numpy学习笔记

一、类型设置

import numpy as np

data = [('zs', [80, 60, 75], 19),
        ('ls', [99, 97, 96], 20),
        ('ww', [98, 98, 98], 21)
        ]
# 第一种设置方式 3int32 意思是3个int32
# a = np.array(data, dtype='U2,3int32,int32')
# 第二种设置方式
a = np.array(data, dtype=
{'names': ['name', 'socre', 'age'],
 'formats': ['U2', '3int32', 'int32']})
for i in a:
    print(i['name'])

掩码操作：输出100以内3的倍数以及 3 7 公倍数

import numpy as np
a = np.arange(100)
b = [i for i in range(100) if i % 3 == 0]
c = a[a % 3 == 0]
print(b)
print(c)



#三和七的公倍数
import numpy as np

a = np.arange(100)
b = [i for i in range(100) if (i % 3 == 0 and i % 7 == 0)]
c = a[(a % 3 == 0) & (a % 7 == 0)]
print(b)
print(c)

索引排序(掩码)

import numpy as np

names = np.array(['Apple', 'Huawei', 'Mi', 'Oppo', "Vivo"])
rank = [1, 0, 3, 4, 2]
print(names[rank])