|NO.Z.00028|——————————|BigDataEnd|——|Hadoop&Python.v06|——|Arithmetic.v06|NumPy科學計算庫：NumPy數組運算|

一、數組運算

### --- 加減乘除幂運算

import numpy as np
arr1 = np.array([1,2,3,4,5])
arr2 = np.array([2,3,1,5,9])
arr1 - arr2                                         # 減法
arr1 * arr2                                         # 乘法
arr1 / arr2                                         # 除法
arr1**arr2                                          # 兩個星号表示幂運算      

### --- 邏輯運算

import numpy as np
arr1 = np.array([1,2,3,4,5])
arr2 = np.array([1,0,2,3,5])
arr1 < 5
arr1 >= 5
arr1 == 5
arr1 == arr2
arr1 > arr2      

### --- 數組與标量計算
### --- 數組與标量的算術運算也會将标量值傳播到各個元素

import numpy as np
arr = np.arange(1,10)
1/arr
arr+5
arr*5      

### --- *=、+=、-=操作
### --- 某些操作（例如+=和*=）隻會修改現有數組，⽽不是建立⼀個新數組。

import numpy as np
arr1 = np.arange(5)
arr1 +=5
arr1 -=5
arr1 *=5
# arr1 /=5 不⽀持運算      

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