Text with date, how to convert?

Question

I use this script to recognise a date in a textfile and write the result in another file.

For[i = 1, i < 20, i++,
  test1 = Import["E:\\data\\MC1 Data\\MC1 Data\\articles\\" <> ToString[i] <>".txt", "Text"];
  test2 = {StringCases[test1, DatePattern[{"Year", "Month", "Day"}]],
         StringCases[ToLowerCase[test1], RegularExpression["\\w(?<!\\d)[\\w'-]*"]]};
Write[s, test2]];

The result is a file like this:

test3 = ReadList["E:\\data\\MC1 Data\\MC1 Data\\articles\\testfile3.txt"]

Then I would like to make a selection on the date/first column. In this example, mathematica don't recognise it as a datastring. I tried to convert it like

DateString[test3[[All, 1]]]

but that didnt work. Who has a suggestion?

Answer 1

In order to work with the date you should convert it to a date list. Example:

    res = {{{"2013/12/8"}, {"a", "b"}}, {{"2013/12/8"}, {"a", "b"}}};
    res2 = MapAt[DateList@First@# &, res, {All, 1}]
(* Out: {{{2013, 12, 8, 0, 0, 0.}, {"a", "b"}}, {{2013, 12, 8, 0, 0, 
   0.}, {"a", "b"}}} *)

Now you can use Select or Cases or whatever to extract data. If you just want to use DateString on each date then you could do it like this: DateString /@ res2[[All, 1]].