Problems aligning on a decimal in a table with colored rows

Question

I'm having a problem with making a "pretty" table

The intent is to have alternating light background colors with black text for normal rows to facilitate reading across, with the header having a blue background and white text to make it stand out, and having numbers line up on the decimal, with "nominal" columns being separated by vertical lines

I think these are the relevant lines of LaTeX code

\usepackage{color,colortbl}

\renewcommand{arrayrulewidth}{1.5}

\definecolor{headercolor}{rgb}{0.392,0.584,0.929}
\definecolor{oddrowcolor}{rgb}{0.961,1.000,0.980}
\definecolor{evenrowcolor}{rgb}{0.902,0.902,0.980}
\definecolor{white}{rgb}{1.0,1.0,1.0}

\begin{table}{!htbp}
\large
\begin{caption}
\begin{tabular}{|r@{.}l|r@{.}l|}
\hline
\multicolumn{2}{|c|}{\cellcolor{headercolor}{\color{white}{column 1 header}}} & \multicolumn{2}{|c|}{\cellcolor{headercolor}{\color{white}{column 2 header}}} \\
\hline
\rowcolor{oddrowcolor}
-0&333 & 1&444 \\
\rowcolor{evenrowcolor}
1&001 &  10.02 \\
\rowcolor{oddrowcolor}
0& & 401&32 \\
\hline
\end{tabular}
\end{center}
\caption{\label{table:example} Some caption.}
\end{table}

The problems I have are

1. \rowcolor isn't playing nice with the align on decimal stuff (splitting the "nominal" column at the decimal and doing r@{.}l for the alignment of "actual" columns making up a "nominal" column) basically the left half of the smallest digit in the left (with alignment r) actual column and the decimal point are being hidden
2. the vertical lines are showing up double thick in the header (twice as thick as in the normal rows)

I greatly appreciate if anyone can help me with this.

By the way, I'm compiling with a version of pdflatex that shipped with redhat 5.X (not sure what X is and I can't upgrade the machine's LaTeX because I'm not an administrator and it has to be compiled on this machine).

Answer 1

This seems like the perfect application for the siunitx package's S column type, which I have used below as

    \begin{tabular}{|S[table-format=1.0]S[table-format=3.0]S[table-format=3.2]S[table-format=3.0]|}

The S type takes an optional argument in which you can specify formatting options; I have used

table-format=<number of integers before decimal>-<number of integers after decimal>

MWE

\documentclass{article}
\usepackage{siunitx}
\usepackage{colortbl}
\definecolor{headercolor}{rgb}{0.392,0.584,0.929}
\definecolor{oddrowcolor}{rgb}{0.961,1.000,0.980}
\definecolor{evenrowcolor}{rgb}{0.902,0.902,0.980}
\definecolor{white}{rgb}{1.0,1.0,1.0}

\begin{document}

\begin{table}[!htbp]
    \centering
    \caption{SIunitx}
    \label{table:example} 
    \begin{tabular}{|S[table-format=1.0,parse-numbers=false]|S[table-format=3.0,parse-numbers=false]|S[table-format=3.2]|S[table-format=3.0]|}
        \hline
        \multicolumn{2}{|c|}{\cellcolor{headercolor}{\color{white}{column 1 header}}} & \multicolumn{2}{c|}{\cellcolor{headercolor}{\color{white}{column 2 header}}} \\
        \hline
        \rowcolor{oddrowcolor}
        -0 & 333 & 1     & 444 \\
        \rowcolor{evenrowcolor}
        1  & 001 & 10.02 &     \\
        \rowcolor{oddrowcolor}
        0  &     & 401   & 32  \\
        \hline
    \end{tabular}
\end{table}

\end{document}

Some other notes:

• The reason for the 'double thickness' was because you specified the vertical line twice, once in each \multicolumn; remove one of them (as I have done above) and you'll see the thickness just as 'single'
• I've used \centering which is preferable to center as discussed in Should I use center or centering for figures and tables?
• I put the caption above the table as discussed in Why should a table caption be placed above the table?
• a lot of folks would recommend not using vertical lines; see the booktabs documentation for examples.

If you don't have access to the siunitx package, then you can achieve a similar result using the dcolumn package, as shown below

\documentclass{article}
\usepackage{dcolumn}
\usepackage{colortbl}
\definecolor{headercolor}{rgb}{0.392,0.584,0.929}
\definecolor{oddrowcolor}{rgb}{0.961,1.000,0.980}
\definecolor{evenrowcolor}{rgb}{0.902,0.902,0.980}
\definecolor{white}{rgb}{1.0,1.0,1.0}

\newcolumntype{d}[1]{D{.}{.}{#1}}


\begin{document}

\begin{table}[!htbp]
    \centering
    \caption{dcolumn}
    \label{table:example} 
    \begin{tabular}{|d{0}|d{0}|d{2}|d{0}|}
        \hline
        \multicolumn{2}{|c|}{\cellcolor{headercolor}{\color{white}{column 1 header}}} & \multicolumn{2}{c|}{\cellcolor{headercolor}{\color{white}{column 2 header}}} \\
        \hline
        \rowcolor{oddrowcolor}
        -0 & 333 & 1     & 444 \\
        \rowcolor{evenrowcolor}
        1  & 001 & 10.02 &     \\
        \rowcolor{oddrowcolor}
        0  &     & 401   & 32  \\
        \hline
    \end{tabular}
\end{table}
\end{document}

Answer 2

cmhughes' answer remains valid, but I guess you wanted an output like this (although you missed one . in your code where an & should have been).

---

I also added an example (at the beginng) that uses xcolor's \rowcolors command to get alternating row colors, so you don't have to apply them manually (what would you have done if you had twenty rows?).

It has three obligatory parameters:

• the first line that gets the odd-row color,
• the odd-row color, and
• the even-row color.

\rowcolors{1}{evenrowcolor}{oddrowcolor}

The first row's color will be overwritten by its own \rowcolor command.

---

Loosely related to you question I added examples of tables that

• don't use lines and colors
  • only colors
  • only horizontal lines provided by the booktabs package (which produce in my eyes a cleaner/prettier output, but your mileage may vary)
• highlights the uses of the table-format options by siunitx.

Code

\documentclass{article}
\usepackage{siunitx}
\usepackage[table]{xcolor}
\definecolor{headercolor}{rgb}{0.392,0.584,0.929}
\definecolor{oddrowcolor}{rgb}{0.961,1.000,0.980}
\definecolor{evenrowcolor}{rgb}{0.902,0.902,0.980}
\definecolor{white}{rgb}{1.0,1.0,1.0}
\usepackage{booktabs}
\begin{document}
\centering % for this example

{%
\rowcolors{1}{evenrowcolor}{oddrowcolor}%
\begin{tabular}{S[table-format=+1.2]S[table-format=3.3]}
    \rowcolor{headercolor}{\color{white}{column 1 header}} & {\color{white}{column 2 header}} \\
    -0.333                                                 & 1.444                            \\
    1.001                                                  & 10.02                            \\
    0                                                      & 401.32                           \\
\end{tabular}%
}

\vspace{2.4em} % for this example
\begin{tabular}{S[table-format=+1.2]S[table-format=3.3]}
    \rowcolor{headercolor}{\color{white}{column 1 header}} & {\color{white}{column 2 header}} \\
    \rowcolor{oddrowcolor} -0.333                          & 1.444                            \\
    \rowcolor{evenrowcolor} 1.001                          & 10.02                            \\
    \rowcolor{oddrowcolor}  0                              & 401.32                           \\
\end{tabular}

\vspace{2.4em} % for this example
\begin{tabular}{|S[table-format=+1.2]|S[table-format=3.3]|}
    \hline
    \rowcolor{headercolor}{\color{white}{column 1 header}} & {\color{white}{column 2 header}} \\ \hline
    \rowcolor{oddrowcolor} -0.333                          & 1.444                            \\
    \rowcolor{evenrowcolor} 1.001                          & 10.02                            \\
    \rowcolor{oddrowcolor}  0                              & 401.32                           \\ \hline
\end{tabular}

\vspace{2.4em} % for this example
\begin{tabular}{S[table-format=+1.2]S[table-format=3.3]}
    \toprule
    {column 1 header} & {column 2 header} \\ \midrule
    -0.333            & 1.444             \\
    1.001             & 10.02             \\
    0                 & 401.32            \\ \bottomrule
\end{tabular}

\vspace{2.4em} % for this example
\begin{tabular}{
    S
    S[table-format = 2.2]
    S[table-format = 2.2(1)]
    S[table-format = +2.2]
    S[table-format = 2.2e1]
}
    \toprule
    {Values} & {Values} & {Values} & {Values} &  \\ \midrule
    2.3      & 2.3      & 2.3(5)   & 2.3      & 2.3e8   \\
    34.23    & 34.23    & 34.23(4) & 34.23    & 34.23   \\
    56.78    & 56.78    & 56.78(3) & -56.78   & 56.78e3 \\
    3,76     & 3,76     & 3.76(2)  & +-3.76   & e6      \\ \bottomrule
\end{tabular}
\end{document}

Output

Answer 3

Thanks so much for all your help, Qrrbrbirlbel was right about aligning on the decimal. The machine I need to do this on does not have siunitx installed on it so this is the solution I'm going with (I didn't know of dcolumn so thanks for that a quick google search turned up a pdf document that mentioned using D{.}{.}{-1} would center it on the decimal rather than right justify it with N decimal places.

\documentclass{article}
\usepackage{dcolumn}
\usepackage[table]{xcolor}
\definecolor{headercolor}{rgb}{0.392,0.584,0.929}
\definecolor{oddrowcolor}{rgb}{0.961,1.000,0.980}
\definecolor{evenrowcolor}{rgb}{0.902,0.902,0.980}
\definecolor{white}{rgb}{1.0,1.0,1.0}
\newcolumntype{d}{D{.}{.}{-1}}
\begin{document}

{
\rowcolors{1}{evenrowcolor}{oddrowcolor}
\begin{tabular}{|d|d}
\multicolumn{1}{|c|}{\cellcolor{headercolor}\color{white}{column 1 header}} & \multicolumn{1}{c|}{\cellcolor{headercolor}\color{white}{column 2 header}} \\
-0.333                                                 & 1.444 \\
1.001                                                  & 10.02 \\
0                                                      & 401.32 \\
\end{tabular}
}
\end{document}