Gnuplot date/time in x axis
I have a quick question regarding dates and times in x-axis in GNUPLOT. I'll let the code do the talking:
This is my data:
#Time Data in Data out
"2013-07-22 15:59:00" 6286 3730
"2013-07-22 15:58:00" 10695 14589
"2013-07-22 15:57:00" 17868 26464
"2013-07-22 15:56:00" 18880 34012
"2013-07-22 15:55:00" 19206 41192
"2013-07-22 15:54:00" 20365 43218
"2013-07-22 15:53:00" 18459 39298
"2013-07-22 15:52:00" 3420 4686
"2013-07-22 15:51:00" 3256 4942
And this is the code that is generating the graph:
gnuplot> set title "Data usage over the last 24 hours"
gnuplot> unset multiplot
gnuplot> set xdata time
gnuplot> set style data lines
gnuplot> set term png
Terminal type set to 'png'
Options are 'nocrop font "arial,12" fontscale 1.0 size 640,480 '
gnuplot> set timefmt "%Y-%m-%d %H:%M:%S"
gnuplot> set format x "%m-%d\n%H:%M"
gnuplot> set xlabel "Time"
gnuplot> set ylabel "Traffic"
gnuplot> set autoscale y
gnuplot> set xrange ["2013-07-21 16:00":"2013-07-22 16:00"]
gnuplot> set output "datausage.png"
gnuplot> plot "C:\\Users\\blah\\Desktop\\plot.tmp" using 1:2 t "inbound" w lines, "C:\\Users\\blah\\Desktop\\plot.tmp" u 1:3 t "outbound" w lines
^
all points y value undefined!
Is the problem the space in between date and time in the x-axis? If not, what do you think could be the problem?
Answer
Gnuplot doesn't actually expect time data to be in quotes, so you have to tell it:
set timefmt '"%Y-%m-%d %H:%M:%S"'
You can put the double quotes inside single quotes as I did here, or escape the quotes:
set timefmt "\"%Y-%m-%d %H:%M:%S\""
the same applies to your xrange specification:
set xrange ['"2013-07-21 16:00"':'"2013-07-22 16:00"']
If you delete the quotes in the data file, then you can use the formatting you originally had, except the column numbers will be shifted over by 1 since the date takes up two columns without the quotes.