how to overlay 2 graphs in a single plot in GNUplot

Question

I have two files that has the time as x axis and a value. I need to overlay these two on a single plot. Currently i tried it using GNUplot, but struck in the middle. Here is a sample file

01:03:05    6

01:03:15    6

and another file

01:03:55    6

01:04:10    6

I need to plot these two files (say x mark and some other symbol for differentiation) in a single plot. I dont know if it is possible to do that in GNUplot. Currently I have created two grids for each file. But I need both in a single plot. Here is what I have written

set multiplot layout 1,2    # engage multiplot mode

set xdata time          ## these three lines control how gnuplot

set timefmt '%H:%M:%S'  ## reads and writes time-formatted data.

set format x '%H:%M:%S' ##

set xtics 05           # make time spacing of 2 minutes

plot 'AAA' u 1:2      # plot the first data set 

plot 'BBB' u 1:2      # plot the second data set 

unset multiplot

Can anyone familiar with GNUplot or any other tool (working in linux) can help me.

Answer 1

In order to plot multiple lines in a single plot, simply put them in a single plot command like

plot 'AAA' u 1:2, 'BBB' u 1:2

There are numerous examples out there that give you a good start with gnuplot. This one for example shows how to plot multiple lines in one plot.

---

The multiplot command you are using in your script would also make it possible to have multiple plot windows like shown here. You can adjust the position of each subplot by:

set size XSIZE,YSIZE        #see `help set size` 
set origin XORIGIN,YORIGIN  #see `help set origin`

or (if you have gnuplot 4.2 or newer):

set lmargin at screen XMIN  #see `help margin`
set rmargin at screen XMAX
set tmargin at screen YMAX
set bmargin at screen YMIN