This recipe will introduce gnuplot's ability to place objects at locations specified in a datafile or by mathematical functions, and to define their properties dynamically to convey information about the data. The following figure shows how gnuplot plots circles:
We have provided a datafile called
parabolaCircles.text, which is similar to the
parabola.text file that we created previously with gnuplot's help, but with a third column that consists of some random numbers. Make sure this file is in your current directory so that gnuplot can find it. Alternatively, use any datafile you like with three columns.