CODEWITHSUNDEEP
pythonpandasdataframeinversion
ldoe
ldoe

Reputation: 340

Pandas find duplicates with reversed values between columns

What is the fastest way to find duplicates where value from Column A have been reversed with value from Column B?

For example, if I have a DataFrame with :

     Column A           Column B
0           C                  P
1           D                  C
2           L                  G
3           A                  D
4           B                  P
5           B                  G
6           P                  B
7           J                  T
8           P                  C
9           J                  T

The result will be :

     Column A           Column B
0           C                  P
8           P                  C
4           B                  P
6           P                  B

I tried :

df1 = df
df2 = df
for i in df2.index:
     res = df1[(df1['Column A'] == df2['Column A'][i]) & (df1['Column B'] == df2['Column B'][i])]

But this is very slow and it iterates over the same values...

Upvotes: 3

Views: 1039

Answers (2)

jezrael
jezrael

Reputation: 863226

Use merge with renamed columns DataFrame:

d = {'Column A':'Column B','Column B':'Column A'}
df = df.merge(df.rename(columns=d))
print (df)
  Column A Column B
0        C        P
1        B        P
2        P        B
3        P        C

Upvotes: 5

Sumanth
Sumanth

Reputation: 507

You could try using reindex for inversion.

column_Names=["B","A"]
df=df.reindex(columns=column_Names)

Or you could just do this:

col_list = list(df)   # get a list of the columns
col_list[0], col_list[1] = col_list[1], col_list[0]
df.columns = col_list   # assign back

Upvotes: 0

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