Automatic coloring of numbers according to size

Question

Scientific talks have their own culture, reporting the results, typically for me, in a table of the following form

1.7333    1.6472    1.5418    1.4682    1.5740
1.1525    1.2878    1.2652    1.3511    1.5102
1.2181    1.1500    1.2220    1.2425    1.5699
0.9786    1.1051    1.1472    1.3096    1.6757
0.9569    0.9190    1.0433    1.2924    1.4867

There is clearly a(n almost perfectly) monotonic pattern for rows and columns. Now for the naked eye, this is not the most quick way of capturing informing.

I would like numbers that bigger in absolute value, to appear differently (either green vs red or light vs dark) than smaller numbers, such that the pattern becomes clear instantly.

Is there a way of programming this in LaTeX?

Answer 1

You can use the collcell package to process an entry based on the numeric value. Below I have defined the R column type to apply a percent of black based on the numerical value.

Notes:

• One could adapt this to apply different colors based on the size of the number and perhaps that would yield even better results. For instance, use a different color based on which quartile the number is in (<25% use gray, 25-50% use brown, 50-75% use black, >75 use red).

Code:

\documentclass{article}
\usepackage{xcolor}
\usepackage{pgf}
\usepackage{collcell}

% This selects the amount of color to use
\newcommand*{\MinNumber}{0.5}%
\newcommand*{\MaxNumber}{1.8}%

\newcommand{\ApplyGradient}[1]{%
    \pgfmathsetmacro{\PercentColor}{100.0*(#1-\MinNumber)/(\MaxNumber-\MinNumber)}
    \textcolor{black!\PercentColor}{#1}
}
\newcolumntype{R}{>{\collectcell\ApplyGradient}{r}<{\endcollectcell}}

\begin{document}
\begin{tabular}{R R R R R}
1.7333 & 1.6472 & 1.5418 & 1.4682 & 1.5740 \\
1.1525 & 1.2878 & 1.2652 & 1.3511 & 1.5102 \\
1.2181 & 1.1500 & 1.2220 & 1.2425 & 1.5699 \\
0.9786 & 1.1051 & 1.1472 & 1.3096 & 1.6757 \\
0.9569 & 0.9190 & 1.0433 & 1.2924 & 1.4867 \\
\end{tabular}
\end{document}

Answer 2

I suggest the package pgfplotstable. With the following code you test if the contents of the cell is lower than a specified \bordervalue (I took 1.4). Based on the result the number will be printed in green or red.

At the moment the input isn't tested if it is a number or not. So be careful.

   postproc cell content/.style={@cell content={%
    \pgfmathparse{int(less(#1,\bordervalue))}
    \ifnum\pgfmathresult=1
       \color{red} #1
    \else
       \color{green!60!black} #1
    \fi

\documentclass[]{scrartcl}%
\usepackage{pgfplotstable}
\begin{document}
\def\bordervalue{1.4}
\pgfplotstabletypeset[row sep=\\,col sep=&,assume math mode=false,
   postproc cell content/.style={@cell content={%
    \pgfmathparse{int(less(#1,\bordervalue))}
    \ifnum\pgfmathresult=1
       \color{red} #1
    \else
       \color{green!60!black} #1
    \fi
}},]
{%
1.7333    & 1.6472    & 1.5418    & 1.4682    & 1.5740  \\
1.1525    & 1.2878    & 1.2652    & 1.3511    & 1.5102  \\
1.2181    & 1.1500    & 1.2220    & 1.2425    & 1.5699  \\
0.9786    & 1.1051    & 1.1472    & 1.3096    & 1.6757  \\
0.9569    & 0.9190    & 1.0433    & 1.2924    & 1.4867  \\
}
\end{document}