Functions
gnuplot_i.c File Reference

C interface to gnuplot. More...

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Functions

char const * gnuplot_tmpfile (gnuplot_ctrl *handle)
void gnuplot_plot_atmpfile (gnuplot_ctrl *handle, char const *tmp_filename, char const *title)
gnuplot_ctrlgnuplot_init (void)
 Opens up a gnuplot session, ready to receive commands.
void gnuplot_close (gnuplot_ctrl *handle)
 Closes a gnuplot session previously opened by gnuplot_init()
void gnuplot_cmd (gnuplot_ctrl *handle, char const *cmd,...)
 Sends a command to an active gnuplot session.
void gnuplot_setstyle (gnuplot_ctrl *h, char *plot_style)
 Change the plotting style of a gnuplot session.
void gnuplot_set_xlabel (gnuplot_ctrl *h, char *label)
 Sets the x label of a gnuplot session.
void gnuplot_set_ylabel (gnuplot_ctrl *h, char *label)
 Sets the y label of a gnuplot session.
void gnuplot_resetplot (gnuplot_ctrl *h)
 Resets a gnuplot session (next plot will erase previous ones).
void gnuplot_plot_x (gnuplot_ctrl *handle, double *d, int n, char *title)
 Plots a 2d graph from a list of doubles.
void gnuplot_plot_xy (gnuplot_ctrl *handle, double *x, double *y, int n, char *title)
 Plot a 2d graph from a list of points.
void gnuplot_plot_once (char *title, char *style, char *label_x, char *label_y, double *x, double *y, int n)
 Open a new session, plot a signal, close the session.
void gnuplot_plot_slope (gnuplot_ctrl *handle, double a, double b, char *title)
 Plot a slope on a gnuplot session.
void gnuplot_plot_equation (gnuplot_ctrl *h, char *equation, char *title)
 Plot a curve of given equation y=f(x).
int gnuplot_write_x_csv (char const *fileName, double const *d, int n, char const *title)
int gnuplot_write_xy_csv (char const *fileName, double const *x, double const *y, int n, char const *title)
int gnuplot_write_multi_csv (char const *fileName, double const **xListPtr, int n, int numColumns, char const *title)

Detailed Description

C interface to gnuplot.

Author:
N. Devillard
Date:
Sep 1998
Version:
Revision:
2.10

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.

Definition in file gnuplot_i.c.


Function Documentation

void gnuplot_close ( gnuplot_ctrl handle)

Closes a gnuplot session previously opened by gnuplot_init()

Parameters:
handleGnuplot session control handle.
Returns:
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.

Definition at line 137 of file gnuplot_i.c.

void gnuplot_cmd ( gnuplot_ctrl handle,
char const *  cmd,
  ... 
)

Sends a command to an active gnuplot session.

Parameters:
handleGnuplot session control handle
cmdCommand 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:

  gnuplot_cmd(g, "plot %d*x", 23.0);
  gnuplot_cmd(g, "plot %.18e * cos(%.18e * x)", 32.0, -3.0);

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.

Definition at line 183 of file gnuplot_i.c.

gnuplot_ctrl* gnuplot_init ( void  )

Opens up a gnuplot session, ready to receive commands.

Returns:
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().

Definition at line 89 of file gnuplot_i.c.

void gnuplot_plot_atmpfile ( gnuplot_ctrl handle,
char const *  tmp_filename,
char const *  title 
)

Plot a temporary file.

Author:
Peter (12/9/2011)
Parameters:
handle
tmp_filename
title

Definition at line 705 of file gnuplot_i.c.

void gnuplot_plot_equation ( gnuplot_ctrl h,
char *  equation,
char *  title 
)

Plot a curve of given equation y=f(x).

Parameters:
hGnuplot session control handle.
equationEquation to plot.
titleTitle of the plot.
Returns:
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:

        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) ;

Definition at line 512 of file gnuplot_i.c.

void gnuplot_plot_once ( char *  title,
char *  style,
char *  label_x,
char *  label_y,
double *  x,
double *  y,
int  n 
)

Open a new session, plot a signal, close the session.

Parameters:
titlePlot title
stylePlot style
label_xLabel for X
label_yLabel for Y
xArray of X coordinates
yArray of Y coordinates (can be NULL)
nNumber of values in x and y.
Returns:

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.

Definition at line 453 of file gnuplot_i.c.

void gnuplot_plot_slope ( gnuplot_ctrl handle,
double  a,
double  b,
char *  title 
)

Plot a slope on a gnuplot session.

Parameters:
handleGnuplot session control handle.
aSlope.
bIntercept.
titleTitle of the plot.
Returns:
void

Plot a slope on a gnuplot session. The provided slope has an equation of the form y=ax+b

Example:

    gnuplot_ctrl    *   h ;
    double              a, b ;

    h = gnuplot_init() ;
    gnuplot_plot_slope(h, 1.0, 0.0, "unity slope") ;
    sleep(2) ;
    gnuplot_close(h) ;

Definition at line 494 of file gnuplot_i.c.

void gnuplot_plot_x ( gnuplot_ctrl handle,
double *  d,
int  n,
char *  title 
)

Plots a 2d graph from a list of doubles.

Parameters:
handleGnuplot session control handle.
dArray of doubles.
nNumber of values in the passed array.
titleTitle of the plot.
Returns:
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:

    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) ;

Definition at line 331 of file gnuplot_i.c.

void gnuplot_plot_xy ( gnuplot_ctrl handle,
double *  x,
double *  y,
int  n,
char *  title 
)

Plot a 2d graph from a list of points.

Parameters:
handleGnuplot session control handle.
xPointer to a list of x coordinates.
yPointer to a list of y coordinates.
nNumber of doubles in x (assumed the same as in y).
titleTitle of the plot.
Returns:
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.

    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) ;

Definition at line 397 of file gnuplot_i.c.

void gnuplot_resetplot ( gnuplot_ctrl h)

Resets a gnuplot session (next plot will erase previous ones).

Parameters:
hGnuplot session control handle.
Returns:
void

Resets a gnuplot session, i.e. the next plot will erase all previous ones.

Definition at line 284 of file gnuplot_i.c.

void gnuplot_set_xlabel ( gnuplot_ctrl h,
char *  label 
)

Sets the x label of a gnuplot session.

Parameters:
hGnuplot session control handle.
labelCharacter string to use for X label.
Returns:
void

Sets the x label for a gnuplot session.

Definition at line 250 of file gnuplot_i.c.

void gnuplot_set_ylabel ( gnuplot_ctrl h,
char *  label 
)

Sets the y label of a gnuplot session.

Parameters:
hGnuplot session control handle.
labelCharacter string to use for Y label.
Returns:
void

Sets the y label for a gnuplot session.

Definition at line 267 of file gnuplot_i.c.

void gnuplot_setstyle ( gnuplot_ctrl h,
char *  plot_style 
)

Change the plotting style of a gnuplot session.

Parameters:
hGnuplot session control handle
plot_stylePlotting-style to use (character string)
Returns:
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

Definition at line 219 of file gnuplot_i.c.

char const * gnuplot_tmpfile ( gnuplot_ctrl handle)

Creates a temporary file name for writing

Author:
Peter (12/9/2011)
Parameters:
handle
Returns:
char const * Pointer to file name string.

Definition at line 658 of file gnuplot_i.c.

int gnuplot_write_multi_csv ( char const *  fileName,
double const **  xListPtr,
int  n,
int  numColumns,
char const *  title 
)

Writes a multi column CSV file for use with gnuplot commands later. Allows files to also be saved for post analysis with excel for example. Note that when used with gnuplot, since there may be more than one column the whole "1:3" or whatever should be used.

Uses title as gnuplot "comment" on the first line.

Author:
Peter H Maresh 11/8/2011
Parameters:
fileNamefile name to write to. This should be the same name used in the gnuplot command
xListPtrA list of pointers to column buffers
n
numColumnsLength of xListPtr list. Note that the CSV file will add an additional "index" column first.
titleTitle to write for the first line of the .csv file, will be preceeded by "#"
Returns:
int <0 if file wasn't written.

Definition at line 605 of file gnuplot_i.c.

int gnuplot_write_x_csv ( char const *  fileName,
double const *  d,
int  n,
char const *  title 
)

Writes a CSV file for use with gnuplot commands later. Allows files to also be saved for post analysis with excel for example. Arguments are similar to gnuplot_plot_x()

Uses title as gnuplot "comment" on the first line.

Author:
Peter H Maresh 11/8/2011
Parameters:
fileNamefile name to write to. This should be the same name used in the gnuplot command
d
n
title
Returns:
int <0 if error writing file.

Definition at line 528 of file gnuplot_i.c.

int gnuplot_write_xy_csv ( char const *  fileName,
double const *  x,
double const *  y,
int  n,
char const *  title 
)

Writes a CSV file for use with gnuplot commands later. Allows files to also be saved for post analysis with excel for example. Arguments are similar to gnuplot_plot_xy()

Uses title as gnuplot "comment" on the first line.

Author:
Peter H Maresh 11/8/2011
Parameters:
fileNamefile name to write to. This should be the same name used in the gnuplot command
x
y
n
title
Returns:
int <0 if file wasn't written.

Definition at line 566 of file gnuplot_i.c.


Last modified: Sun Apr 8 2012 17:28:19