numpy数组扩展函数repeat和tile用法

numpy.repeat(a, repeats, axis=None)

>>> a = np.arange(3)
>>> a
array([0, 1, 2])
>>> np.repeat(a, 2)
array([0, 0, 1, 1, 2, 2])

>>> a = [[0,1], [2,3], [4,5]]
>>> y = np.repeat(a, 2)
>>> y
array([0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5])
>>> x = np.tile(a, (2,1))
>>> x
array([[0, 1],
       [2, 3],
       [4, 5],
       [0, 1],
       [2, 3],
       [4, 5]])

>>> a = np.array([[1,2],[3,4]])
>>> a
array([[1, 2],
       [3, 4]])
>>> np.repeat(a, 2, 1)
array([[1, 1, 2, 2],
       [3, 3, 4, 4]])

>>> np.repeat(a, 2, 0)
array([[1, 2],
       [1, 2],
       [3, 4],
       [3, 4]])

tile函数功能：对整个数组进行复制拼接

>>> a
array([[1, 2],
       [3, 4]])
>>> np.tile(a, 2)
array([[1, 2, 1, 2],
       [3, 4, 3, 4]])
#构造3*1个copy
>>> a = np.tile(a, (3, 1))
>>> a
array([[1, 2],
       [3, 4],
       [1, 2],
       [3, 4],
       [1, 2],
       [3, 4]])