Tabularx alignment error

Question

I have a question with respect to the tabularx environment and the addition of new columns. Currently I have the code for a 2-column table as

[![enter image description here][1]][1]

However when I try to add additional columns, such as using the following code, I seem to get an error. The code is as follows, for example:

 \documentclass{article}
            \usepackage{tabularx}
            \usepackage{booktabs}
            \newcolumntype{L}{ >{\RaggedRight}X }
            \usepackage{siunitx}
            \noindent
            \newcolumntype{Y}{ >{\Centering}X}
            \begin{tabularx}{\textwidth}{@{} l L S[table-format=1.4] @{}}
        \toprule  

        Category  & &  {Market Index} & &   {Barclay's Event Driven} 
        & &    {Hedge Fund Index} \\   
        \midrule   
        Momentum & & 0 & & 0 & & 0  \\ \addlinespace

        Size    & & 0 & & 0 & & 0  \\ \addlinespace

        Value   & & 0 & & 0 & & 0 \\ \addlinespace

        Market Index & & 0.498 & & 0 & & 0 \\ \addlinespace

        \bottomrule
    \end{tabularx}
\enddocument

But I end up getting an error that says "extra alignment tab has been changed to \cr". Could someone please advise me with respect to this ? If anyone else has any additional formatting tips for me, I would greatly appreciate it. Thank you.

Answer 1

Not sure what you want, but you declared a table with 3 columns and used 6 &, which correspond to 7 columns, as though you thought a pair of & are equired to separate columns. I can assure you 1 is enough :o). So I added one column to the declaration and here is the code and result. Fot the column heads, I suggest loading makecell, which allows for line breaks inside \thead cells and a common formatting. I would also delete the last addlinespace(unless specific requirements, as bootabs already adds some vertical paddin above \bottomrule:

\documentclass{article}
\usepackage{tabularx}
\usepackage{booktabs, ragged2e, makecell}
\renewcommand\theadfont{\normalfont\bfseries}
\newcolumntype{L}{ >{\RaggedRight}X }
\usepackage{siunitx}
\setlength\parindent{0pt}
\newcolumntype{Y}{ >{\Centering}X}

\begin{document}

\begin{tabularx}{\textwidth}{@{} lYY S[table-format=1.4] @{}}
  \toprule
  \thead[lc]{Category }& \thead{Market Index} & {\thead{Barclay's \\Event Driven}}
  & {\thead{Hedge Fund \\Index}} \\
  \midrule
  Momentum & 0 & 0 & 0 \\ 
  \addlinespace
  Size & 0 & 0 & 0 \\ 
  \addlinespace
  Value & 0 & 0 & 0 \\ 
  \addlinespace
  Market Index & 0.498 & 0 & 0 \\ 
  \bottomrule
\end{tabularx}

\end{document}