Question

I am trying to extract graph information from a text file and converting it to CSV format. The data appears in the format:

    X-axis    Y-axis    dY/dX

which I intend to convert to:

X-axis,Y-axis,dY/dX

It should be noted, however, that the dY/dX column is not always present when exported from the software being used.

The regular expression I have at present is:

\s*(?<xaxis>\-*\d+\.\d+)\s*(?<yaxis>\-*\d+\.\d+)\s*(?<dydx>\-*\d+\.\d+)*

and the replacement expression is:

${xaxis},${yaxis},${dydx}

My question is this: even though the matching expression accounts for the optional nature of the dY/dX column, how can the replacement expression do the same? At present, if the dY/dX column is not present, a trailing comma is printed to the CSV file. I appreciate this is not a major problem, but I would like to know if it is possible.

Answer 1

It turns out to not be possible. I have since rewritten the program to store the data first in a DataTable instance, then generate a CSV file from that. That way, the number of columns can be determined and the necessary formatting applied to the output.