How typeset a numeric table from a CSV file

Question

I have a CSV file (db.txt)like this:

30.0,   0.0,    0.0
60.0,   1.9098, 5.8779
90.0,   6.9098, 9.5106
120.0,  13.09,  9.5106
150.0,  18.09,  5.8779
180.0,  20.0,   0.0

I need to typeset it. My problem is related with the wrong alignment of decimal point and the number of decimals (must be a constant for each column):

\renewcommand*{\dtlrealalign}{r}

\DTLloaddb[
    noheader,
    keys={x,y,theta},
    headers={
        \shortstack{$\boldsymbol{\theta_{2,i}}$},
        \shortstack{X},
        \shortstack{Y}
             }
  ]{db}{db.txt}
\begin{table}[t]
  \caption{Database file}
  \centering
  \DTLdisplaydb{db}
\end{table}

Any advice, please?

Answer 1

You can use pgfplotstable for this. If you load the array package, you can set the option dec sep align for pgfplotstabletypeset to get the alignment at the decimal point. Padding the numbers with zeros can be accomplished by setting fixed zerofill, the number of decimals can be set using precision, either for all columns or for individual columns by using display column/<index>/precision=<digits>.

\documentclass{article}
\usepackage{filecontents}       % For the example data
\usepackage{pgfplotstable}
\usepackage{array}      % For aligining at decimal point

\begin{filecontents}{testdata.csv}
theta, x, y
30.0,   0.0,    0.0
60.0,   1.9098, 5.8779
90.0,   6.9098, 9.5106
120.0,  13.09,  9.5106
150.0,  18.09,  5.8779
180.0,  20.0,   0.0
\end{filecontents}

\begin{document}
\pgfplotstableread[col sep=comma]{testdata.csv}{\table}

\pgfplotstabletypeset[
    dec sep align,      % Align at decimal point
    fixed zerofill,     % Fill numbers with zeros
    precision=4,        % Set number of decimals
    display columns/0/.style={precision=1}, % Change for first column (column 0)
    ] {\table}
\end{document}

---

Alternatively, you can use pgfplotstable and the siunitx package to align the columns. I've used it here in conjunction with booktabs and properly formatted column headers:

\documentclass{article}
\usepackage{pgfplotstable}
\usepackage{siunitx}
\usepackage{booktabs}

\begin{filecontents}{testdata.csv}
theta, x, y
30.0,   0.0,    0.0
60.0,   1.9098, 5.8779
90.0,   6.9098, 9.5106
120.0,  13.09,  9.5106
150.0,  18.09,  5.8779
180.0,  20.0,   0.0
\end{filecontents}

\begin{document}
\pgfplotstableread[col sep=comma]{testdata.csv}{\table}

\pgfplotstabletypeset[
    dec sep align=S,    % Use the siunitx `S` column type for aligning at decimal point
    fixed zerofill,     % Fill numbers with zeros
    precision=4,        % Set number of decimals
    display columns/0/.style={
        precision=1,    % Change for first column (column index 0)
        column name=$\theta_{2,i}$
    },
    display columns/1/.style={column name=$X$},
    display columns/2/.style={column name=$Y$},
    every head row/.style={before row=\toprule, after row=\midrule},
    every last row/.style={after row=\bottomrule},
    ] {\table}
\end{document}

Answer 2

There's no problem to do this with the datatool package and siunitx as well. Here's your example done in that way:

\documentclass{article}
\usepackage{datatool}
\usepackage{siunitx}
\usepackage{booktabs} % for nicer tables
\usepackage{caption} % improve caption spacing (among other things)
\usepackage{bm}
\renewcommand*\dtldisplaystarttab{\toprule}
\renewcommand*\dtldisplayendtab{\tabularnewline\bottomrule}
\renewcommand*\dtldisplayafterhead{\midrule}

\begin{document}
\DTLloaddb
 [
    noheader,
    keys={x,y,theta},
    headers={
    \shortstack{$\boldsymbol{\theta_{{2,i}}}$},
    \shortstack{X},
    \shortstack{Y}}
  ]
  {db}{db.txt}
\begin{table}[t]
\sisetup{
    parse-numbers   = false,
    table-number-alignment = left,
    table-figures-integer = 4,
    table-figures-decimal = 4,
    input-decimal-markers = .
    }
    \renewcommand*\dtlrealalign{S}
  \caption{Database file}
  \centering
  \DTLdisplaydb{db}
\end{table}

\end{document}