C interface to gnuplot. More...

Data Structures
struct	_GNUPLOT_CTRL_
Typedefs
typedef struct _GNUPLOT_CTRL_	gnuplot_ctrl
	gnuplot session handle (opaque type).
Functions
gnuplot_ctrl *	gnuplot_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:: 1.11

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.h.

Typedef Documentation

gnuplot_ctrl

gnuplot session handle (opaque type).

This structure holds all necessary information to talk to a gnuplot session. It is built and returned by gnuplot_init() and later used by all functions in this module to communicate with the session, then meant to be closed by gnuplot_close().

This structure is meant to remain opaque, you normally do not need to know what is contained in there.

Function Documentation

void gnuplot_close ( gnuplot_ctrl * handle )

Closes a gnuplot session previously opened by gnuplot_init()

Parameters:

handle Gnuplot 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:

handle	Gnuplot session control handle
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:

  gnuplot_cmd(g, "plot %d*x", 23.0);
  gnuplot_cmd(g, "plot %g * cos(%g * 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.

Parameters:

handle	Gnuplot session control handle
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:

  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_equation	(	gnuplot_ctrl *	h,
		char *	equation,
		char *	title
	)

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

Parameters:

h	Gnuplot session control handle.
equation	Equation to plot.
title	Title 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:

title	Plot title
style	Plot style
label_x	Label for X
label_y	Label for Y
x	Array of X coordinates
y	Array of Y coordinates (can be NULL)
n	Number 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:

handle	Gnuplot session control handle.
a	Slope.
b	Intercept.
title	Title 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:

handle	Gnuplot session control handle.
d	Array of doubles.
n	Number of values in the passed array.
title	Title 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:

handle	Gnuplot session control handle.
x	Pointer to a list of x coordinates.
y	Pointer to a list of y coordinates.
n	Number of doubles in x (assumed the same as in y).
title	Title 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:

h	Gnuplot 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:

h	Gnuplot session control handle.
label	Character 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:

h	Gnuplot session control handle.
label	Character 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:

h	Gnuplot session control handle
plot_style	Plotting-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.

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:

fileName	file name to write to. This should be the same name used in the gnuplot command
xListPtr	A list of pointers to column buffers
n
numColumns	Length of xListPtr list. Note that the CSV file will add an additional "index" column first.
title	Title 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:

fileName	file 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:

fileName	file 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.

Data Structures

Typedefs

Functions

Detailed Description

Typedef Documentation

Function Documentation