|NO.Z.00032|——————————|BigDataEnd|——|Hadoop&Python.v10|——|Arithmetic.v10|NumPy科学计算库：NumPy广播机制|

一、⼴播机制

### --- ⼴播机制

~~~     当两个数组的形状并不相同的时候，我们可以通过扩展数组的⽅法来实现相加、相减、
~~~     相乘等操作，这种机制叫做⼴播（broadcasting）

### --- ⼀维数组⼴播

import numpy as np
arr1 = np.sort(np.array([0,1,2,3]*3)).reshape(4,3)          # shape(4,3)
arr2 = np.array([1,2,3])                                    # shape(3,)
arr3 = arr1 + arr2                                          # arr2进⾏⼴播复制4份 shape(4,3)
arr3

### --- ⼆维数组的⼴播

import numpy as np
arr1 = np.sort(np.array([0,1,2,3]*3)).reshape(4,3)          # shape(4,3)
arr2 = np.array([[1],[2],[3],[4]])                          # shape(4,1)
arr3 = arr1 + arr2                                          # arr2 进⾏⼴播复制3份 shape(4,3)
arr3

### --- 三维数组⼴播

import numpy as np
arr1 = np.array([0,1,2,3,4,5,6,7]*3).reshape(3,4,2)         #shape(3,4,2)
arr2 = np.array([0,1,2,3,4,5,6,7]).reshape(4,2)             #shape(4,2)
arr3 = arr1 + arr2                                          # arr2数组在0维上复制3份 shape(3,4,2)
arr3

---

 

 

 

 

 

 

 

 

 

---

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

---