Using open-source and free software for scientific plotting
Plotting is somewhat necessary to convey scientific discovery to external audience. Python is a great tool for that end, but the script for plotting usually requires multiple lines. Other than Python, Xmgrace and gnuplot are good tools, and maybe more handy to visualize data in a few lines of codes. Most importantly, both of them have a bunch of mathematical libraries for data processing, such as curve fitting.
Xmgrace
To make a plot of a data file (named file.dat), one line is enough to get the plot:
xmgrace file.dat
If there are multi-columns in the file, and one wants to plot e.g., 1st column and 3rd column, then use:
xmgrace -block file.dat -bxy 1:3
If one wants to plot all other than the first column against the first column (x-axis), then use:
xmgrace -nxy file.dat
Executing the command, a user-friendly GUI shows up. One can do mathematical operations on the data set and/or change lines/width/fonts. Note that Xmgrace is for 2D plot only.
gnuplot
gnuplot works in an interactive way. One can use the following command to call it:
gnuplot
Once in the command line of gnuplot, one can make a plot of data in a file by:
gnuplot> plot 'file.dat'
gnuplot> plot 'file.dat' using 1:3
gnuplot> plot for [i=2:*] 'file.dat' using 1:i