My ASCII file contains three columns: (It is output of some high energy physics simulation.)
1st column: row number(event number)is always in a pair of two i.e. if first two rows 1 and 1, then third and fourth row are 2 and 2 and so on.
2nd Column: type of particle (2 for proton and 3 for deuteron), only two types
3rd Column: theta angle (any value between 0.0 and 180.0)
What I want ? --> I want to plot theta value (third column) for proton vs for deuteron. I know how to make plot between two columns but this new task took my whole day and no results. I am using root program from root.cern.ch