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| -rw-r--r-- | Doc/howto/pyporting.rst | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/Doc/howto/pyporting.rst b/Doc/howto/pyporting.rst index 309f3f7..df0d299 100644 --- a/Doc/howto/pyporting.rst +++ b/Doc/howto/pyporting.rst @@ -505,6 +505,18 @@ Otherwise it might very well be worth your time and effort to port your tests to :mod:`unittest`. +Update `map` for imbalanced input sequences +''''''''''''''''''''''''''''''''''''''''''' + +With Python 2, `map` would pad input sequences of unequal length with +`None` values, returning a sequence as long as the longest input sequence. + +With Python 3, if the input sequences to `map` are of unequal length, `map` +will stop at the termination of the shortest of the sequences. For full +compatibility with `map` from Python 2.x, also wrap the sequences in +:func:`itertools.zip_longest`, e.g. ``map(func, *sequences)`` becomes +``list(map(func, itertools.zip_longest(*sequences)))``. + Eliminate ``-3`` Warnings ------------------------- |