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读书笔记 numpy入门第2章数组拼接

admin 11月 14, 2020 0

np.concatenate


x = np.array([1, 2, 3])
y = np.array([3, 2, 1])
np.concatenate([x, y])

array([1, 2, 3, 3, 2, 1])

# 拼接3个数组
z = [99, 99, 99]
print(np.concatenate([x, y, z]))

[ 1  2  3  3  2  1 99 99 99]

二维数组拼接

grid = np.array([[1, 2, 3],
                 [4, 5, 6]])

# 沿着第一个轴拼接
np.concatenate([grid, grid])

array([[1, 2, 3],
                [4, 5, 6],
                [1, 2, 3],
                [4, 5, 6]])

# 沿着第二个轴拼接（从0开始索引）
np.concatenate([grid, grid], axis=1)

array([[1, 2, 3, 1, 2, 3],
           [4, 5, 6, 4, 5, 6]])

https://docs.scipy.org/doc/numpy/reference/generated/numpy.concatenate.html

np.vstack

x = np.array([1, 2, 3])
grid = np.array([[9, 8, 7],
                 [6, 5, 4]])

# 垂直栈数组
np.vstack([x, grid])

array([[1, 2, 3],
           [9, 8, 7],
           [6, 5, 4]])

https://docs.scipy.org/doc/numpy/reference/generated/numpy.vstack.html

np.hstack

# 水平栈数组
y = np.array([[99],
              [99]])
np.hstack([grid, y])

>>> array([[ 9,  8,  7, 99],
           [ 6,  5,  4, 99]])

https://docs.scipy.org/doc/numpy/reference/generated/numpy.hstack.html

np.dstack

https://www.numpy.org/devdocs/reference/generated/numpy.dstack.html

沿着第三个维度拼接数组

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