Re: heat map ?

[Daniel J S. <dan...@ie...>]

On 04/22/2016 02:46 AM, Valerio Schiavoni wrote:
> Hello,
> i've been trying to make an heat map that looks like the one in this
> blog entry
> https://learnr.wordpress.com/2010/01/26/ggplot2-quick-heatmap-plotting/
> Unfortunately they don't use gnuplot.
>
> My attempt so far produces a poor result, i think because I'm not using
> the right approach.
>
> Here's my current version:
>
> set term pdfcairo
> set output "latency_heat.pdf"
> load "../styles.inc"
> set size 0.9,1.0
> set lmargin 15
> set rmargin 20
> set pm3d #interpolate 0,100
> set view map scale 1
> set style func pm3d
> set style data pm3d;
> set dgrid3d
> set pal defined ( 0 0 0 0, 1 1 1 1 )
> set tic scale 0
> set cblabel "Latency (ms)"
> set datafile separator comma
> splot "heatmap_latencies.txt" matrix rowheaders columnheaders using
> 1:2:3 with image title ""
>
> Where the input file is:
>
> ,One,Two,Three
> a,675.0, 1177.0, 1975.0
> b,744.0, 13908.0, 20191.0
> c,1767.0, 4374.0  ,5165.0
> d,678.0, 1101.0  ,1888.0
> e, 771.0, 13842.0 ,18648.0
> f, 1372.0, 4264.0  ,5187.0
> g,753.0 , 1541.0  ,1729.0
> h,791.0 , 5832.0  ,20528.0
> i,1310.0, 1225.0  ,5436.0
> l,747.0,  1516.0  ,2118.0
> m,825.0 , 16719.0 ,0
> n,1341.0, 4427.0 ,9040.0
>
>
> Any idea on how to improve this ?
>
> Thanks !
> --
> Valerio

You are trying to do something like the blue-tinted images Valerio? 
What I see from your example is a greyscale which is sort of the right 
idea, and I think you should be able to achieve most of the other 
properties in those blue-tinted images.  You can

1) Change the color map (palette) from greyscale to one that has the 
blue tint.  (And perhaps there is already a predefined color map that is 
close.)

http://gnuplot.sourceforge.net/demo_5.0/heatmaps.html

2) Apply a non-90 degree rotation to the x-axis annotation.

http://gnuplot.sourceforge.net/demo_5.0/tics.html

3) Draw individual white lines across the axes to create the borders 
between individual elements.

http://gnuplot.sourceforge.net/demo_5.0/rgb_variable.html

Look through some of the demos here for ideas:

http://gnuplot.sourceforge.net/demo_5.0/
http://gnuplot.sourceforge.net/demo_5.1/

Dan