Plotting Condition Lines

Question

Suppose I have the following data:

"1,5"
"2,10"
""
"3,4"
"4,2"
""
"5,6"
"6,10"

I want to graph this using gnuplot with a line between each condition, similar to this display:

How might this be accomplished? I have looked into gridlines, but that does not seem to suit my need. I am also looking for a solution that will automatically draw condition / phase lines between each break in the data set.

Are the "condition lines" the vertical dashed lines in the plot? If yes, you could get some ideas from here: https://stackoverflow.com/questions/4457046/how-do-i-draw-a-vertical-line-in-gnuplot — user000001, Dec 28 '18 at 06:51

theozh · Answer 1 · 2022-09-12T12:21:34.290

As mentioned in the comments and explained in the linked question and its answers, you can draw arbitrary lines manually via set arrow ... (check help arrow).

However, if possible I don't want to adjust the lines manually every time I change the data or if I have many different plots. But, hey, you are using gnuplot, so, make it automated! To be honest, within the time figuring out how it can be done I could have changed a "few" lines and labels manually ;-). But now, this might be helpful for others.

The script below is written in such a way that it doesn't matter whether you have zero, one or two or more empty lines between the different blocks.

Comments:

the function valid(1) returns 0 and 1 if column(1) contains a valid number (check help valid).
the vertical lines are plotted with vectors (check help vectors). The x-position is taken as average of the x-value before the label line and the x-value after the label line. The y-value LevelY is determined beforehand via stats (check help stats).
the labels are plotted with labels (check help labels) and positioned at the first x-value after each label line and at an y-value of LevelY with an offset.

Script:

### automatic vertical lines and labels
reset session

$Data <<EOD
Baseline
  1  10.0
  2  12.0
  3  10.5
  4  11.0   # zero empty lines follow
Treatment
  5  45.0
  6  35.0
  7  32.5
  8  31.0   # one empty line follows

Baseline
  9  14.0
 10  12.8
 11  12.0
 12  11.3   # two empty lines follow


Treatment
 13  35.0
 14  45.0
 15  45.0
 16  37.0
EOD

set offset 1,1,1,1
set border 3
set title "Student Performance" font ",14"
set xlabel "Sessions"
set xtics 1 out nomirror
set ylabel "Number of Responses"
set yrange [0:]
set ytics out nomirror
set key noautotitle
set grid x,y

stats $Data u 2 nooutput
LevelY = STATS_max    # get the max y-level

getLinePosX(col) = (v0=v1,(v1=valid(col))?(x0=x1,x1=column(1)):0, v0==0?(x0+x1)/2:NaN)
getLabel(col)    = (v0=v1,(v1=valid(col))?0:(h1=strcol(1),h0=h1),column(1))

plot x1=NaN $Data u (y0=(valid(1)?$2:NaN),$1):(y0) w lp pt 13 ps 2 lw 2 lc "red", \
     x1=v1=NaN '' u (getLinePosX(1)):(0):(0):(LevelY) w vec nohead lc "black" lw 1.5 dt 2, \
        v1=NaN '' u (getLabel(1)):(LevelY):(sprintf("%s",v0==0?h0:'')) w labels left offset 0,1.5 font ",12"
### end of script

Result:

Plotting Condition Lines

1 Answers1