flatten是numpy.ndarray.flatten的一个函数，即返回一个一维数组。常用如下：
>>> 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 = mat(a) >>> y = a.flatten() >>> y matrix([[1, 3, 2, 4, 3, 5]]) ## 经过降维仍为矩阵类型 >>> y = a.flatten().A >>> y array([[1, 3, 2, 4, 3, 5]]) ## 此时变为数组类型 >>> shape(y) (1, 6) >>> shape(y[0]) (6,) >>> y = a.flatten().A[0] >>> y array([1, 3, 2, 4, 3, 5])
直接使用list.flatten()会出错。
>>> a = [[1,3],[2,4],["abc","def"]] >>> a.flatten() # 报错 Traceback (most recent call last): File "<pyshell#10>", line 1, in <module> a.flatten() AttributeError: 'list' object has no attribute 'flatten'
建议使用：
>>> a = [[1,3],[2,4],["abc","def"]] >>> a1 = [y for x in a for y in x] >>> a1 [1, 3, 2, 4, 'abc', 'def']
【1】https://blog.csdn.net/qq_41542989/article/details/109050472
