gnuplot time axis from two different columns
<p>I'm trying to plot some data from a four columns file. The first one is the numbre of data the second one is the year the third one are months and the final one are values of temperature. The thing is that I woul like that my x axis takes a date from the second and the third columns.<br>
The text file look like this:</p>

<p>1      1990         2                  265.78945923<br>
2      1990         3                  260.53842163<br>
3      1990         4                  265.00366211<br>
4      1990         5                  277.61206055<br>
5      1990         6                  284.72595215<br>
6      1990         7                  291.54879761<br>
7      1990         8                  293.61392212<br>
8      1990         9                  288.47149658<br>
9      1990        10                  284.55172729<br>
12     1991         1                  285.98762388<br>
13     1991         2                  283.47484293</p>

<p>I'm using a code like this:</p>

<pre><code>set xdata time
set timefmt '%Y %m'
plot 'datafile' u 2:4
</code></pre>

<p>But it doesn't work. I woul like to have on my x axis the year and the months.<br>
All help appreciated! Thanks</p>