Groupby for key,value-csv-files

groupby.fish

function groupby
  for o in (cut -d ',' -f 1 $argv[1] | uniq)
    echo -n "{\"$o\":["
    grep "$o" $argv[1] | cut -d ',' -f 2 | sed 's/^\(.*\)$/"\1"/' | tr '\n' ','| sed 's/,$//'
    echo "]}"
  end
end