Could you, for example, have one of your craft skills filled in as carpenter, but have no ranks in it?  Being a very bad carpenter, but a carpenter nevertheless.


Question: Create heatmap with PSTricks or TikZ
Answer: You can also use pgfplots. I use the same data and the same number of point of Herbert, and the default matlab color map. You have to compile the following code with LuaLaTeX because it needs a lot of memory. It needs also a lot of time (about 2 minutes in my PC) so its better to compile it once and then insert the pdf file of your graph as an image.

\documentclass[border=10pt]{standalone}
\usepackage{pgfplots}
\usepackage{xcolor}

\pgfplotsset{compat=newest}

\begin{document}
\begin{tikzpicture}
\begin{axis}[
    colormap/jet,
    colorbar,
    view={0}{90}]
    \addplot3[surf,shader=flat] file {data-map.dat};
\end{axis}
\end{tikzpicture}
\end{document}