python 資料分析 Numpy(Numerical Python Basic)

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 # 匯入numpy 模組 
 1 import numpy as np 10 a = np.random.random((2,4)) 11 a 12 Out[5]:  13 array([[0.20974732, 0.73822026, 0.82760722, 0.050551  ], 14        [0.77337155, 0.06521922, 0.55524187, 0.59209907]])

 # 求矩陣所有資料的和，最小值，最大值 22 np.sum(a) 23 Out[7]: 3.812057513268513 24 np.min(a) 25 Out[8]: 0.05055099733013646 26 np.max(a) 27 Out[9]: 0.8276072194278252 28 print("a=",a) 29 a= [[0.20974732 0.73822026 0.82760722 0.050551  ] 30  [0.77337155 0.06521922 0.55524187 0.59209907]]

# axis=0 代表列， axis=1代表行

 31 print("min",np.min(a)) 32 min 0.05055099733013646
#求每列當中的最小值 33 print("lmin:",np.min(a,axis=0)) 34 lmin: [0.20974732 0.06521922 0.55524187 0.050551  ] 35 print("lmin:",np.min(a,axis=1)) 36 lmin: [0.050551   0.06521922] 37 print("sum:",np.sum(a,axis=1)) 38 sum: [1.8261258  1.98593171]

# reshape 資料， 3行4列 39 A = np.arange(2,14).reshape(3,4) 40 A 41 Out[16]:  42 array([[ 2,  3,  4,  5], 43        [ 6,  7,  8,  9], 44        [10, 11, 12, 13]])

# ndarray中最小值，最大值的序號 45 print(np.argmin(A)) 46 0 47 print(np.argmax(A)) 48 11 49 print(np.mean(A)) 50 7.5 51 print(np.average(A)) 52 7.5 53 print(A.mean()) 54 7.5
# cumsum 迭代相加 69 A 70 Out[24]:  71 array([[ 2,  3,  4,  5], 72        [ 6,  7,  8,  9], 73        [10, 11, 12, 13]]) 81 print(A.cumsum()) 82 [ 2  5  9 14 20 27 35 44 54 65 77 90] 83 A 84 Out[27]:  85 array([[ 2,  3,  4,  5], 86        [ 6,  7,  8,  9], 87        [10, 11, 12, 13]])
# clip(a, a_min, a_max) 將ndarray中的資料進行判斷，小於a_min的值都賦值為a_min, 大於a_max的都賦值a_max，在這之間的值不變。 88 print(np.clip(A,5,8)) 89 [[5 5 5 5] 90  [6 7 8 8] 91  [8 8 8 8]]
# 判斷ndarray階數，幾維向量
 99 A.ndim100 Out[30]: 2101 A102 Out[31]: 103 array([[ 2,  3,  4,  5],104        [ 6,  7,  8,  9],105        [10, 11, 12, 13]])106 A.ndim107 Out[32]: 2108 a109 Out[33]: 110 array([[0.20974732, 0.73822026, 0.82760722, 0.050551  ],111        [0.77337155, 0.06521922, 0.55524187, 0.59209907]])112 a.ndim113 Out[34]: 2114 A115 Out[35]: 116 array([[ 2,  3,  4,  5],117        [ 6,  7,  8,  9],118        [10, 11, 12, 13]])

 

python 資料分析 Numpy(Numerical Python Basic)