Efficiently colouring block of table cells

Question

I made a table with the following code and the hhline package:

\documentclass{article}
\usepackage{hhline}
\begin{document}
\begin{tabular}{l || l l l l l | l}
& 1 & 2 & 3 & 4 & 5 & 6\\\hhline{=#=====|=}
1 & 1 & 1 & 1 & 1 & 1 & 0\\
2 & 1 & 1 & 1 & 1 & 1 & 0\\
3 & 1 & 1 & 1 & 1 & 1 & 0\\
4 & 1 & 1 & 1 & 1 & 1 & 0\\
5 & 1 & 1 & 1 & 1 & 1 & 0\\\hline
6 & 0 & 0 & 0 & 0 & 0 & 1
\end{tabular}
\end{document}

Now, I would like to colour the 5×5 block in a specific colour, and the 1×1 block in another colour. The other cells should remain as they are.

I have seen Color merged and regular cells in a table individually which suggests \cellcolor, \rowcolor and columncolor - however, in this case I could only use \cellcolor, since there are no full rows or columns. But that would mean I have to type 26 times \cellcolor. Is there no efficient way to do this (either algorithmically or by colouring a whole block at once)?

Answer 1

1. Manual Solution: You can apply \rowcolor and selectively color in white the cells which should not have color

   

2. \ColorBlock{<start row>}{<end row>}{<color>} Using collcell package we can define a macro which specifies which rows of the table to color. This applies only to columns with the L alignment defined in the MWE.

   

---

Code:

\documentclass{article}

\usepackage{hhline}
\usepackage{xcolor}
\usepackage{colortbl}

\newcommand{\RowColor}{\rowcolor{red!50} \cellcolor{white}}

\begin{document}
\begin{tabular}{l || l l l l l | l}
                  & 1 & 2 & 3 & 4 & 5 & \cellcolor{yellow}6 \\\hhline{=#=====|=}
\RowColor       1 & 1 & 1 & 1 & 1 & 1 & \cellcolor{white}0  \\
\RowColor       2 & 1 & 1 & 1 & 1 & 1 & \cellcolor{white}0  \\
\RowColor       3 & 1 & 1 & 1 & 1 & 1 & \cellcolor{white}0  \\
\RowColor       4 & 1 & 1 & 1 & 1 & 1 & \cellcolor{white}0  \\
\RowColor       5 & 1 & 1 & 1 & 1 & 1 & \cellcolor{white}0  \\\hline
\cellcolor{cyan}6 & 0 & 0 & 0 & 0 & 0 & \cellcolor{green}1
\end{tabular}
\end{document}

---

Code: \ColorBlock{<start row>}{<end row>}{<color>}

\documentclass{article}

\usepackage{hhline}
\usepackage{xcolor}
\usepackage{colortbl}

\usepackage{collcell}

\newcounter{CurrentRow}
\newcommand*{\StartRow}{1}%
\newcommand*{\EndRow}{1}%
\newcommand*{\CellColor}{white}%
\newcommand{\ColorBlock}[3]{%
    \renewcommand*{\StartRow}{#1}%
    \renewcommand*{\EndRow}{#2}%
    \renewcommand*{\CellColor}{#3}%
}

\newcommand*{\ApplyCellColor}[1]{%
    \ifnum\arabic{CurrentRow}>\numexpr\StartRow-1\relax
        \ifnum\arabic{CurrentRow}<\numexpr\EndRow+1\relax
            \cellcolor{\CellColor}#1%
        \else
            #1%
        \fi
    \else
        #1%
    \fi
}
\newcolumntype{L}{>{\collectcell\ApplyCellColor}{l}<{\endcollectcell}}%%  for left alignment
%\newcolumntype{C}{>{\collectcell\ApplyCellColor}{c}<{\endcollectcell}}%% if need center alignment
%\newcolumntype{R}{>{\collectcell\ApplyCellColor}{r}<{\endcollectcell}}%% if need right alignment

\newcommand{\RowColor}{\rowcolor{red!50} \cellcolor{white}}

\newcommand{\EndOfRow}{\stepcounter{CurrentRow}\\}% So that we know when we have ended a row
\newenvironment{MyTabular}[1]{%
    \setcounter{CurrentRow}{1}%
    \begin{tabular}{#1}%
}{%
    \end{tabular}%
    \gdef\CellColor{white}%
}


\begin{document}
\ColorBlock{2}{6}{red} 
\begin{MyTabular}{l || L L L L L | l}
       & 1 & 2 & 3 & 4 & 5 & 6 \EndOfRow\hhline{=#=====|=}
     1 & 1 & 1 & 1 & 1 & 1 & 0 \EndOfRow
     2 & 1 & 1 & 1 & 1 & 1 & 0 \EndOfRow
     3 & 1 & 1 & 1 & 1 & 1 & 0 \EndOfRow
     4 & 1 & 1 & 1 & 1 & 1 & 0 \EndOfRow
     5 & 1 & 1 & 1 & 1 & 1 & 0 \EndOfRow\hline
     6 & 0 & 0 & 0 & 0 & 0 & 1
\end{MyTabular}\verb|\ColorBlock{2}{6}{red}:|

\medskip
\ColorBlock{3}{5}{cyan} 
\begin{MyTabular}{l || L L L L L | l}
       & 1 & 2 & 3 & 4 & 5 & 6 \EndOfRow\hhline{=#=====|=}
     1 & 1 & 1 & 1 & 1 & 1 & 0 \EndOfRow
     2 & 1 & 1 & 1 & 1 & 1 & 0 \EndOfRow
     3 & 1 & 1 & 1 & 1 & 1 & 0 \EndOfRow
     4 & 1 & 1 & 1 & 1 & 1 & 0 \EndOfRow
     5 & 1 & 1 & 1 & 1 & 1 & 0 \EndOfRow\hline
     6 & 0 & 0 & 0 & 0 & 0 & 1
\end{MyTabular}\verb|\ColorBlock{3}{5}{cyan}:|

\end{document}

Answer 2

If you color the cells, you need no rule. And you never need vertical rules in tables (nor double rules).

\documentclass{article}
\usepackage{xcolor}
\usepackage{colortbl}

\begin{document}
\begin{tabular}{l *{5}{>{\columncolor{blue!20}}l} l}
\rowcolor{white}%
& 1 & 2 & 3 & 4 & 5 & 6\\
1 & 1 & 1 & 1 & 1 & 1 & 0\\
2 & 1 & 1 & 1 & 1 & 1 & 0\\
3 & 1 & 1 & 1 & 1 & 1 & 0\\
4 & 1 & 1 & 1 & 1 & 1 & 0\\
5 & 1 & 1 & 1 & 1 & 1 & 0\\
\rowcolor{white}%
6 & 0 & 0 & 0 & 0 & 0 & \cellcolor{green!20}1
\end{tabular}
\end{document}

Note that \rowcolor takes precedence over \columncolor and \cellcolor overrides both.

Answer 3

In {NiceTabular} of nicematrix, you have commands in the \CodeBefore to color the cells, rectangles, rows or columns you want.

You won't have the thin white lines you see in some PDF viewers at some levels of zoom.

\documentclass{article}
\usepackage{xcolor}
\usepackage{nicematrix}
\begin{document}
\begin{NiceTabular}{lllllll}
\CodeBefore
  \rectanglecolor{blue!20}{2-2}{6-6}
  \cellcolor{green!20}{7-7}
\Body
  & 1 & 2 & 3 & 4 & 5 & 6\
1 & 1 & 1 & 1 & 1 & 1 & 0\
2 & 1 & 1 & 1 & 1 & 1 & 0\
3 & 1 & 1 & 1 & 1 & 1 & 0\
4 & 1 & 1 & 1 & 1 & 1 & 0\
5 & 1 & 1 & 1 & 1 & 1 & 0\
6 & 0 & 0 & 0 & 0 & 0 & 1\
\end{NiceTabular}
\end{document}

You need several compilations (because nicematrix uses PGF/Tikz nodes under the hood).