I have two different files to plot in the gnuplot. they use a) different separator b) different time on x-axis
hence for each of them to plot separately I need to pass
set datafile separator
set timefmt
I would like to impose/overlay both data in a single graph such, that they are aligned with time
how could I do this?
The problem with the different separators can be addressed by using the format after the using modifier to specify a different separator for each file, e.g.:
plot 'file1.dat' u 1:2 '%lf,%lf'
plots a two column file with comma separator. See help\using for some more detail.
I am not expert of time formats, so I don't know how to deal with the timestamp format problem. But maybe you can use some function like strftime(). I never tried it, but it seems to me it does what you need.
You're right, you will need to pass set datafile separator and set timefmt once per file. You can do it like this:
set terminal <whatever>
set output <whatever.wht>
set xdata time # tell gnuplot to parse x data as time
set format x '%F' # time format to display on plot x axis
set datafile separator ' ' # separator 1
set timefmt '%F' # time format 1
plot 'file1'
set datafile separator ',' # separator 2
set timefmt '%s' # time format 2
replot 'file2'
The replot command by itself replots the previous line, and if you specify another line to be plotted that will go on top of the first one like I did here.
replot will re-read the file in the previous command, but now the datafile separator isn't right, so gnuplot won't find any points (or at least not the right one).It seems to me that you have 2 options. The first is to pick a datafile format and beat both datafiles into that format, maybe using awk:
plot '<awk "-f;" "{print $1,$2}" data1' using 1:2 w lines,\
'data2' using 1:2 w lines
*Note, your awk command will almost certainly be different, this just shows how to use awk in an inline pipe.
Your second option is to use multiplot with explicit axes alignment:
set multiplot
set xdata time
set datafile sep ';' #separator for first file
set timefmt "..." #time format for first file
set lmargin at screen 0.9
set rmargin at screen 0.1
set tmargin at screen 0.9
set bmargin at screen 0.1
unset key
plot 'data1' u 1:2 w lines ls 1 nontitle
set key #The second plot command needs to add both "titles" to the legend/key.
set datafile sep ',' #separator for second file
set timefmt "..." #time format for second file
unset border
unset xtics
unset ytics
#unset other stuff that you set to prevent it from being plotted twice.
plot NaN w lines ls 1 title "title-for-plot-1", \
'data1' u 1:2 w lines ls 2 title "title-for-plot-2"
The plot NaN trick is only necessary if you want to have things show up correctly in the legend. If you're not using a legend, you can not worry about it.
This works for me :
reset
set term pngcairo
set output 'wall.png'
set xlabel "Length (meter)"
set ylabel "error (meter)"
set style line 1 lt 1 linecolor rgb "yellow" lw 10 pt 1
set style line 2 lt 1 linecolor rgb "green" lw 10 pt 1
set style line 3 lt 1 linecolor rgb "blue" lw 10 pt 1
set datafile separator ","
set key
set auto x
set xtics 1, 2, 9
set yrange [2:7]
set grid
set label "(Disabled)" at -.8, 1.8
plot "file1.csv" using 1:2 ls 1 title "one" with lines ,\
"file2.csv" using 1:2 ls 2 title "two" with lines ,\
"file3.csv" using 1:2 ls 3 title "three" with lines
set output
