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histogram bar colors

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  histogram bar colors bryan <bryanlepore@gmail.com> - 2013-09-01 11:22 -0700
    Re: histogram bar colors sfeam <sfeam@users.sourceforge.net> - 2013-09-01 16:46 -0700
      Re: histogram bar colors bryan <bryanlepore@gmail.com> - 2013-09-01 19:31 -0700
        Re: histogram bar colors sfeam <sfeam@users.sourceforge.net> - 2013-09-03 12:40 -0700

#2012 — histogram bar colors

[ gnuplot 4.6 patchlevel 0 - yes I can upgrade this ASAP]
[ Ubuntu 12.04.3 LTS ]
[ misc downstream programs]

I am wondering how to color particular bars a different color than a default. my working script and data to plot fractions as a histogram is copy/pasted below. AFAIK a rather general histogram setup is employed. but specifically, the script uses:

plot 'test_01sep13a.dat' u 3:xticlabel(1)

to actually plot the data.

in the example, there are two particular bars that should be at 500 and 1000 in some alternate color. so the output plot would, for example, have all the bars for the fruit (see data) in the color red, and the bars for the numbers (500 and 1000) black. the idea is the bars for the numbers would stand out. FYI this is to connect the fractional value with the count ("how many") value.

this script appears to be close to what I am looking for:

http://gnuplot.sourceforge.net/demo/histograms.2.gnu

but the data is plotted in a different way... I admit I could learn more about the above syntax I am already using.

here's the script and data:
-------------------------------------------------------
set title "compare fruit categories"
set xtics 1 out
set grid 
set key left top 
unset label 
set format y "%3.3f"
set xlabel "category" ; set ylabel "fraction " rotate by -90
set style data histogram
set style fill solid border -1 
set style histogram
set xtics nomirror rotate by -90
set ytics rotate by -90
set bars back 
plot 'test_01sep13a.dat' u 3:xticlabel(1) notitle
#------------------------------------------------------------------------
#test_01sep13a.dat:
banana     53.08   0.000396244
apple      160     0.00119441
500        500     0.00373252
lemon      804.65  0.00600674
tangerine  956.77  0.00714233
kiwi       977.38  0.00729618
1000      1000     0.00746504
starfruit 1022.31  0.00763158
orange    1061.76  0.00792608
#------------------------------------------------------------------------

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#2013

bryan wrote:

> [ gnuplot 4.6 patchlevel 0 - yes I can upgrade this ASAP]
> [ Ubuntu 12.04.3 LTS ]
> [ misc downstream programs]
> 
> I am wondering how to color particular bars a different color than a
> default. my working script and data to plot fractions as a histogram
> is copy/pasted below. AFAIK a rather general histogram setup is
> employed. but specifically, the script uses:
> 
> plot 'test_01sep13a.dat' u 3:xticlabel(1)
> 
> to actually plot the data.
> 
> in the example, there are two particular bars that should be at 500
> and 1000 in some alternate color. so the output plot would, for
> example, have all the bars for the fruit (see data) in the color red,
> and the bars for the numbers (500 and 1000) black. the idea is the
> bars for the numbers would stand out. FYI this is to connect the
> fractional value with the count ("how many") value.
> 
> this script appears to be close to what I am looking for:
> 
> http://gnuplot.sourceforge.net/demo/histograms.2.gnu
> 
> but the data is plotted in a different way... I admit I could learn
> more about the above syntax I am already using.
> 
> here's the script and data:
> -------------------------------------------------------
> set title "compare fruit categories"
> set xtics 1 out
> set grid
> set key left top
> unset label
> set format y "%3.3f"
> set xlabel "category" ; set ylabel "fraction " rotate by -90
> set style data histogram
> set style fill solid border -1
> set style histogram
> set xtics nomirror rotate by -90
> set ytics rotate by -90
> set bars back
> plot 'test_01sep13a.dat' u 3:xticlabel(1) notitle
> #------------------------------------------------------------------------
> #test_01sep13a.dat:
> banana     53.08   0.000396244
> apple      160     0.00119441
> 500        500     0.00373252
> lemon      804.65  0.00600674
> tangerine  956.77  0.00714233
> kiwi       977.38  0.00729618
> 1000      1000     0.00746504
> starfruit 1022.31  0.00763158
> orange    1061.76  0.00792608
> #------------------------------------------------------------------------

You don't really need the "with histograms" style for this plot.
It will be easier to show "with boxes".

Add the following lines to your script:

barcolor(n) = strstrt(strcol(n), "0") ? 2 : 3
set boxwidth 0.2 absolute

and replace the plot command with

plot 'test_01sep13a.dat'  u 0:3:(barcolor(1)):xticlabel(1) \
      with boxes fillcolor variable notitle

The key point here is to specify "fillcolor variable",
which says that the color will be determined based on the
contents of some column in the input file.  Since your
data file does not have a column containing colors per se,
I defined a coloring function that chooses either 
color 2 or color 3 based on whether the string in data column 1
contains the digit "0" or not.  Much fancier coloring schemes
are possible if you want to go to the trouble.

	Ethan
   

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#2014

On Sunday, September 1, 2013 7:46:22 PM UTC-4, sfeam wrote:
> It will be easier to show "with boxes".
> 
> Add the following lines to your script:
> 
> barcolor(n) = strstrt(strcol(n), "0") ? 2 : 3
> 
> set boxwidth 0.2 absolute
> 
> and replace the plot command with
> 
> plot 'test_01sep13a.dat'  u 0:3:(barcolor(1)):xticlabel(1) \
> 
>       with boxes fillcolor variable notitle
> 
> The key point here is to specify "fillcolor variable",

thats interesting, and precisely what I was looking for - thanks a lot. also seems to be a good reason to get the latest patchlevel.

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#2019

bryan wrote:

> On Sunday, September 1, 2013 7:46:22 PM UTC-4, sfeam wrote:
>> It will be easier to show "with boxes".
>> 
>> Add the following lines to your script:
>> 
>> barcolor(n) = strstrt(strcol(n), "0") ? 2 : 3
>> 
>> set boxwidth 0.2 absolute
>> 
>> and replace the plot command with
>> 
>> plot 'test_01sep13a.dat'  u 0:3:(barcolor(1)):xticlabel(1) \
>> 
>>       with boxes fillcolor variable notitle
>> 
>> The key point here is to specify "fillcolor variable",
> 
> thats interesting, and precisely what I was looking for - thanks a lot.
> also seems to be a good reason to get the latest patchlevel.

Oops, I had forgotten that some versions had a bug in recognizing
the "fillcolor variable" keyword.  Here is a slight variation that
should work also on older gnuplot versions starting from 4.4.


  barcolor(n) = strstrt(strcol(n), "0") ? 0xff0000 : 0x0000ff

  plot 'test_01sep13a.dat'  u 0:3:(barcolor(1)):xticlabel(1) \
       with boxes notitle lt rgb variable

The two colors in question are specified as 24-bit RGB colors
in hexadecimal form, pure red and pure blue in this case.

	Ethan

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