如何交换不同列表和不同大小的熊猫中的元素？

Question

我有一个数据框df1。数据框有一个名为“路径”的列。每行都有一个列表。他们是这样的：

Path                   
____________________
[OAK, PHX, MIA, FLL, PBG]   
[OAK, SEA, FLL, PBG]   
[OAK, LAS, ORD, FLL, PBG]   
[OAK, DFW, FLL, PBG]
...

我希望将每个奇数行的second和third值与下一行（偶数行）的相应second和third值交换，然后交换每对分别。在上面的输入示例中，应该将第一行的值PHX, MIA与第二行的值SEA, FLL交换，然后取反。

Path                   
____________________
[OAK, PHX, MIA, FLL, PBG]   
[OAK, SEA, FLL, PBG]   

# Swap 2nd and 3rd value between rows 

Path                   
____________________
[OAK, SEA, FLL, FLL, PBG]   
[OAK, PHX, MIA, PBG]

# Swap 2nd and 3rd value in all rows
Path                   
____________________
[OAK, FLL, SEA, FLL, PBG]   
[OAK, MIA, PHX, PBG]

结果应该是这样的：

Path                   
____________________
[OAK, FLL, SEA, FLL, PBG]   
[OAK, MIA, PHX, PBG]   
[OAK, FLL, DFW, FLL, PBG]   
[OAK, ORD, LAS, PBG]
.... 

如何使用Python？

Answer 1

out = df['Path'].apply(lambda x : pd.Series(x)  )

dfLength = len(df)
if dfLength%2==0:
    oddIndex = list(range(0,dfLength-1, 2))
    evenIndex = list(range(1, dfLength,2))
else:
    oddIndex = list(range(0,dfLength, 2))
    evenIndex = list(range(1, dfLength,2))

#Swapping odd-even rows
oddData = out.iloc[oddIndex][[1,2]].copy() 
evenData = out.iloc[evenIndex][[1,2]].copy()

out.iloc[oddIndex, [1,2]] = evenData.values
out.iloc[evenIndex, [1,2]] = oddData.values

#Swapping columns 2 & 3
col2 = out.loc[:,1].copy()
col3 = out.loc[:,2].copy()

out.loc[:,1] = col3.values
out.loc[:,2] = col2.values

最终输出看起来像

     0    1    2    3    4
0  OAK  FLL  SEA  FLL  PBG
1  OAK  MIA  PHX  PBG  NaN
2  OAK  FLL  DFW  FLL  PBG
3  OAK  ORD  LAS  PBG  NaN

如果您希望将输出作为列表，

out.apply(lambda x : list(x.dropna().values), axis = 1)

0    [OAK, PHX, MIA, FLL, PBG]
1         [OAK, SEA, FLL, PBG]
2    [OAK, LAS, ORD, FLL, PBG]
3         [OAK, DFW, FLL, PBG]
4         [OAK, DFW, FLL, PBG]