gnuplot: Colour-coding specific / individual histogram bars

Question

I am using feedgnuplot to create a barchart, in order to visually show how teams compare to each other (I'd use the term benchmarking, but that's not a suitable tag here). What I would like to do is to colour one or more bars to indicate which team I'm working with.

Since pictures explain more, here is an example visually that I am attempting to reproduce:

Here we have several components: Firstly the horizontal line indicating the "group mean", and then four specific teams -- two of which are over-performing, and two of which are under.

Can you help with the red bars please?

Current attempt is produced with:

< ../gnuplot.csv /usr/bin/feedgnuplot --set 'style data histograms' --set 'style fill solid border lt -1' -xticlabels

The gnuplot command this generates is:

set grid
set boxwidth 1
histbin(x) = 1 * floor(0.5 + x/1)
set style data histograms
set style fill solid border lt -1
plot '-'    using 3:xticlabels(2) notitle  
2 "E" 8
3 "H" 7
4 "B" 6
5 "F" 5
6 "A" 4
7 "D" 3
8 "C" 2
e

How does your input data look like? Can you please provide some example data? How do you specify the 4 bars, by x-value? What have you tried so far? How does your gnuplot script look like? — theozh, Jan 26 '23 at 18:27
How to specify the bars? Any way possible (unsure of where to start). Ideally, as simple as possible. This is to be done via shell script. I can easily add an extra column to the data, with a boolean value or similar. — Phil, Jan 26 '23 at 21:53

score 0 · Accepted Answer · answered Jan 27 '23 at 07:15

From your example I don't see why you would need plotting style histogram. A simple bar chart with conditional color should be sufficient.

simply define a function based on your condition for bar coloring and use variable linecolor (check help lc variable).
if you want to plot the statistical mean value, use stats (check help stats).
the example below has just two columns column 1 text and column 2 numbers. Since you need an x-value for the bars, you take pseudocolumn 0, which is basically the row number with 0-based index (check help pseudocolumns).

Script:

### bar chart with conditional color
reset session

# create some random test data
set table $Data
    set samples 26
    y0 = 900
    alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    plot '+' u (alphabet[$0+1:$0+1]):(y0=y0-rand(0)*50) w table
unset table

myColor(col) = (_s=strcol(col), _s eq "C" || _s eq "J" || _s eq "T" || _s eq "X" ? \
                 0xff3333 : 0x3333ff)

set offset 1,1,0,0
set key noautotitle
set style fill solid 0.5
set yrange[0:1000]

stats $Data u 0:2 nooutput   # get the mean value into variable STATS_mean_y
set label 1 at STATS_max_x, STATS_mean_y sprintf("mean=%.1f",STATS_mean_y) offset 0,0.7 right

plot $Data u 0:2:(myColor(1)):xtic(1) w boxes lc rgb var, \
     STATS_mean_y w l lw 2 lc "web-green"
### end of script

Result:

gnuplot: Colour-coding specific / individual histogram bars

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