count()，列表推导式，transpose()

Posted 2020-11-10 离云1

count()函数 列表推导式

In [85]:

#统计列表每个元素中指定单词出现的个数

words=[‘apple‘,‘pare‘,‘banana‘,‘and‘,‘peach‘,‘Anda‘]

for word in words:

    print(word.lower().count(‘a‘))  #lower()识别大小写

1
1
3
1
1
2

In [86]:

 [word for word in words if word.lower().count(‘a‘)>=2]

 

 

Out[86]:

[‘banana‘, ‘Anda‘]

In [69]:

strings=[‘a‘,‘bv‘,‘tit‘,‘apple‘,‘ctr‘]

[x.title() for x in strings if len(x)>2]

 

 

Out[69]:

[‘Tit‘, ‘Apple‘, ‘Ctr‘]

In [74]:

list(map(len,strings))

  

Out[74]:

[1, 2, 3, 5, 3]

 

transpose() 转置

In [88]:

import numpy as np

three=np.arange(18).reshape(2,3,3)

 

In [89]:

three

 

Out[89]:

array([[[ 0,  1,  2],
        [ 3,  4,  5],
        [ 6,  7,  8]],

       [[ 9, 10, 11],
        [12, 13, 14],
        [15, 16, 17]]])

In [97]:

 

three.transpose(2,1,0)

Out[97]:

array([[[ 0,  9],
        [ 3, 12],
        [ 6, 15]],

       [[ 1, 10],
        [ 4, 13],
        [ 7, 16]],

       [[ 2, 11],
        [ 5, 14],
        [ 8, 17]]])