- GnuPlot is a commonly used program to make graphs
- It can produce its output to different devices:
- terminal (default)
- output file
- It can produce its output to many different format, including:
- X11
- postscript format
- gif format
- By default, the plots are displayed to the standard output.
- The set output
command redirects the display to the specified file or device.
- Example:
set output "filename" This command will re-direct the output to file "filename"
set output This command will reset the output to STDOUT (terminal)
- When gnuplot starts, it will use the format
associated with the "terminal"
In our X-window UNIX workstation, this format is X11
- The
set terminal TERMINAL-TYPE [parameters]
command can change the output format.
- Here are some useful format that you can use:
set terminal // Give a list of supported format set terminal postscript portrait color // Postscript color (good for figures in research paper) set terminal gif size 800,600 // Postscript color (good for figures in research paper)
- Warning:
- Once you changed the
output format, it's hard to get back the original (default) format
- If you want to go back to the
original output format,
you should save it using this command:
set terminal push (save current output format)
- You can go back to the
saved setting
using the command:
set terminal pop (restore the saved output format)
- Once you changed the
output format, it's hard to get back the original (default) format
- The most common data format in input files is:
- Column 1 contains time values
- Column 2 contains performance data from source 1
- Column 3 contains performance data from source 2
- And so on...
- NOTE: most input files only have 2 columns.
column 1 column 2 column 3 .... ------------------------------------------------ 0 4 5 ... 0.1 4.4 5.3 ... 0.2 4.6 5.8 ... 0.3 4.7 5.9 ... 0.4 4.3 6.3 ... .......
- The following command will create a graph (plot) using
data from a file "input1" where:
- Data points from column 1 as X-values
- Data points from column 2 as Y-values
- Data from other columns are ignored
- The legend for the plot is titled "Plot 1"
- The color used is "1" (red)
plot "input1" using 1:2 title "Plot 1" with lines 1
- The following command will create a graph (plot) using
data from a file "input1" where:
- Data points from column 1 as X-values
- Data points from column 3 as Y-values
- Data from other columns are ignored
- The legend for the plot is titled "Plot 2"
- The color used is "2" (green)
plot "input1" using 1:3 title "Plot 2" with lines 2
- The following command will create
two plots
in one single graph where:
- Data points from column 1 from "input1" as X-values
- Data points from column 2 as Y-values
- The legend for this plot is titled "Plot 1"
- The color used is "1" (red)
- Data points from column 1 from "input1" as X-values
- Data points from column 3 as Y-values
- The legend for this plot is titled "Plot 2"
- The color used is "3" (blue)
plot "input1" using 1:2 title "Plot 1" with lines 1, \ "input1" using 1:3 title "Plot 2" with lines 3
- The replot
command will repeat the
last plot command
that gnuplot has executed.
The replot command is useful after you have changed to OUTPUT device (and possibly the output format also).
Example: suppose you have plotted a graph and now you want the plot as a "gif" file, then do:
set terminal push (save original format setting) set terminal gif size 640,480 (change to new format) set output "out.gif" (set file name for output) replot (save gif plot in file) set terminal pop (restore original format setting)
- Try the above commands using this sample input data file.
- Sample Input data file "input1":
(Demo above code)
- Prog file: click here