基于pandas中expand的作用详解
expand表示是否把series类型转化为DataFrame类型
下面代码中的ｎ表示去掉下划线"_"的数量
代码如下：
import numpy as np
import pandas as pd
s2 = pd.Series(['a_b_c_f_j', 'c_d_e_f_h', np.nan, 'f_g_h_x_g'])
print("-----------------------------------")
print(s2.str.split('_'))
print("-----------------------------------")
print(s2.str.split('_').str.get(1))
print("-----------------------------------")
print(s2.str.split('_').str[1])
print("---------------expand=True--------------------")
expand1=s2.str.split('_', expand=True)
print(expand1)
print(type(expand1))
print("---------------expand=False--------------------")
expand2=s2.str.split('_', expand=False)
print(expand2)
print(type(expand２))
print("##########################################################")
print("---------------expand=True,n=1--------------------")
expand1=s2.str.rsplit('_', expand=True,n=1)
print(expand1)
print("---------------expand=False,n=1--------------------")
expand2=s2.str.rsplit('_', expand=False,n=1)
print(expand2)
运行结果如下：
-----------------------------------
0 [a, b, c, f, j]
1 [c, d, e, f, h]
2 NaN
3 [f, g, h, x, g]
dtype: object
-----------------------------------
0 b
1 d
2 NaN
3 g
dtype: object
-----------------------------------
0 b
1 d
2 NaN
3 g
dtype: object
---------------expand=True--------------------
0 1 2 3 4
0 a b c f j
1 c d e f h
2 NaN NaN NaN NaN NaN
3 f g h x g
<class 'pandas.core.frame.DataFrame'>
---------------expand=False--------------------
0 [a, b, c, f, j]
1 [c, d, e, f, h]
2 NaN
3 [f, g, h, x, g]
dtype: object
<class 'pandas.core.series.Series'>
##########################################################
---------------expand=True,n=1--------------------
0 1
0 a_b_c_f j
1 c_d_e_f h
2 NaN NaN
3 f_g_h_x g
---------------expand=False,n=1--------------------
0 [a_b_c_f, j]
1 [c_d_e_f, h]
2 NaN
3 [f_g_h_x, g]
dtype: object
[Finished in 0.4s]
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