shuffle the lines of a large file

François Pinard pinard at
Mon Mar 7 20:34:50 CET 2005

[Joerg Schuster]

> I am looking for a method to "shuffle" the lines of a large file.

If speed and space are not a concern, I would be tempted to presume that
this can be organised without too much difficulty.  However, looking for
speed handling a big file, while keeping equiprobability of all possible
permutations, might be sensibly more difficult.

I vaguely remember having read something along these lines (not
shuffling as you mean it, but still, reorganising a lengthy file) in
Knuth's "Art of Computer Programming", in one of the exercises within
the chapter on Sorting methods (volume 3).  That's long ago, but if I
remember well, Knuth did not consider this as an easy exercise.

François Pinard

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