merge for datablocks

[Daniel M. <mon...@ku...>]

Hi,

I just read about the patch for a "merge" command 
(https://sourceforge.net/p/gnuplot/patches/615/) that would allow 
merging the results of two plot commands into a single datablock that 
could then be used for a subsequent plot that needed both results. I 
don't think this was added to gnuplot. I tried "merge" in my current 
gnuplot version (5.2.8) and I get an "invalid command" reply.

It sounds it would be useful for combining data from different 
datablocks or files.
My use case for this would be creating a plot of the percentage of 
points in each interval that have a specific values from another column.

For example, for a file called "datafile.txt", containing values between 
0 and 1 in COL1 and a binary label in COL2:
COL1 COL2
0.1    0
0.2    1
0.1    1
0.33    0
0.4    1
1.0    0
0.9    0
0.12    1
0.13    1
0.13    0
0.89    1
0.88    0
....

A "merge" command would help to plot the following curve:

- percentage of points having COL1 between [0.0, 0.1] and COL2==1
- percentage of points have COL1 in the range [0.1,0.2] and COL2==1
- percentage of points have COL1 in the range [0.2,0.3] and COL2==1
and so on.

Currently, I am able to achieve this with "table" and "smooth frequency":
--------------------------------------------------------------------------------
# define function for binning data
binwidth = 0.1
bin(val) = binwidth * floor(val/binwidth)

# save total counts in each bin
set table "fileA"
plot "datafile.txt" using (bin(column("COL1"))):(1.0) smooth frequency 
with points

# save counts in each bin with a specific label
set table "fileB"
plot "datafile.txt" using (bin(column("COL1"))):(column("COL2") > 0 ? 
1.0 : 0.0) smooth frequency with points
unset table

# plot the percentage of dots with label "1" in each bin of width 0.1
plot "< paste fileA fileB" using 1:($5/$2) with linespoints
--------------------------------------------------------------------------------


Clearly this could be achieved pre-processing the data externally, but 
it looks like that the proposed "merge" command for datablocks would be 
a useful tool here.
It would simplify this without the need for writing data to files and 
reading it back.


Thank you,

__________________________________
Daniel Montezano
Center for Computational Biology
University of Kansas
Lawrence, KS 66045