[Gnuplot-info] ploting if a special character exist in the line

[Mahmood N. <nt_...@ya...>]

Hi,
I have a data file which looks like this

100 10 M
150 20 M
30 40 H
50 90 M

I want to plot the second column on the rows which has 'M' in their third column (10, 20, 90). Is it possible to directly tell "plot" command to do such thing or not? Otherwise I have to preprocess the file which some languages and then feed it to gnuplot.

 
Regards,
Mahmood