;
free(handle) ;
return NULL ;
}
return handle;
}
/*-------------------------------------------------------------------------*/
/**
@brief Closes a gnuplot session previously opened by gnuplot_init()
@param handle Gnuplot session control handle.
@return void
Kills the child PID and deletes all opened temporary files.
It is mandatory to call this function to close the handle, otherwise
temporary files are not cleaned and child process might survive.
*/
/*--------------------------------------------------------------------------*/
void gnuplot_close(gnuplot_ctrl * handle)
{
int i ;
if (pclose(handle->gnucmd) == -1) {
fprintf(stderr, "problem closing communication to gnuplot\n") ;
return ;
}
if (handle->ntmp) {
for (i=0 ; i<handle->ntmp ; i++) {
remove(handle->to_delete[i]) ;
}
}
free(handle) ;
return ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Sends a command to an active gnuplot session.
@param handle Gnuplot session control handle
@param cmd Command to send, same as a printf statement.
This sends a string to an active gnuplot session, to be executed.
There is strictly no way to know if the command has been
successfully executed or not.
The command syntax is the same as printf.
Examples:
@code
gnuplot_cmd(g, "plot %d*x", 23.0);
gnuplot_cmd(g, "plot %g * cos(%g * x)", 32.0, -3.0);
@endcode
Since the communication to the gnuplot process is run through
a standard Unix pipe, it is only unidirectional. This means that
it is not possible for this interface to query an error status
back from gnuplot.
*/
/*--------------------------------------------------------------------------*/
void gnuplot_cmd(gnuplot_ctrl * handle, char * cmd, ...)
{
va_list ap ;
char local_cmd[GP_CMD_SIZE];
va_start(ap, cmd);
vsprintf(local_cmd, cmd, ap);
va_end(ap);
strcat(local_cmd, "\n");
fputs(local_cmd, handle->gnucmd) ;
fflush(handle->gnucmd) ;
return ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Change the plotting style of a gnuplot session.
@param h Gnuplot session control handle
@param plot_style Plotting-style to use (character string)
@return void
The provided plotting style is a character string. It must be one of
the following:
- lines
- points
- linespoints
- impulses
- dots
- steps
- errorbars
- boxes
- boxeserrorbars
*/
/*--------------------------------------------------------------------------*/
void gnuplot_setstyle(gnuplot_ctrl * h, char * plot_style)
{
if (strcmp(plot_style, "lines") &&
strcmp(plot_style, "points") &&
strcmp(plot_style, "linespoints") &&
strcmp(plot_style, "impulses") &&
strcmp(plot_style, "dots") &&
strcmp(plot_style, "steps") &&
strcmp(plot_style, "errorbars") &&
strcmp(plot_style, "boxes") &&
strcmp(plot_style, "boxerrorbars")) {
fprintf(stderr, "warning: unknown requested style: using points\n") ;
strcpy(h->pstyle, "points") ;
} else {
strcpy(h->pstyle, plot_style) ;
}
return ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Sets the x label of a gnuplot session.
@param h Gnuplot session control handle.
@param label Character string to use for X label.
@return void
Sets the x label for a gnuplot session.
*/
/*--------------------------------------------------------------------------*/
void gnuplot_set_xlabel(gnuplot_ctrl * h, char * label)
{
char cmd[GP_CMD_SIZE] ;
sprintf(cmd, "set xlabel \"%s\"", label) ;
gnuplot_cmd(h, cmd) ;
return ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Sets the y label of a gnuplot session.
@param h Gnuplot session control handle.
@param label Character string to use for Y label.
@return void
Sets the y label for a gnuplot session.
*/
/*--------------------------------------------------------------------------*/
void gnuplot_set_ylabel(gnuplot_ctrl * h, char * label)
{
char cmd[GP_CMD_SIZE] ;
sprintf(cmd, "set ylabel \"%s\"", label) ;
gnuplot_cmd(h, cmd) ;
return ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Resets a gnuplot session (next plot will erase previous ones).
@param h Gnuplot session control handle.
@return void
Resets a gnuplot session, i.e. the next plot will erase all previous
ones.
*/
/*--------------------------------------------------------------------------*/
void gnuplot_resetplot(gnuplot_ctrl * h)
{
int i ;
if (h->ntmp) {
for (i=0 ; i<h->ntmp ; i++) {
remove(h->to_delete[i]) ;
}
}
h->ntmp = 0 ;
h->nplots = 0 ;
return ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Plots a 2d graph from a list of doubles.
@param handle Gnuplot session control handle.
@param d Array of doubles.
@param n Number of values in the passed array.
@param title Title of the plot.
@return void
Plots out a 2d graph from a list of doubles. The x-coordinate is the
index of the double in the list, the y coordinate is the double in
the list.
Example:
@code
gnuplot_ctrl *h ;
double d[50] ;
int i ;
h = gnuplot_init() ;
for (i=0 ; i<50 ; i++) {
d[i] = (double)(i*i) ;
}
gnuplot_plot_x(h, d, 50, "parabola") ;
sleep(2) ;
gnuplot_close(h) ;
@endcode
*/
/*--------------------------------------------------------------------------*/
void gnuplot_plot_x(
gnuplot_ctrl * handle,
double * d,
int n,
char * title
)
{
int i ;
int tmpfd ;
char name[128] ;
char cmd[GP_CMD_SIZE] ;
char line[GP_CMD_SIZE] ;
if (handle==NULL || d==NULL || (n<1)) return ;
/* Open one more temporary file? */
if (handle->ntmp == GP_MAX_TMP_FILES - 1) {
fprintf(stderr,
"maximum # of temporary files reached (%d): cannot open more",
GP_MAX_TMP_FILES) ;
return ;
}
/* Open temporary file for output */
sprintf(name, "%s/gnuplot-i-XXXXXX", P_tmpdir);
if ((tmpfd=mkstemp(name))==-1) {
fprintf(stderr,"cannot create temporary file: exiting plot") ;
return ;
}
/* Store file name in array for future deletion */
strcpy(handle->to_delete[handle->ntmp], name) ;
handle->ntmp ++ ;
/* Write data to this file */
for (i=0 ; i<n ; i++) {
sprintf(line, "%g\n", d[i]);
write(tmpfd, line, strlen(line));
}
close(tmpfd) ;
/* Command to be sent to gnuplot */
if (handle->nplots > 0) {
strcpy(cmd, "replot") ;
} else {
strcpy(cmd, "plot") ;
}
if (title == NULL) {
sprintf(line, "%s \"%s\" with %s", cmd, name, handle->pstyle) ;
} else {
sprintf(line, "%s \"%s\" title \"%s\" with %s", cmd, name,
title, handle->pstyle) ;
}
/* send command to gnuplot */
gnuplot_cmd(handle, line) ;
handle->nplots++ ;
return ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Plot a 2d graph from a list of points.
@param handle Gnuplot session control handle.
@param x Pointer to a list of x coordinates.
@param y Pointer to a list of y coordinates.
@param n Number of doubles in x (assumed the same as in y).
@param title Title of the plot.
@return void
Plots out a 2d graph from a list of points. Provide points through a list
of x and a list of y coordinates. Both provided arrays are assumed to
contain the same number of values.
@code
gnuplot_ctrl *h ;
double x[50] ;
double y[50] ;
int i ;
h = gnuplot_init() ;
for (i=0 ; i<50 ; i++) {
x[i] = (double)(i)/10.0 ;
y[i] = x[i] * x[i] ;
}
gnuplot_plot_xy(h, x, y, 50, "parabola") ;
sleep(2) ;
gnuplot_close(h) ;
@endcode
*/
/*--------------------------------------------------------------------------*/
void gnuplot_plot_xy(
gnuplot_ctrl * handle,
double * x,
double * y,
int n,
char * title
)
{
int i ;
int tmpfd ;
char name[128] ;
char cmd[GP_CMD_SIZE] ;
char line[GP_CMD_SIZE] ;
if (handle==NULL || x==NULL || y==NULL || (n<1)) return ;
/* Open one more temporary file? */
if (handle->ntmp == GP_MAX_TMP_FILES - 1) {
fprintf(stderr,
"maximum # of temporary files reached (%d): cannot open more",
GP_MAX_TMP_FILES) ;
return ;
}
/* Open temporary file for output */
sprintf(name, "%s/gnuplot-i-XXXXXX", P_tmpdir);
if ((tmpfd=mkstemp(name))==-1) {
fprintf(stderr,"cannot create temporary file: exiting plot") ;
return ;
}
/* Store file name in array for future deletion */
strcpy(handle->to_delete[handle->ntmp], name) ;
handle->ntmp ++ ;
/* Write data to this file */
for (i=0 ; i<n; i++) {
sprintf(line, "%g %g\n", x[i], y[i]) ;
write(tmpfd, line, strlen(line));
}
close(tmpfd) ;
/* Command to be sent to gnuplot */
if (handle->nplots > 0) {
strcpy(cmd, "replot") ;
} else {
strcpy(cmd, "plot") ;
}
if (title == NULL) {
sprintf(line, "%s \"%s\" with %s", cmd, name, handle->pstyle) ;
} else {
sprintf(line, "%s \"%s\" title \"%s\" with %s", cmd, name,
title, handle->pstyle) ;
}
/* send command to gnuplot */
gnuplot_cmd(handle, line) ;
handle->nplots++ ;
return ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Open a new session, plot a signal, close the session.
@param title Plot title
@param style Plot style
@param label_x Label for X
@param label_y Label for Y
@param x Array of X coordinates
@param y Array of Y coordinates (can be NULL)
@param n Number of values in x and y.
@return
This function opens a new gnuplot session, plots the provided
signal as an X or XY signal depending on a provided y, waits for
a carriage return on stdin and closes the session.
It is Ok to provide an empty title, empty style, or empty labels for
X and Y. Defaults are provided in this case.
*/
/*--------------------------------------------------------------------------*/
void gnuplot_plot_once(
char * title,
char * style,
char * label_x,
char * label_y,
double * x,
double * y,
int n
)
{
gnuplot_ctrl * handle ;
if (x==NULL || n<1) return ;
if ((handle = gnuplot_init()) == NULL) return ;
if (style!=NULL) {
gnuplot_setstyle(handle, style);
} else {
gnuplot_setstyle(handle, "lines");
}
if (label_x!=NULL) {
gnuplot_set_xlabel(handle, label_x);
} else {
gnuplot_set_xlabel(handle, "X");
}
if (label_y!=NULL) {
gnuplot_set_ylabel(handle, label_y);
} else {
gnuplot_set_ylabel(handle, "Y");
}
if (y==NULL) {
gnuplot_plot_x(handle, x, n, title);
} else {
gnuplot_plot_xy(handle, x, y, n, title);
}
printf("press ENTER to continue\n");
while (getchar()!='\n') {}
gnuplot_close(handle);
return ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Plot a slope on a gnuplot session.
@param handle Gnuplot session control handle.
@param a Slope.
@param b Intercept.
@param title Title of the plot.
@return void
Plot a slope on a gnuplot session. The provided slope has an
equation of the form y=ax+b
Example:
@code
gnuplot_ctrl * h ;
double a, b ;
h = gnuplot_init() ;
gnuplot_plot_slope(h, 1.0, 0.0, "unity slope") ;
sleep(2) ;
gnuplot_close(h) ;
@endcode
*/
/*--------------------------------------------------------------------------*/
void gnuplot_plot_slope(
gnuplot_ctrl * handle,
double a,
double b,
char * title
)
{
char stitle[GP_TITLE_SIZE] ;
char cmd[GP_CMD_SIZE] ;
if (title == NULL) {
strcpy(stitle, "no title") ;
} else {
strcpy(stitle, title) ;
}
if (handle->nplots > 0) {
sprintf(cmd, "replot %g * x + %g title \"%s\" with %s",
a, b, title, handle->pstyle) ;
} else {
sprintf(cmd, "plot %g * x + %g title \"%s\" with %s",
a, b, title, handle->pstyle) ;
}
gnuplot_cmd(handle, cmd) ;
handle->nplots++ ;
return ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Plot a curve of given equation y=f(x).
@param h Gnuplot session control handle.
@param equation Equation to plot.
@param title Title of the plot.
@return void
Plots out a curve of given equation. The general form of the
equation is y=f(x), you only provide the f(x) side of the equation.
Example:
@code
gnuplot_ctrl *h ;
char eq[80] ;
h = gnuplot_init() ;
strcpy(eq, "sin(x) * cos(2*x)") ;
gnuplot_plot_equation(h, eq, "sine wave", normal) ;
gnuplot_close(h) ;
@endcode
*/
/*--------------------------------------------------------------------------*/
void gnuplot_plot_equation(
gnuplot_ctrl * h,
char * equation,
char * title
)
{
char cmd[GP_CMD_SIZE];
char plot_str[GP_EQ_SIZE] ;
char title_str[GP_TITLE_SIZE] ;
if (title == NULL) {
strcpy(title_str, "no title") ;
} else {
strcpy(title_str, title) ;
}
if (h->nplots > 0) {
strcpy(plot_str, "replot") ;
} else {
strcpy(plot_str, "plot") ;
}
sprintf(cmd, "%s %s title \"%s\" with %s",
plot_str, equation, title_str, h->pstyle) ;
gnuplot_cmd(h, cmd) ;
h->nplots++ ;
return ;
}
/* vim: set ts=4 et sw=4 tw=75 */