# Using gnuplot to plot large data set under Windows XP

**URL:** <https://www.ruby-forum.com/t/using-gnuplot-to-plot-large-data-set-under-windows-xp/153053>\
**Category:** Ruby\
**Created:** [November 11, 2008, 4:28pm UTC](https://www.ruby-forum.com/t/using-gnuplot-to-plot-large-data-set-under-windows-xp/153053 "2008-11-11T16:28:17Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![swabianeagle](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/71c47a/32.png) [@swabianeagle](https://www.ruby-forum.com/u/swabianeagle)\
**Post date:** [November 11, 2008, 4:28pm UTC](https://www.ruby-forum.com/t/using-gnuplot-to-plot-large-data-set-under-windows-xp/153053/1 "2008-11-11T16:28:17Z")

</div>

Hi,

I’ve been using gnuplot for the last little while to plot data and I  
really like it. So far I’ve been processing my data with ruby and  
generated a csv file, that I then read from a gnuplot script.  
This works fine, but I want to take out the extra step of going through  
a csv file.  
I’ve been trying to use the gnuplot gem (v. 2.2), however I’ve been  
running into problems with large data sets.

Here are two sample programs, that do essentially the same. The  
difference is that the first one calls gnuplot directly, whereas the  
second one generates a gnuplot script file, that can be used by gnuplot.

Version 1: Calling gnuplot directly from ruby.  
(Note my gnuplot path is: “c:/Program Files/gnuplot/bin/pgnuplot.exe”)

Gnuplot.open do |gp|  
Gnuplot::Plot.new( gp ) do |plot|  
x = (0…1500).collect { |v| v.to\_f }  
y = x.collect { |v| v \*\* 2 }  
plot.data =[Gnuplot::DataSet.new( [x, y] ) do |ds|  
ds.with = “linespoints”  
ds.notitle  
end  
]  
end  
end

Version 2: Generating a gnuplot script, that afterward can be called by  
gnuplot

File.open( “gnuplot.dat”, “w”) do |gp|  
Gnuplot::Plot.new( gp ) do |plot|  
x = (0…1500).collect { |v| v.to\_f }  
y = x.collect { |v| v \*\* 2 }  
plot.data = [Gnuplot::DataSet.new( [x, y] ) { |ds|  
ds.with = “linespoints”  
ds.title = “Array data”  
}]  
end  
end

Unfortunately the first version doesn’t really work. For some reason the  
data gets corrupted. It’s almost like gnuplot can’t keep up fast enough  
reading the data. I’ve been playing around with the array size. For  
smaller data sets (a few hundred points) version 1 works fine, but as  
array size increases to 700-800 points I see this problem happening.

I can work with version 2 for now, but it seems a bit like a kludge to  
me, ideally I’d like to not go through an intermediate file.

Any ideas would be appreciated.

Thanks,  
Armin