Features of Python's several techniques

Today by chance to see an article < You may not know the 30 Python language of the lifting point skills, although the python for several years, but the middle is still a lot of do not know or do not think, special here to do the next excerpt.

Original address: http://soft.chinabyte.com/database/379/12920379.shtml

1. Named slices

>>> a = [012345]>>> lastthree = Slice (-3, none)>>> lastthreeslice (-3, none, none)> >> a[lastthree][345]

2. zip packaging and Unpacking list

>>> a = [1,2,3]>>> B = ['a','b','C']>>> z =Zip (A, b)>>>z[(1,'a'), (2,'b'), (3,'C')]>>>>>> Zip (*z) [(1,2,3), ('a','b','C')]

3. Use zip to merge adjacent list items

>>> a=[1,2,3,4,5]>>> Zip (* ([ITER (a)]* 2 )) [(12), (34), (56)]
>>>
>>> Zip (A[::2], a[1::2])
[(1, 2), (3, 4), (5, 6)]

Can be written as an anonymous function

Lambda A, k:zip (* ([ITER (a)]*k))

Or

Lambda  for  in range (k)))

Where a identifies the list to be merged, and K indicates that the adjacent K elements are to be merged

>>> Group_adjacent_1 (A,3) [(1,2,3), (4,5,6)] >>> Group_adjacent_1 (A,1) [(1,), (2,), (3,), (4,), (5,), (6,)]
>>>
>>>
>>> Group_adjacent_2 (A, 3)
[(1, 2, 3), (4, 5, 6)]
>>> Group_adjacent_2 (A, 1)
[(1, 2, 3), (4, 5, 6)]

4. Creating a sliding window using zip and iterators

 from Import Islice def N_grams (A, N): ...     Z -in range (     N) ...  return Zip (*>>> a = [1, 2, 3, 4, 5, 6]>>> n_grams (A, 3) [(1, 2, 3), (2, 3, 4), (3, 4, 5), (4, 5, 6)]

Features of Python's several techniques