First of all, as you're using matrix of nodes, you don't need to specify nodes manually. each node is only as big as it needs to be, so one (far from elegent or automatic way) is to specify minimum heights and minimum widths:
Code
\documentclass{beamer}
\usepackage{txfonts}
\usepackage{tikz}
\usetikzlibrary{matrix}
\begin{document}
\begin{frame}[fragile]{sample failure}
\begin{minipage}{\linewidth}
\begin{center}
\begin{tikzpicture}
\matrix
[ matrix of nodes,
row sep = 0.1cm,
every even row/.style = {nodes={fill=blue!50}},
every odd row/.style = {nodes={fill=red!50}},
nodes={anchor=west},
column 1/.style = {nodes={minimum width=2.8cm}},
column 2/.style = {nodes={minimum width=1.7cm}},
column 3/.style = {nodes={minimum width=4.5cm}},
row 1/.style={nodes={minimum height=1.2cm}},
row 2/.style={nodes={minimum height=1.8cm}},
row 3/.style={nodes={minimum height=1.2cm}},
row 4/.style={nodes={minimum height=0.8cm}},
]
{ blah1 & $\sum_{i=1}^n i $ & \begin{tabular}{c}line1 \\ line2 \end{tabular} \\
blah & $\sum_{i=1}^n \frac{a_i}{b_i}$ & \begin{tabular}{c}expalination 2\\ exp 3 \\ exp 4\end{tabular} \\
blah and more & $\log ^{d+4} \frac{M}{\epsilon}$ & \begin{tabular}{c}no idea\\ and more \end{tabular} \\
blah4 & $\log ^{d-1} \frac{M}{\epsilon}$ & \begin{tabular}{c}blah blah and more info\end{tabular} \\
};
\end{tikzpicture}
\end{center}
\end{minipage}
\end{frame}
\end{document}
Output
Edit 1: here's a version requiring much less tweaking: it determines heights and width automatically. You only need to manually pass the matrix name, the number of rows and colums and the colors you'd like to use to \colorfillrows. I borrowed the [on background layer] from Ignasi, thanks for that:
Code
\documentclass{beamer}
\usepackage{txfonts}
\usepackage{tikz}
\usetikzlibrary{matrix,fit,backgrounds}
\usepackage{xifthen}
\newcommand{\getdim}[1]% name of node
{ \path (#1.south west);
\pgfgetlastxy{\xsw}{\ysw}
\path (#1.north east);
\pgfgetlastxy{\xne}{\yne}
\pgfmathsetlengthmacro{\nodewidth}{\xne-\xsw}
\pgfmathsetlengthmacro{\nodeheight}{\yne-\ysw}
\xdef\widthofnode{\nodewidth}
\xdef\widthofnode{\nodeheight}
}
\newcommand{\colorfillrows}[5]% 1:matrixname, 2:numrows, 3:numcols, 4:oddcolor, 5:evencolor
{ \xdef\maxwidth{0}
\foreach \myrow in {1,...,#2}
{ \getdim{#1-\myrow-#3}
\pgfmathsetmacro{\biggerwidth}{\nodewidth>\maxwidth ? \nodewidth : \maxwidth}
\xdef\maxwidth{\biggerwidth}
}
\foreach \myrow in {1,...,#2}
{ \xdef\maxheight{0}
\xdef\myfit{}
\foreach \mycol in {1,...,#3}
{ \getdim{#1-\myrow-\mycol}
\pgfmathsetmacro{\biggerheight}{\nodeheight>\maxheight ? \nodeheight : \maxheight}
\xdef\maxheight{\biggerheight}
\xdef\myfit{\myfit(#1-\myrow-\mycol)}
}
\node[right,minimum width=\maxwidth,inner sep=0] (extra-\myrow) at (#1-\myrow-#3.west) {};
\begin{scope}[on background layer]
\pgfmathtruncatemacro{\oddrow}{mod(\myrow,2)}
\ifthenelse{\oddrow=1}{\xdef\mycolor{#4}}{\xdef\mycolor{#5}}
\node[inner sep=2pt,fit=\myfit(extra-\myrow),fill=\mycolor,inner sep=0pt] {};
\end{scope}
}
}
\begin{document}
\begin{frame}[fragile]{sample almost automatic success}
\begin{minipage}{\linewidth}
\begin{center}
\begin{tikzpicture}
\matrix (mydata)
[ matrix of nodes,
row sep = 0.1cm,
nodes={anchor=west},
]
{ blah1 & $\sum_{i=1}^n i $ & \begin{tabular}{c}line1 \\ line2 \end{tabular} \\
blah & $\sum_{i=1}^n \frac{a_i}{b_i}$ & \begin{tabular}{c}expalination 2\\ exp 3 \\ exp 4\end{tabular} \\
blah and more & $\log ^{d+4} \frac{M}{\epsilon}$ & \begin{tabular}{c}no idea\\ and more \end{tabular} \\
blah4 & $\log ^{d-1} \frac{M}{\epsilon}$ & \begin{tabular}{c}blah blah and more info\end{tabular} \\
};
\colorfillrows{mydata}{4}{3}{orange!55}{blue!30!cyan}% 1:matrixname, 2:numrows, 3:numcols, 4:oddcolor, 5:evencolor
\end{tikzpicture}
\end{center}
\end{minipage}
\end{frame}
\end{document}
Output
I am definitely unfamiliar with both beamer and tikz (do not quite get what the \only are supposed to do) but perhaps this could go in the direction you want:
\documentclass{beamer}
\usepackage{tikz}
\usetikzlibrary{chains}
\newcounter{count}
% helper macro:
\long\def\GobToSemiColon #1;{}
\newcommand\myPicture{
\begin{tikzpicture}
\begin{scope}[start chain = going below]
\ifnum\value{count}<1 \expandafter\GobToSemiColon\fi
\ifnum\value{count}>3 \expandafter\GobToSemiColon\fi
\node[draw, rectangle, on chain] {display only when counter is between
1 and 3};
\ifnum\value{count}>-1 \expandafter\GobToSemiColon\fi
\node[draw, rectangle, on chain] {display only when counter is
negative};
\ifnum\value{count}<100 \expandafter\GobToSemiColon\fi
\ifnum\value{count}>200 \expandafter\GobToSemiColon\fi
\node[draw, rectangle, on chain] {display only if counter is between
100 and 200};
\ifnum\value{count}<3 \expandafter\GobToSemiColon\fi
\ifnum\value{count}>20 \expandafter\GobToSemiColon\fi
\node[draw, circle, on chain] {only when counter is in the range 3 to 20};
\end{scope}
\end{tikzpicture}
}
\begin{document}
\begin{frame}
\only{\setcounter{count}{-3}\myPicture}
\only{\setcounter{count}{105}\myPicture}
\only{\setcounter{count}{39}\myPicture}
\only{\setcounter{count}{2}\myPicture}
\only{\setcounter{count}{5}\myPicture}
\end{frame}
\end{document}
Best Answer
You can use the
/.listfeature John Kormylo mentioned in his answer to repeat a style for different inputs.