Split a (possibly very large) CSV file into a file for each column, using Julia

csvsplit.jl

# https://stackoverflow.com/questions/632475/regex-to-pick-commas-outside-of-quotes
comma = r"(,)(?=(?:[^\"]|\"[^\"]*\")*$)"

open(datafile) do csv 
    header = split(readline(csv),comma)
    numCols = length(header)
    outs=[open("$f.txt","w") for f in header]
    while !eof(csv)
        vals = split(readline(csv), comma)
        foreach(zip(outs,vals)) do outval
            (out,val) = outval
            write(out, val) + write(out, '\n')
        end
    end
    map(close, outs)
end