python-numpy最全攻略二-add

4. numpy相加减

import numpy as np
 
a = np.array([[1, 2],
              [3, 4]])
 
b = np.array([[4, 3],
              [2, 1]])
               
print ("Adding 1 to every element:", a + 1)
print ("\nSubtracting 2 from each element:", b - 2)
print ("\nSum of all array "
       "elements: ", a.sum())
print ("\nArray sum:\n", a + b)

Adding 1 to every element: [[2 3]
 [4 5]]

Subtracting 2 from each element: [[ 2  1]
 [ 0 -1]]

Sum of all array elements:  10

Array sum:
 [[5 5]
 [5 5]]

5. numpy数据类型

import numpy as np
 
x = np.array([1, 2])  
print("Integer Datatype: ")
print(x.dtype)         
 
x = np.array([1.0, 2.0]) 
print("\nFloat Datatype: ")
print(x.dtype)  
 
# 规定类型
x = np.array([1, 2], dtype = np.int64)   
print("\nForcing a Datatype: ")
print(x.dtype)

Integer Datatype: 
int32

Float Datatype: 
float64

Forcing a Datatype: 
int64

6. numpy add方法

import numpy as np
 
arr1 = np.array([[4, 7], [2, 6]], 
                 dtype = np.float64)

arr2 = np.array([[3, 6], [2, 8]], 
                 dtype = np.float64) 
 
# Addition of two Arrays
Sum = np.add(arr1, arr2)
print("Addition of Two Arrays: ")
print(Sum)