【原】【Colab系列】Colab中的numpy模塊

融水公子 2020-04-05

展開全文

講解對象：【Colab系列】Colab中的numpy模塊
作者：融水公子 rsgz
文章出處：360doc個人圖書館[其他平臺均為盜版]
提醒：建議大家電腦瀏覽我的網(wǎng)頁，因為手機瀏覽網(wǎng)頁代碼會自動縮成一行，很不方便

1 首先我們進入colab
2 先導入這個模塊

import numpy as np

我們快捷鍵Ctrl+enter運行代碼是沒有任何反應的因為只是導入模塊并沒有要求輸出什么對象，所以說很正常

3 如果你不放心覺得這可能是一個報錯或者說colab里面沒有預先安裝numpy模塊那么我換換一個numpy1導入試試看

分析：里面是報錯的恰恰證明了 numpy模塊其實 colab已經(jīng)準備好了直接拿來使用就行了如果我們在windows cmd中還需要使用下面的命令下載這個模塊才能使用

pip install numpy

4 下面要講解的內(nèi)容之前我先簡介一下 numpy的一個子模塊以及他的作用

numpy.linalg.eigvals(a)：計算矩陣的特征值
numpy.random.rand(d0, d1, ..., dn)：定一個數(shù)組，并使用 [0, 1) 區(qū)間隨機數(shù)據(jù)填充，這些數(shù)據(jù)均勻分布
%timeit：行魔術(shù) 作用就是計算代碼運行時間

5 好了既然了解上上面的基礎(chǔ)知識我們開始運行代碼試試

import numpy as np

%timeit np.linalg.eigvals(np.random.rand(100,100))
--------------------------
運行結(jié)果：100 loops, best of 3: 9.15 ms per loop

6 大家可能還是不理解這一連串代碼的含義，那么我分別分開執(zhí)行代碼你們就理解了

import numpy as np

np.random.rand(100,100)
-------------------------------------------
array([[0.16350277, 0.37400986, 0.10178194, ..., 0.32097701, 0.1236406 ,
        0.69012982],
       [0.67244973, 0.80989966, 0.69928216, ..., 0.08353696, 0.79816447,
        0.43216955],
       [0.04322875, 0.91927785, 0.96039567, ..., 0.18260893, 0.65009984,
        0.49157518],
       ...,
       [0.96179641, 0.15853575, 0.47757648, ..., 0.31463299, 0.92844948,
        0.22672775],
       [0.84039929, 0.44765895, 0.18632183, ..., 0.42013944, 0.63246891,
        0.19807404],
       [0.95109206, 0.28346964, 0.79318681, ..., 0.3488978 , 0.72919665,
        0.52356033]])

計算矩陣特征值

import numpy as np

np.linalg.eigvals(np.random.rand(100,100))
----------------------------------------------
array([ 4.98688515e+01+0.j        ,  2.94358500e+00+0.39372138j,
        2.94358500e+00-0.39372138j,  2.35359342e+00+1.66540043j,
        2.35359342e+00-1.66540043j, -2.08735822e+00+2.02297922j,
       -2.08735822e+00-2.02297922j,  2.61822599e+00+0.48100139j,
        2.61822599e+00-0.48100139j,  2.52007100e+00+0.82237737j,
        2.52007100e+00-0.82237737j,  2.18774082e+00+1.5428337j ,
        2.18774082e+00-1.5428337j , -2.86232242e+00+0.j        ,
        1.29284401e+00+2.40761747j,  1.29284401e+00-2.40761747j,
       -2.62728724e-01+2.74054182j, -2.62728724e-01-2.74054182j,
        3.90579355e-01+2.64091009j,  3.90579355e-01-2.64091009j,
       -2.63565758e+00+0.10544969j, -2.63565758e+00-0.10544969j,
       -1.92677751e+00+1.80026535j, -1.92677751e+00-1.80026535j,
       -1.20257141e+00+2.26796126j, -1.20257141e+00-2.26796126j,
        8.57605035e-01+2.34251948j,  8.57605035e-01-2.34251948j,
       -2.32258644e+00+0.73203228j, -2.32258644e+00-0.73203228j,
        1.24517400e+00+2.10278497j,  1.24517400e+00-2.10278497j,
       -6.58807923e-01+2.37933184j, -6.58807923e-01-2.37933184j,
       -1.90068618e+00+1.28159438j, -1.90068618e+00-1.28159438j,
       -3.94619768e-01+2.28014446j, -3.94619768e-01-2.28014446j,
        1.47024478e+00+1.65197049j,  1.47024478e+00-1.65197049j,
       -9.75808102e-01+2.01345677j, -9.75808102e-01-2.01345677j,
        3.60730899e-02+2.20199655j,  3.60730899e-02-2.20199655j,
       -1.30087924e+00+1.58701533j, -1.30087924e+00-1.58701533j,
       -1.96926219e+00+0.33887089j, -1.96926219e+00-0.33887089j,
        1.67697895e+00+1.06938718j,  1.67697895e+00-1.06938718j,
       -1.53689480e+00+1.03937219j, -1.53689480e+00-1.03937219j,
       -1.84884558e+00+0.j        ,  1.77648815e+00+0.59702772j,
        1.77648815e+00-0.59702772j, -1.61232897e+00+0.76028212j,
       -1.61232897e+00-0.76028212j,  4.35460936e-01+1.72786858j,
        4.35460936e-01-1.72786858j,  1.59237786e+00+0.j        ,
        9.01864182e-01+1.44284542j,  9.01864182e-01-1.44284542j,
       -8.79438533e-01+1.50520595j, -8.79438533e-01-1.50520595j,
        1.46895682e+00+0.68125497j,  1.46895682e+00-0.68125497j,
       -6.39873806e-01+1.62912958j, -6.39873806e-01-1.62912958j,
       -1.65966584e+00+0.11489318j, -1.65966584e+00-0.11489318j,
        1.36418785e+00+0.j        ,  1.08037042e+00+0.97289752j,
        1.08037042e+00-0.97289752j,  1.87854535e-01+1.53337093j,
        1.87854535e-01-1.53337093j,  1.17840609e+00+0.j        ,
       -1.32999101e-01+1.41908441j, -1.32999101e-01-1.41908441j,
       -2.56589953e-01+1.34938522j, -2.56589953e-01-1.34938522j,
        6.40772344e-01+1.04624058j,  6.40772344e-01-1.04624058j,
        4.26505612e-01+1.08850977j,  4.26505612e-01-1.08850977j,
       -9.33501429e-01+0.8121111j , -9.33501429e-01-0.8121111j ,
       -2.26618289e-01+0.86841114j, -2.26618289e-01-0.86841114j,
        6.38558850e-01+0.39603606j,  6.38558850e-01-0.39603606j,
        2.81993337e-01+0.24234895j,  2.81993337e-01-0.24234895j,
        5.77502304e-01+0.49656662j,  5.77502304e-01-0.49656662j,
       -5.88368540e-01+0.22915341j, -5.88368540e-01-0.22915341j,
       -4.54324260e-01+0.49207133j, -4.54324260e-01-0.49207133j,
       -6.10408376e-01+0.05428372j, -6.10408376e-01-0.05428372j])

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