The conditional plotting with gnuplot

Asked Dec 11 '18 at 01:55

Active Dec 19 '18 at 17:56

Viewed 68 times

I'm new on gnuplot.

Can anyone help me plot with condition?

I know there is something like if statement, but I have no idea

how to deal with it and it looks like it's not appropriate to what I want to do.

I have a data set like this,

6  1   3   -9  
7  2   2   -9      
5  2   2   4   
4  3   5   5  
5  4   1   3  
3  4   1   -9

So I have 6 rows and 4 columns.

What I want to do is to plot a graph using ($1-$2):($3-$4),

but if an element in column 4 is -9, then the rows that have -9 won't be plotted.

Therefore, the graph will only show the data of row 3,4, and 5.

Plot 'text.txt' u ($1-$2):($3-$4)

How can I apply that concept on the above command?

edited Dec 19 '18 at 17:56

Cheong Sik Feng

asked Dec 11 '18 at 01:55

snam

Add this line: `set datafile missing '-9'` – Michael Dec 11 '18 at 06:33
plot 'text.txt' u ($1-$2):($4 != -9 ? $3-$4 : NaN) – user8153 Dec 11 '18 at 09:04
Like user8153 said ^. The structure of a conditional in gnuplot is as follows : ` ? : `. It's actually the same as in C++. In this specific example, when gnuplot encounters NaN (i.e. whenever the value in the fourth column is -9), it won't plot anything. – Alex Dec 11 '18 at 09:16
https://stackoverflow.com/q/30522035/2604213 – Christoph Dec 11 '18 at 21:31
Thank you guys! That's what I was looking for! – snam Dec 12 '18 at 01:19

0 Answers0