CODEWITHSUNDEEP
gnuplotbar-chart
hendry
hendry

Reputation: 10813

Horizontal bar chart in gnuplot

When Googling "horizontal gnuplot bar chart", the first result I could find http://www.phyast.pitt.edu/~zov1/gnuplot/html/histogram.html suggests rotating (!) the final bar chart which seems rather baroque. Nonetheless I tried the approach but the labels are cut off.

first attempt at a horizontal bar chart in gnuplot 5.2

reset
$heights << EOD
dad                     181
mom                     170
son                     100
daughter        60
EOD

set yrange [0:*]      # start at zero, find max from the data
set boxwidth 0.5      # use a fixed width for boxes
unset key             # turn off all titles
set style fill solid  # solid color boxes

set colors podo

set xtic rotate by 90 scale 0
unset ytics
set y2tics rotate by 90

plot '$heights' using 0:2:($0+1):xtic(1) with boxes lc variable

Is there a better approach?

Upvotes: 4

Views: 3160

Answers (1)

theozh
theozh

Reputation: 25684

The link you are referring to is from approx. 2009. gnuplot has developed since then. As @Christoph suggested, check help boxxyerror.

Script: (edit: shortened by using 4-columns syntax for boxxyerror, i.e. x:y:+/-dx:+/-dy)

### horizontal bar graph
reset session

$Data << EOD
dad         181
mom         170
son         100
daughter     60
EOD

set yrange [0:*]      # start at zero, find max from the data
set style fill solid  # solid color boxes
unset key             # turn off all titles

myBoxWidth = 0.8
set offsets 0,0,0.5-myBoxWidth/2.,0.5

plot $Data using (0.5*$2):0:(0.5*$2):(myBoxWidth/2.):($0+1):ytic(1) with boxxy lc var
### end of script

Result:

enter image description here

Addition:

what does 2:0:(0):2:($0-myBoxWidth/2.):($0+myBoxWidth/2.):($0+1):ytic(1) mean?

Well, it looks more complicated than it is. Check help boxxyerror. From the manual:

6 columns: x y xlow xhigh ylow yhigh

So, altogether:

  1. x take value from column 2, but not so relevant here since we will use the xyerror box
  2. y take pseudocolumn 0 which is line number starting from zero, check help pseudocolumns, but not so relevant here as well
  3. xlow (0) means fixed value of zero
  4. xhigh value from column 2
  5. ylow ($0-myBoxWidth/2.), line number minus half of the boxwidth
  6. yhigh ($0+myBoxWidth/2.), line number plus half of the boxwidth
  7. ($0+1) together with ... lc var: color depending on line number starting from 1
  8. ytic(1): column 1 as ytic label

For some reason (which I don't know) gnuplot still doesn't seem to have a convenient horizontal histogram plotting style, but at least it offers this boxxyerror workaround.

Upvotes: 10

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