Scatter plot with 3 categorical variables in gnuplot

Question

With data like this

Sensitivity,Recall,ID,Param1,Param2
0.89,0.551,run1,A1,alpha1
0.93,0.78,run1,A2,alpha2
0.54,0.76,run1,A2,alpha3
0.95,0.99,run2,A1,alpha1
0.354,0.445,run3,A1,alpha1
0.89,0.72,run4,A2,alpha1

I would like to be able to reproduce this Julia plot

Separating the plots in ID can be done by preprocessing. However, I cannot figure out how to make a color to a first column and marker shape to a second column and add them to a legend.

My first idea was to concatenate Param1 and Param2 into a single column (like "A1-alpha1"). By separating the data in two, like this :

#A2
Sensitivity,run1-alpha2,run1-alpha3,run4-alpha1
0.93,0.78,,
0.54,,0.76,
0.89,,,0.72


#A1
Sensitivity,run1-alpha1,run2-alpha1,run3-alpha1
0.89,0.551,,
0.95,,0.99,
0.354,,,0.445

The code would be

set datafile separator comma
set terminal pngcairo
set output "test2.png"
set multiplot layout 1,2
set xlabel "A1"
plot for [i=2:4] 'test2.csv' index "A1" u 1:i title columnhead(i) ps 3
set xlabel "A2"
plot for [i=2:4] 'test2.csv' index "A2" u 1:i title columnhead(i) ps 3
unset multiplot

Is there a better way (especially for having coherent labels in legend) ? Thanks,

theozh · Accepted Answer · 2023-10-30 08:37:09Z

1

As I understand you have 3 parameters and want to plot the data

into a multiplot-subplot depending on a first parameter
with a color depending on a second parameter
with a pointtype depending on a third parameter

You could do this in loops with using a filter function, i.e. if a condition is met you return the value of a certain column or otherwise NaN.

The example below is assuming that your parameters are known beforehand and are listed in some strings. Actually, there are also ways to let gnuplot create the lists of parameters automatically which might be interesting if your parameters vary from datafile to datafile.

For further information check help variable, help word, help words, help key, help keyentry. The example below can certainly be further tuned.

Script:

### plot data into multiplots with variable pointtype and color
reset session

$Data <<EOD
Sensitivity,Recall,ID,Param1,Param2
0.89,0.551,run1,A1,alpha1
0.93,0.78,run1,A2,alpha2
0.54,0.76,run1,A2,alpha3
0.95,0.99,run2,A1,alpha1
0.354,0.445,run3,A1,alpha1
0.89,0.72,run4,A2,alpha1
EOD

set datafile separator comma
set key noautotitle reverse Left
graphs = "A1 A2"
keys1  = "run1 run2 run3 run4"
keys2  = "alpha1 alpha2 alpha3"

myFilter(colD,colG,valG,colP1,valP1,colP2,valP2) = (strcol(colG) eq word(graphs,g)) && \
    (strcol(colP1) eq word(keys1,valP1)) && (strcol(colP2) eq word(keys2,valP2)) ? column(colD) : NaN
myPt(i)    = i*2+3
myColor(i) = int(word("0xff0000 0x00ff00 0x0000ff 0xff00ff 0xffff00 0x00ffff",i))

set xrange[0.3:1]
set yrange[0.4:1]

set multiplot layout 1,2 margins 0.05,0.8,0.1,0.9
    do for [g=1:words(graphs)] {
        set key at screen 0.95, 0.9-0.06*(g-1)*words(keys1)
        set title word(graphs,g)
        plot for [i=1:words(keys1)] for [j=1:words(keys2)] $Data skip 1 \
            u 1:(myFilter(2,4,g,3,i,5,j)):(myPt(j)):(myColor(i)) w p pt var ps 3 lc rgb var, \
            for [i=1:words(keys1)*(g==1)] keyentry w boxes fs solid 1.0 lc rgb myColor(i) ti word(keys1,i), \
            for [i=1:words(keys2)*(g==2)] keyentry w p ps 2 pt myPt(i) lc "grey50" ti word(keys2,i)    
    }
unset multiplot
### end of script

Result:

answered Oct 30, 2023 at 8:37

theozh

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2 Comments

alex_reader Over a year ago

Out of curiosity, how would you extract the categories from the data itself (without external tools) ? The only examples I've found have (like "Gnuplot in action") seems to hardcode them.

theozh Over a year ago

@alex_reader you need to create a list of uniqe keywords from your data. Check for example stackoverflow.com/a/75070479/7295599

Ethan · Accepted Answer · 2023-10-30 03:33:21Z

1

You can compose the legend titles and point samples separately, using the special plot component keyentry. To give an extreme case, here is a simple plot that duplicates your desired Param2 entries:

set key outside box right reverse Left samplen 1
plot sinc(x) with lines notitle, \
     keyentry with points pt 7 lc "black" title "alpha1", \
     keyentry with points pt 9 lc "black" title "alpha2", \
     keyentry with points pt "+" tc "black" title "alpha3"

answered Oct 30, 2023 at 3:33

Ethan

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