Different coloured bars in gnuplot bar chart?

Question

I have a very simple dataset:

Critical 2
High 18
Medium 5
Low 14

Creating a bar chart in gnuplot out of this dataset is easy, but all the b

Answer 1

set xrange [-.5:3.5]
set yrange [0:]
set style fill solid
plot "

This takes sed and triple spaces your file so that gnuplot sees each line as a different dataset (or "index"). You can plot each index separately using index or i for short as I have done. Also, the index number is available as column(-2) which is how we get the boxes properly spaced.

Possibly a slightly more clean (gnuplot only) solution is using filters:

set xrange [-.5:3.5]
set yrange [0:]
set style fill solid
CRITROW(x,y)=(x eq "Critical") ? y:1/0
HIGHROW(x,y)=(x eq "High") ? y:1/0
MIDROW(x,y) =(x eq "Medium") ? y:1/0
LOWROW(x,y) =(x eq "Low") ? y:1/0
plot 'test.dat' u ($0):(CRITROW(stringcolumn(1),$2)):xtic(1) w boxes lc rgb "black" ti "Critical" ,\
     '' u ($0):(HIGHROW(stringcolumn(1),$2)):xtic(1) w boxes lc rgb "red" ti "High" ,\
     '' u ($0):(MIDROW(stringcolumn(1),$2)):xtic(1) w boxes lc rgb "green" ti "Medium" ,\
     '' u ($0):(LOWROW(stringcolumn(1),$2)):xtic(1) w boxes lc rgb "blue" ti "Low"

This solution also doesn't depend on any particular ordering in your datafile (which is why I prefer it slightly to the other solution. We accomplish the spacing here with column(0) (or $0) which is the record number in the dataset (in this case, the line number).