replace column values with values from different dataframe

Question

I have 2 pandas dataframes:

df1

     Home  Place
a    MS    Z2
c    KM    Z3
d    RR    R2

df2

     Place1
a    A2      
c    A66
z    F32
x    K41
t    E90

I want to replace values of df2['Place1'] with df1['Place'] when indexes are matching and leave it the same when indexes are not matching.

Desired result:

     Place1
a    Z2 
c    Z3
z    F32
x    K41
t    E90

I tried to use pd.replace but it returns NAs

BENY · Accepted Answer · 2022-11-23 15:48:53Z

1

Try with update

df2['Place1'].update(df1['Place'])
df2
Out[75]: 
  Place1
a     Z2
c     Z3
z    F32
x    K41
t    E90

answered Nov 23, 2022 at 15:48

BENY

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1 Comment

MMJJ Over a year ago

thank you for your reply. But I got this error: "Cannot set a Categorical with another, without identical categories"

steflbert · Accepted Answer · 2022-11-23 15:51:23Z

0

You can do this with update.

df2['Place1'] = df2['Place1'].update(df1['Place'])

answered Nov 23, 2022 at 15:51

steflbert

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2 Comments

MMJJ Over a year ago

thank you for your reply. But I got this error: "Cannot set a Categorical with another, without identical categories"

steflbert Over a year ago

I didn't know that you have categorical columns, then you would have to set the same categories for both first. When you turn it into a Categorical, you can specify the categories.

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