How to convert epoch to human readable time properly in gnuplot

Question

I have the following snippet to have a graph output via gnuplot.

set datafile separator ","

set title "Memory"
set xlabel "Values"
set ylabel "Date"
set ydata time
set timefmt "%H"
set format y "%d/%m/%Y"
set key left top
set grid

plot 'memory-memory-buffered_combined' using 0:2 titl "1" with lines,\
     'memory-memory-cached_combined' using 0:2 title "2" with lines
cat 
pause -1

However, when I have the result it starts from 1970.

The first 5 lines of the csv I am reading;

epoch,value
1478193413.596,72910
1478193473.412,134432
1478193413.158,65449
1478193411.929,60157

So, it is actually November 2016.

Which part of my script should be different?

Answer 1

Your main issue is that your time data is in the first column of the file, however you want to use that as y-data rather than x-data. So you need to plot using 2:1

The second issue is that your timefmt specifier needs to be %s (epoch time: this is the format of your input data) rather than %H.

So

set datafile separator ","

set title "Memory"
set xlabel "Values"
set ylabel "Date"
set ydata time
set timefmt "%s"
set format y "%d/%m/%Y"
set key left top
set grid

plot 'data.csv' using 2:1 title "1" with lines

resulting in