Python中flatten用法
2017-05-08 16:50
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一、用在数组
[python] view plain copy print?>>> a = [[1,3],[2,4],[3,5]] >>> a = array(a) >>> a.flatten() array([1, 3, 2, 4, 3, 5])
>>> 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[python] view plain copy print?
>>> 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’
>>> 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
[python] view plain copy print?
>>> 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’]
>>> 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)
[python] view plain copy print?
>>> 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’]
>>> 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
[python] view plain copy print?>>> a = [[1,3],[2,4],[3,5]] >>> a = mat(a) >>> y = a.flatten() >>> y matrix([[1, 3, 2, 4, 3, 5]]) >>> y = a.flatten().A >>> y array([[1, 3, 2, 4, 3, 5]]) >>> shape(y) (1, 6) >>> shape(y[0]) (6,) >>> y = a.flatten().A[0] >>> y array([1, 3, 2, 4, 3, 5])
>>> a = [[1,3],[2,4],[3,5]] >>> a = mat(a) >>> y = a.flatten() >>> y matrix([[1, 3, 2, 4, 3, 5]]) >>> y = a.flatten().A >>> y array([[1, 3, 2, 4, 3, 5]]) >>> shape(y) (1, 6) >>> shape(y[0]) (6,) >>> y = a.flatten().A[0] >>> y array([1, 3, 2, 4, 3, 5])
转自博客:http://blog.csdn.net/maoersong/article/details/23823925
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