TikZ matrix, style for combination or rows and columns

Question

In the TikZ manual we have the example below that shows how to apply an style to an entry of the matrix. It is also easy to apply it for an entire row and an entire column. My question is how can we achieve the same for several entries? Is there a simple way to specify a style, say for example, rows 1 & 3 and columns 1 & 2?

\documentclass{beamer}
\usepackage{tikz}
\usetikzlibrary{matrix}
\begin{document}
\begin{tikzpicture}[row 2 column 3/.style=red]
\matrix [matrix of nodes]
{
 8 & 1 & 6 \\
 3 & 5 & 7 \\
 4 & 9 & 2 \\
  };
 \end{tikzpicture}
 \end{document}

Answer 1

You can use the /.list feature John Kormylo mentioned in his answer to repeat a style for different inputs.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{matrix}
\begin{document}
\tikzset{myset/.style={row 2 column #1/.style={nodes={text=red}}}}
\begin{tikzpicture}[myset/.list={1,3,5}]
\matrix [matrix of nodes]
{
 8 & 1 & 6 & 8 & 1 & 6 \\
 3 & 5 & 7 & 3 & 5 & 7 \\
 4 & 9 & 2 & 4 & 9 & 2 \\
  };
\end{tikzpicture}
\end{document}

Answer 2

More a long comment than a real answer... Based on percusse's answer, this style allows to specify both row and column.

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{matrix}
\begin{document}
\tikzset{myset/.style args = {(#1,#2)}{%
    row #1 column #2/.style={nodes={text=red}}}}
\begin{tikzpicture}[myset/.list={(2,1),(3,3),(1,5)}]
\matrix [matrix of nodes]
{
 8 & 1 & 6 & 8 & 1 & 6 \\
 3 & 5 & 7 & 3 & 5 & 7 \\
 4 & 9 & 2 & 4 & 9 & 2 \\
  };
\end{tikzpicture}
\end{document}

Answer 3

This can be done via \foreach indeed, but since the keys set with \pgfkeys are not global, their assignment are lost when the loop is exited. Unless you mess with \globaldef, as in the following example:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{matrix}
\begin{document}

\newcommand{\rows}[2]{% #1 = rows, #2 = style
\foreach \r in {#1} {%
  \globaldefs=1\relax
  \tikzset{row \r/.style={#2}}
}%
}

\newcommand{\cols}[2]{% #1 = columns, #2 = style
\foreach \r in {#1} {%
  \globaldefs=1\relax
  \tikzset{column \r/.style={#2}}
}%
}

\begin{tikzpicture}
\cols{1,3}{blue}
\rows{1,3}{red}
\matrix [matrix of nodes]
{
 8 & 1 & 6 \\
 3 & 5 & 7 \\
 4 & 9 & 2 \\
  };
 \end{tikzpicture}
\end{document}

Answer 4

Interestingly, you cannot do this using \foreach. I understand this is because \foreach is actually implemented using \pgfkeys using the /.list={...} feature, but I'm a bit fuzzy on the details.

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{matrix}

\newcommand{\row}[2]{% #1 = row, #2 = style
\tikzset{row #1/.style={#2}}}

\newcommand{\col}[2]{% #1 = column, #2 = style
\tikzset{column #1/.style={#2}}}

\begin{document}
\begin{tikzpicture}
\row{1}{red}
\row{3}{red}
\col{1}{blue}
\col{3}{blue}
\matrix [matrix of nodes]
{
 8 & 1 & 6 \\
 3 & 5 & 7 \\
 4 & 9 & 2 \\
  };
 \end{tikzpicture}
 \end{document}

Answer 5

I reopen this old questions because, from percusse's and cjorssen's answers, I managed to assign style to a block of cells only specifying its (top,left to bottom,right) coordinates. I share here my solution, hoping it will help someone else.

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{matrix}
\begin{document}
\tikzset{myblocks/.style args = {(#1,#2 to #3,#4)}{
            blockrows/.style={
                block/.style={
                    row ##1 column ####1/.style={nodes={text=red}}
                },
                block/.list={#2,...,#4}
            },
            blockrows/.list={#1,...,#3}
        }
}
\begin{tikzpicture}[myblocks/.list={(1,1 to 2,2),(1,4 to 3,5)}]
\matrix [matrix of nodes]
{
 8 & 1 & 6 & 8 & 1 & 6 \\
 3 & 5 & 7 & 3 & 5 & 7 \\
 4 & 9 & 2 & 4 & 9 & 2 \\
  };
\end{tikzpicture}
\end{document}