numpy模块

import numpy as np  #矩阵计算包
In [2]:
#1创建数组
np.array([1,3,5])
Out[2]:
array([1, 3, 5])
In [5]:
np.array([[1,3,5],[2,7,9]])
Out[5]:
array([[1, 3, 5],
       [2, 7, 9]])
In [6]:
a=np.array([[1,3,5],[2,7,9]])
type(a)
 Out[6]:
numpy.ndarray
In [7]:
a.shape#显示有多少行多少列
Out[7]:
(2, 3)
In [8]:
#自动填充
np.arange(1,10,2)#开始 结束 步长
Out[8]:
array([1, 3, 5, 7, 9])
In [37]:
np.linspace(0,10,100)#开始  结束  生成多少个
Out[37]:
array([ 0.        ,  0.1010101 ,  0.2020202 ,  0.3030303 ,  0.4040404 ,
        0.50505051,  0.60606061,  0.70707071,  0.80808081,  0.90909091,
        1.01010101,  1.11111111,  1.21212121,  1.31313131,  1.41414141,
        1.51515152,  1.61616162,  1.71717172,  1.81818182,  1.91919192,
        2.02020202,  2.12121212,  2.22222222,  2.32323232,  2.42424242,
        2.52525253,  2.62626263,  2.72727273,  2.82828283,  2.92929293,
        3.03030303,  3.13131313,  3.23232323,  3.33333333,  3.43434343,
        3.53535354,  3.63636364,  3.73737374,  3.83838384,  3.93939394,
        4.04040404,  4.14141414,  4.24242424,  4.34343434,  4.44444444,
        4.54545455,  4.64646465,  4.74747475,  4.84848485,  4.94949495,
        5.05050505,  5.15151515,  5.25252525,  5.35353535,  5.45454545,
        5.55555556,  5.65656566,  5.75757576,  5.85858586,  5.95959596,
        6.06060606,  6.16161616,  6.26262626,  6.36363636,  6.46464646,
        6.56565657,  6.66666667,  6.76767677,  6.86868687,  6.96969697,
        7.07070707,  7.17171717,  7.27272727,  7.37373737,  7.47474747,
        7.57575758,  7.67676768,  7.77777778,  7.87878788,  7.97979798,
        8.08080808,  8.18181818,  8.28282828,  8.38383838,  8.48484848,
        8.58585859,  8.68686869,  8.78787879,  8.88888889,  8.98989899,
        9.09090909,  9.19191919,  9.29292929,  9.39393939,  9.49494949,
        9.5959596 ,  9.6969697 ,  9.7979798 ,  9.8989899 , 10.        ])
In [13]:
a=np.linspace(0,10,100)
a.reshape((20,5))#变形 20行 5 列

Out[13]:

array([[ 0.        ,  0.1010101 ,  0.2020202 ,  0.3030303 ,  0.4040404 ],
       [ 0.50505051,  0.60606061,  0.70707071,  0.80808081,  0.90909091],
       [ 1.01010101,  1.11111111,  1.21212121,  1.31313131,  1.41414141],
       [ 1.51515152,  1.61616162,  1.71717172,  1.81818182,  1.91919192],
       [ 2.02020202,  2.12121212,  2.22222222,  2.32323232,  2.42424242],
       [ 2.52525253,  2.62626263,  2.72727273,  2.82828283,  2.92929293],
       [ 3.03030303,  3.13131313,  3.23232323,  3.33333333,  3.43434343],
       [ 3.53535354,  3.63636364,  3.73737374,  3.83838384,  3.93939394],
       [ 4.04040404,  4.14141414,  4.24242424,  4.34343434,  4.44444444],
       [ 4.54545455,  4.64646465,  4.74747475,  4.84848485,  4.94949495],
       [ 5.05050505,  5.15151515,  5.25252525,  5.35353535,  5.45454545],
       [ 5.55555556,  5.65656566,  5.75757576,  5.85858586,  5.95959596],
       [ 6.06060606,  6.16161616,  6.26262626,  6.36363636,  6.46464646],
       [ 6.56565657,  6.66666667,  6.76767677,  6.86868687,  6.96969697],
       [ 7.07070707,  7.17171717,  7.27272727,  7.37373737,  7.47474747],
       [ 7.57575758,  7.67676768,  7.77777778,  7.87878788,  7.97979798],
       [ 8.08080808,  8.18181818,  8.28282828,  8.38383838,  8.48484848],
       [ 8.58585859,  8.68686869,  8.78787879,  8.88888889,  8.98989899],
       [ 9.09090909,  9.19191919,  9.29292929,  9.39393939,  9.49494949],
       [ 9.5959596 ,  9.6969697 ,  9.7979798 ,  9.8989899 , 10.        ]])
In [16]:
a.resize((20,5))#改变了值本身形态 -
a
Out[16]:
array([[ 0.        ,  0.1010101 ,  0.2020202 ,  0.3030303 ,  0.4040404 ],
       [ 0.50505051,  0.60606061,  0.70707071,  0.80808081,  0.90909091],
       [ 1.01010101,  1.11111111,  1.21212121,  1.31313131,  1.41414141],
       [ 1.51515152,  1.61616162,  1.71717172,  1.81818182,  1.91919192],
       [ 2.02020202,  2.12121212,  2.22222222,  2.32323232,  2.42424242],
       [ 2.52525253,  2.62626263,  2.72727273,  2.82828283,  2.92929293],
       [ 3.03030303,  3.13131313,  3.23232323,  3.33333333,  3.43434343],
       [ 3.53535354,  3.63636364,  3.73737374,  3.83838384,  3.93939394],
       [ 4.04040404,  4.14141414,  4.24242424,  4.34343434,  4.44444444],
       [ 4.54545455,  4.64646465,  4.74747475,  4.84848485,  4.94949495],
       [ 5.05050505,  5.15151515,  5.25252525,  5.35353535,  5.45454545],
       [ 5.55555556,  5.65656566,  5.75757576,  5.85858586,  5.95959596],
       [ 6.06060606,  6.16161616,  6.26262626,  6.36363636,  6.46464646],
       [ 6.56565657,  6.66666667,  6.76767677,  6.86868687,  6.96969697],
       [ 7.07070707,  7.17171717,  7.27272727,  7.37373737,  7.47474747],
       [ 7.57575758,  7.67676768,  7.77777778,  7.87878788,  7.97979798],
       [ 8.08080808,  8.18181818,  8.28282828,  8.38383838,  8.48484848],
       [ 8.58585859,  8.68686869,  8.78787879,  8.88888889,  8.98989899],
       [ 9.09090909,  9.19191919,  9.29292929,  9.39393939,  9.49494949],
       [ 9.5959596 ,  9.6969697 ,  9.7979798 ,  9.8989899 , 10.        ]])
In [18]:
a.flatten()#对数组降维，数组本身不变
Out[18]:
array([ 0.        ,  0.1010101 ,  0.2020202 ,  0.3030303 ,  0.4040404 ,
        0.50505051,  0.60606061,  0.70707071,  0.80808081,  0.90909091,
        1.01010101,  1.11111111,  1.21212121,  1.31313131,  1.41414141,
        1.51515152,  1.61616162,  1.71717172,  1.81818182,  1.91919192,
        2.02020202,  2.12121212,  2.22222222,  2.32323232,  2.42424242,
        2.52525253,  2.62626263,  2.72727273,  2.82828283,  2.92929293,
        3.03030303,  3.13131313,  3.23232323,  3.33333333,  3.43434343,
        3.53535354,  3.63636364,  3.73737374,  3.83838384,  3.93939394,
        4.04040404,  4.14141414,  4.24242424,  4.34343434,  4.44444444,
        4.54545455,  4.64646465,  4.74747475,  4.84848485,  4.94949495,
        5.05050505,  5.15151515,  5.25252525,  5.35353535,  5.45454545,
        5.55555556,  5.65656566,  5.75757576,  5.85858586,  5.95959596,
        6.06060606,  6.16161616,  6.26262626,  6.36363636,  6.46464646,
        6.56565657,  6.66666667,  6.76767677,  6.86868687,  6.96969697,
        7.07070707,  7.17171717,  7.27272727,  7.37373737,  7.47474747,
        7.57575758,  7.67676768,  7.77777778,  7.87878788,  7.97979798,
        8.08080808,  8.18181818,  8.28282828,  8.38383838,  8.48484848,
        8.58585859,  8.68686869,  8.78787879,  8.88888889,  8.98989899,
        9.09090909,  9.19191919,  9.29292929,  9.39393939,  9.49494949,
        9.5959596 ,  9.6969697 ,  9.7979798 ,  9.8989899 , 10.        ])
In [20]:
a.ravel()#对数组降维并改变了数组
Out[20]:
array([ 0.        ,  0.1010101 ,  0.2020202 ,  0.3030303 ,  0.4040404 ,
        0.50505051,  0.60606061,  0.70707071,  0.80808081,  0.90909091,
        1.01010101,  1.11111111,  1.21212121,  1.31313131,  1.41414141,
        1.51515152,  1.61616162,  1.71717172,  1.81818182,  1.91919192,
        2.02020202,  2.12121212,  2.22222222,  2.32323232,  2.42424242,
        2.52525253,  2.62626263,  2.72727273,  2.82828283,  2.92929293,
        3.03030303,  3.13131313,  3.23232323,  3.33333333,  3.43434343,
        3.53535354,  3.63636364,  3.73737374,  3.83838384,  3.93939394,
        4.04040404,  4.14141414,  4.24242424,  4.34343434,  4.44444444,
        4.54545455,  4.64646465,  4.74747475,  4.84848485,  4.94949495,
        5.05050505,  5.15151515,  5.25252525,  5.35353535,  5.45454545,
        5.55555556,  5.65656566,  5.75757576,  5.85858586,  5.95959596,
        6.06060606,  6.16161616,  6.26262626,  6.36363636,  6.46464646,
        6.56565657,  6.66666667,  6.76767677,  6.86868687,  6.96969697,
        7.07070707,  7.17171717,  7.27272727,  7.37373737,  7.47474747,
        7.57575758,  7.67676768,  7.77777778,  7.87878788,  7.97979798,
        8.08080808,  8.18181818,  8.28282828,  8.38383838,  8.48484848,
        8.58585859,  8.68686869,  8.78787879,  8.88888889,  8.98989899,
        9.09090909,  9.19191919,  9.29292929,  9.39393939,  9.49494949,
        9.5959596 ,  9.6969697 ,  9.7979798 ,  9.8989899 , 10.        ])
In [23]:
##创建多维数组并自动填充
np.ones((2,5))#2行5列 用1填充
Out[23]:
array([[1., 1., 1., 1., 1.],
       [1., 1., 1., 1., 1.]])
In [24]:
np.zeros((2,5))#用0填充
Out[24]:
array([[0., 0., 0., 0., 0.],
       [0., 0., 0., 0., 0.]])
In [29]:
np.empty((2,5))#随机数填充

Out[29]:

array([[0., 0., 0., 0., 0.],
       [0., 0., 0., 0., 0.]])
In [33]:
np.eye(3)#3*3矩阵
Out[33]:
array([[1., 0., 0.],
       [0., 1., 0.],
       [0., 0., 1.]])
In [35]:
a=np.eye(3)
np.diag(a,1)#对角线矩阵
Out[35]:
array([0., 0.])
In [36]:
np.full((3,3),8)#全部为8的三乘以3矩阵
Out[36]:
array([[8, 8, 8],
       [8, 8, 8],
       [8, 8, 8]])
In [38]:
np.random.rand(2,5)#o-1 之间均匀分布

Out[38]:

array([[0.63777893, 0.61140518, 0.31321926, 0.99111662, 0.77213003],
       [0.66032703, 0.26635147, 0.51230109, 0.00825155, 0.80438856]])
In [39]:
np.random.randn(2,5)#标准正太分布
Out[39]:
array([[-0.85813291, -0.51808816,  0.84557228,  0.25999279, -0.26334869],
       [ 0.80162927,  0.52697261, -0.55807018,  1.15921478, -1.75240519]])
In [41]:
np.random.seed(0)#随机数种子
np.random.rand(2,5)

Out[41]:

array([[0.5488135 , 0.71518937, 0.60276338, 0.54488318, 0.4236548 ],
       [0.64589411, 0.43758721, 0.891773  , 0.96366276, 0.38344152]])
In [65]:
a=np.arange(10).reshape(5,2)
 In [66]:
np.random.shuffle(a)#对一个序列进行随机排序
Out[66]:
array([[6, 7],
       [2, 3],
       [8, 9],
       [4, 5],
       [0, 1]])
In [67]:
##切割与组合
a=[1,2,3]
b=[4,5,6]
np.hstack((a,b))#横向组合
Out[67]:
array([1, 2, 3, 4, 5, 6])
In [68]:
np.vstack((a,b))#纵向组合
Out[68]:
array([[1, 2, 3],
       [4, 5, 6]])
In [71]:
import numpy.linalg as nl#矩阵计算包
In [72]:
a=np.full((3,3),8)
a
Out[72]:
array([[8, 8, 8],
       [8, 8, 8],
       [8, 8, 8]])
In [73]:
nl.det(a)#计算行列式
Out[73]:
0.0
In [74]:
nl.eig(a)#计算特征值与特征向量
Out[74]:
(array([-1.77635684e-15,  2.40000000e+01,  0.00000000e+00]),
 array([[-0.81649658,  0.57735027,  0.        ],
        [ 0.40824829,  0.57735027, -0.70710678],
        [ 0.40824829,  0.57735027,  0.70710678]]))
In [76]:
nl.qr(a)#计算qr分解
Out[76]:
(array([[-0.57735027, -0.57735027, -0.57735027],
        [-0.57735027,  0.78867513, -0.21132487],
        [-0.57735027, -0.21132487,  0.78867513]]),
 array([[-13.85640646, -13.85640646, -13.85640646],
        [  0.        ,   0.        ,   0.        ],
        [  0.        ,   0.        ,   0.        ]]))
In [77]:
nl.svd(a)#计算奇异值分解
Out[77]:
(array([[-0.57735027, -0.57735027, -0.57735027],
        [-0.57735027, -0.21132487,  0.78867513],
        [-0.57735027,  0.78867513, -0.21132487]]),
 array([24.,  0.,  0.]),
 array([[-0.57735027, -0.57735027, -0.57735027],
        [ 0.        , -0.70710678,  0.70710678],
        [ 0.81649658, -0.40824829, -0.40824829]]))
 
 
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原文地址：https://www.cnblogs.com/Koi504330/p/11908887.html