|NO.Z.00028|——————————|BigDataEnd|——|Hadoop&Python.v06|——|Arithmetic.v06|NumPy科学计算库：NumPy数组运算|

一、数组运算

### --- 加减乘除幂运算

import numpy as np
arr1 = np.array([1,2,3,4,5])
arr2 = np.array([2,3,1,5,9])
arr1 - arr2                                         # 减法
arr1 * arr2                                         # 乘法
arr1 / arr2                                         # 除法
arr1**arr2                                          # 两个星号表示幂运算

### --- 逻辑运算

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

### --- 数组与标量计算
### --- 数组与标量的算术运算也会将标量值传播到各个元素

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

### --- *=、+=、-=操作
### --- 某些操作（例如+=和*=）只会修改现有数组，?不是创建?个新数组。

import numpy as np
arr1 = np.arange(5)
arr1 +=5
arr1 -=5
arr1 *=5
# arr1 /=5 不?持运算

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Walter Savage Landor:strove with none,for none was worth my strife.Nature I loved and, next to Nature, Art:I warm'd both hands before the fire of life.It sinks, and I am ready to depart                                                                                                                                                    ——W.S.Landor

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