Partially coloring cell background to fake histogram

Question

Excel has a cool feature called "data bar" conditional formatting that allows the user to partially fill a cell background to create histograms based on cell contents. Here is a screen clip example from a workbook:

I'm looking for a TiKZ, minipage, or some other solution that will allow me to only partially color the background of a cell. I've played around with a few options without success.

Here is a minimum working example using \cellcolor from the xcolor package.

\documentclass{article}
\usepackage[table]{xcolor}% http://ctan.org/pkg/xcolor
\begin{document}
\begin{tabular}{l|c|r}
  \hline
  91.41 & \cellcolor{green!25}90.81 & 38.76 \\
  \cellcolor{green!25}98.75 & 13.82 & 94.62 \\
  57.11 & \cellcolor{green!25}51.21 & \cellcolor{green!25}42.84 \\
  \hline
\end{tabular}
\end{document}

The code above produces:

In a perfect world, I'd have a macro like \partialcellcolor{green!25}{0.41\linewidth} or whatever to specify that the color extends across 41% of the cell. I use "R" to generate the table, so I'll let it do the math as it scripts the latex code.

Any suggestions?

Answer 1

Update with minimal and maximal values

Minimal values are only usable when negative values are disabled (\negativeValuesfalse).

Code

\documentclass{article}
\usepackage[table]{xcolor}% http://ctan.org/pkg/xcolor
\usepackage{tikz,array,collcell}
\usetikzlibrary{calc}
\pgfdeclarelayer{background}
\pgfdeclarelayer{main}
\pgfsetlayers{background,main}
\newif\ifnegativeValues
\newcommand{\tikzMe}[1]{%
  \tikz[baseline]{
    \node[anchor=base,text width=\minWidth,align=\alignment,inner sep=0pt,inner xsep=\tabcolsep,outer sep=0pt] (n) {\strut$#1$};
    \begin{pgfonlayer}{background}
        \ifnegativeValues
            \pgfmathparse{#1<0?"red!50":"green!25"}
            \edef\color{\pgfmathresult}
        \else
            \def\color{green!25}
        \fi
       \pgfmathparse{abs((#1-\minValue)/(\maxValue-\minValue))}
       \fill[color=\color] (n.north west) rectangle ($(n.south west)!\pgfmathresult!(n.south east)$);
    \end{pgfonlayer}
  }
}
%\negativeValuestrue % inserts a minus sign for the minWidth and use red for negative values
\negativeValuesfalse % doesn't insert a minus sign, uses only green

\newcolumntype{H}[3]{%
  @{}
  >{%
    \ifx\\#1\\\def\alignment{right}\else\def\alignment{#1}\fi%
    \ifnegativeValues\def\minValue{0.}\else\def\minValue{#2}\fi%
    \def\maxValue{#3}%
    \def\minWidth{\widthof{$\ifnegativeValues-\fi#3$}}%
    \collectcell\tikzMe%
  }c<{\endcollectcell}
  @{}}
\begin{document}
\begin{tabular}{|H{}{10.}{100.00}|H{}{2.}{105.00}|H{}{0.}{150.00}|}
    \hline
    10.0   & 2.00   & 0.00   \\
    15.49  & 13.82  & 100.00 \\
    100.00 & 105.00 & 150.00 \\ \hline
\end{tabular}
\end{document}

Output

Old answer

Code

\documentclass{article}
\usepackage[table]{xcolor}% http://ctan.org/pkg/xcolor
\usepackage{tikz,array,collcell}
\usetikzlibrary{calc}
\pgfdeclarelayer{background}
\pgfdeclarelayer{main}
\pgfsetlayers{background,main}
\newcommand*{\minWidth}{\widthof{$-100.00$}}
\newcommand*{\maxValue}{100}
\newcommand{\tikzMeL}[1]{\tikzMe{#1}{left}}
\newcommand{\tikzMeC}[1]{\tikzMe{#1}{center}}
\newcommand{\tikzMeR}[1]{\tikzMe{#1}{right}}
\newcommand{\tikzMe}[2]{%
  \tikz[baseline]{
    \node[anchor=base,text width=\minWidth,align=#2,inner sep=0pt,inner xsep=\tabcolsep,outer sep=0pt] (n) {\strut$#1$};
    \begin{pgfonlayer}{background}
       \pgfmathparse{#1<0?"red!50":"green!25"}
       \edef\color{\pgfmathresult}
       \pgfmathparse{abs(#1/\maxValue)}
       \fill[color=\color] (n.north west) rectangle ($(n.south west)!\pgfmathresult!(n.south east)$);
    \end{pgfonlayer}
  }
}
\newcolumntype{L}{@{}>{\collectcell\tikzMeL}c<{\endcollectcell}@{}}
\newcolumntype{C}{@{}>{\collectcell\tikzMeC}c<{\endcollectcell}@{}}
\newcolumntype{R}{@{}>{\collectcell\tikzMeR}c<{\endcollectcell}@{}}
\begin{document}
\begin{tabular}{|L|C|R|}        \hline
    91.41  & 100.00 & 38.76   \\
    -15.49 & -13.82 & -100.00 \\
    57.11  & 51.21  & -42.84  \\ \hline
\end{tabular}
\end{document}

Output

Answer 2

Another sans-TikZ alterantive:

\documentclass{article}
\usepackage[table]{xcolor}% http://ctan.org/pkg/xcolor
\usepackage[nomessages]{fp}% http://ctan.org/pkg/fp
\newcommand{\maxnum}{100.00}
\newlength{\maxlen}
\newcommand{\databar}[2][green!25]{%
  \settowidth{\maxlen}{\maxnum}%
  \addtolength{\maxlen}{\tabcolsep}%
  \FPeval\result{round(#2/\maxint,4)}%
  \rlap{\color{green!25}\hspace*{-.5\tabcolsep}\rule[-.05\ht\strutbox]{\result\maxlen}{.95\ht\strutbox}}%
  \makebox[\dimexpr\maxlen-\tabcolsep][r]{#2}%
}
\begin{document}

\begin{tabular}{*{3}{|l}|}
  \hline
  \databar{91.41} & \databar {90.81} & \databar{38.76} \\
  \databar{98.75} & \databar {13.82} & \databar{94.62} \\
  \databar{57.11} & \databar {51.21} & \databar{42.84} \\
  \databar{20.00} & \databar{100.00} & \databar{80.00} \\
  \hline
\end{tabular}
\end{document}

You provide the maximum number (as a macro \maxnum) that is used to calculate the percentage fill. Calculations are performed using fp.

---

Using this variation of \databar provides a fill that leaves a (barely visible) .5\arrayrulewidth on either side of the table cell. This is just to avoid any kind of artefacts caused by the viewer. The TikZ solution doesn't show this since it draws the coloured boxes in the background (almost as an underlay) of the entire table, so the rules overdraw any overlap:

%...
\newcommand{\databar}[2][green!25]{%
  \settowidth{\maxlen}{\maxnum}%
  \addtolength{\maxlen}{\dimexpr2\tabcolsep-\arrayrulewidth}%
  \FPeval\result{round(#2/\maxnum,4)}%
  \rlap{\color{green!25}\hspace*{\dimexpr-\tabcolsep+.5\arrayrulewidth}\rule[-.05\ht\strutbox]{\result\maxlen}{.95\ht\strutbox}}%
  \makebox[\dimexpr\maxlen-2\tabcolsep+\arrayrulewidth][r]{#2}%
}
%...