[Python知识库]边代码边学习03

1. join( )

Python join() 方法用于将序列中的元素以指定的字符连接生成一个新的字符串。

s1 = "-"
s2 = ""
seq = ("r", "u", "n", "o", "o", "b") # 字符串序列
print (s1.join( seq ))
print (s2.join( seq ))

以上实例输出结果如下：

r-u-n-o-o-b
runoob

2. pandas.apply()

import numpy as np
import pandas as pd
 
 
f = lambda x: x.max()-x.min()
 
df = pd.DataFrame(np.random.randn(4,3),columns=list('bde'),index=['utah', 'ohio', 'texas', 'oregon'])
print(df)
 
t1 = df.apply(f)
print(t1)
 
t2 = df.apply(f, axis=1)
print(t2)

以上实例输出结果如下：

               b         d         e
utah    1.106486  0.101113 -0.494279
ohio    0.955676 -1.889499  0.522151
texas   1.891144 -0.670588  0.106530
oregon -0.062372  0.991231  0.294464
 
b    1.953516
d    2.880730
e    1.016430
dtype: float64
 
utah      1.600766
ohio      2.845175
texas     2.561732
oregon    1.053603
dtype: float64