Python中flatten用法

Python中flatten用法，有需要的朋友可以参考下。

一、用在数组 

>>> a = [[1,3],[2,4],[3,5]]>>> a = array(a)>>> a.flatten()array([1, 3, 2, 4, 3, 5])

二、用在列表 

如果直接用flatten函数会出错

>>> a = [[1,3],[2,4],[3,5]]>>> a.flatten()Traceback (most recent call last):  File "<pyshell#10>", line 1, in <module>    a.flatten()AttributeError: 'list' object has no attribute 'flatten'

正确的用法

>>> a = [[1,3],[2,4],[3,5],["abc","def"]]>>> a1 = [y for x in a for y in x]>>> a1[1, 3, 2, 4, 3, 5, 'abc', 'def']

或者（不理解）

>>> a = [[1,3],[2,4],[3,5],["abc","def"]]>>> flatten = lambda x: [y for l in x for y in flatten(l)] if type(x) is list else [x]>>> flatten(a)[1, 3, 2, 4, 3, 5, 'abc', 'def']

三、用在矩阵 

>>> a = [[1,3],[2,4],[3,5]]>>> a = mat(a)>>> y = a.flatten()>>> ymatrix([[1, 3, 2, 4, 3, 5]])>>> y = a.flatten().A>>> yarray([[1, 3, 2, 4, 3, 5]])>>> shape(y)(1, 6)>>> shape(y[0])(6,)>>> y = a.flatten().A[0]>>> yarray([1, 3, 2, 4, 3, 5])

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Python中flatten用法，有需要的朋友可以参考下。