[Gnuplot-info] input date format: week numbers + year

[Sebastien K. <seb...@ya...>]

Dear gnuplot users and developpers,

I want to plot a datafile were the x-axis data values are the week numbers of a year, 
stored in the datafile. I am producing the datafile from some other application, so I 
can easily change what is stored in it, if needed.

My problem is that for a given year (from september to july), week 2 is after week 
51. If I plot the following toy file:

# week;year;value
50;2013;10
51;2013;11
2;2014;12

with:
plot "datafile" using $1:$3
then week 2 will appear *before* week 51, and what I want on the x-axis is:

50   51   2

I checked out the "set format" command, but it seems to be only about format 
rendering, my problem is about input date format.

Any hint on the easiest way to do this ?

Thank you