I basically have this
first
0 bar
1 bar
2 foo
3 foo
bar foo
0 a b
I want to insert value in dataframe 2 to dataframe 1, so the final result should be something like this
first
0 a
1 a
2 b
3 b
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2 Answers
You can simply use replace like so:
>>> df1.replace(df2.transpose()[0])
first
0 a
1 a
2 b
3 b
If you want to check efficiency:
%timeit df1.replace(df2.transpose()[0])
711 µs ± 18.7 µs per loop (mean ± std. dev. of 7 runs, 1000 loops each)
1 Comment
Andreas
good answer, you propably could shorten it like this:
df1.replace(df2.T)[0])You can use join on a transposed df2:
df1.set_index('first').join(df2.T)
Out[11]:
0
bar a
bar a
foo b
foo b
Or with a dictionary:
df1['first'].map(df2.T.to_dict()[0])
Out[17]:
0 a
1 a
2 b
3 b
Name: first, dtype: object
Or with merge:
df1.merge(df2.T.reset_index(), left_on=['first'], right_on=['index'])
first index 0
0 bar bar a
1 bar bar a
2 foo foo b
3 foo foo b
