Recently I found the very useful siunitx package, and immediately looked to use it for some tables. Unfortunately, I already have all my numbers typeset with , thousand separator and . decimal separator.
If I try something like:
\documentclass{standalone}
\usepackage[group-separator={,}]{siunitx}
\begin{document}
\begin{tabular}{S[table-format=6.2]}
300,000.12\\
\end{tabular}
\end{document}
I get errors like:
Duplicate decimal marker '.' in input.
If I replace 300,000.12 with 300,000 it considers it as the 300.000 (i.e., 300).
This seems strange to me as the package interprets 300000 as 300,000 but it interprets 300,000 as 300.000.
I've scanned through the detailed siunitx documentation, but could not find any flags for picking up input separators. Anyone know how siunitx can be parameterised to treat raw input numbers like 300,000.12 gracefully?
(I would rather not remove all commas from all input numbers.)

group-separator={,}keeps the comma in the output. Thanks! (I think this should be default behaviour for the package: to consider comma as a thousands separator in the input to keep consistent with the output.) – badroit Apr 11 '12 at 18:32siunitxpackage parses your input, then typesets it according to the current settings. The standard settings use a thin space as a group separator as this is recommended by a number of authorities. – Joseph Wright Apr 11 '12 at 18:40