Python numpy生成矩阵、串联矩阵代码分享

import numpy

生成numpy矩阵的几个相关函数:

numpy.array()

numpy.zeros()

numpy.ones()

numpy.eye()

串联生成numpy矩阵的几个相关函数:

numpy.array()

numpy.row_stack()

numpy.column_stack()

numpy.reshape()

>>> import numpy

>>> numpy.eye(3)

array([[ 1., 0., 0.],

[ 0., 1., 0.],

[ 0., 0., 1.]])

>>> numpy.zeros(3)

array([ 0., 0., 0.])

>>> numpy.ones(3)

array([ 1., 1., 1.])

>>> x1 = numpy.array((1, 2, 3))

>>> x1

array([1, 2, 3])

>>> x2 = numpy.array([4, 5, 6])

>>> x2

array([4, 5, 6])

>>> x3 = numpy.array((x1, x2))

>>> x3

array([[1, 2, 3],

[4, 5, 6]])

>>> x4 = x3.reshape(2, 3)

>>> x4

array([[1, 2, 3],

[4, 5, 6]])

>>> x4 = x3.reshape(3, 2)

>>> x4

array([[1, 2],

[3, 4],

[5, 6]])

>>> x5 = numpy.row_stack(x1, x2)

Traceback (most recent call last):

File "<stdin>", line 1, in <module>

TypeError: vstack() takes exactly 1 argument (2 given)

>>> x5 = numpy.row_stack((x1, x2))

>>> x5

array([[1, 2, 3],

[4, 5, 6]])

>>> x6 = numpy.row_stack([x1, x2])

>>> x6

array([[1, 2, 3],

[4, 5, 6]])

>>> x7 = numpy.row_stack((x6, x2))

>>> x7

array([[1, 2, 3],

[4, 5, 6],

[4, 5, 6]])

>>> x7[0]

array([1, 2, 3])

>>> x7[1]

array([4, 5, 6])

>>> x7[2]

array([4, 5, 6])

>>> x8 = numpy.column_stack([x1, x2, x1, x2])

>>> x8

array([[1, 4, 1, 4],

[2, 5, 2, 5],

[3, 6, 3, 6]])

>>> x8[0]

array([1, 4, 1, 4])

>>> x8[1]

array([2, 5, 2, 5])

>>> x8[2]

array([3, 6, 3, 6])

>>> x8[3]

Traceback (most recent call last):

File "<stdin>", line 1, in <module>

IndexError: index 3 is out of bounds for axis 0 with size 3

>>> x8[0][3]

4

>>>

python生成1行四列全2矩阵

print np.ones((1,4))*2

总结

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