根据另一个 dataframe 中匹配的 id 替换 dataframe 列值

Question

I'm trying to replace values in a dataframe based on values in a different dataframe. Please assume there are other columns in both dataframes. A simple example:

df1

id    name  ......
123   city a
456   city b
789   city c
789   city c
456   city b
123   city a

so on and so forth

df2

id    name  ......
123   City A
456   City B
789   City C

So the resulting df should be:

id    name  ......
123   City A
456   City B
789   City C
789   City C
456   City B
123   City A

I tried out with a few merge options in pandas with no luck. Is there an easy way to replace all the values in the first dataframe with the values from the second dataframe based on a match on id ?

Any help is appreciated

Answer 1

You can do

df1['New name']=df1.id.map(df2.set_index('id').name)

Update

namediff=df1.columns.difference(df2.columns).tolist()+['id']
df3=df2.drop(df2.columns.difference(df1.columns),axis=1)
df1=df1[namediff].merge(df3,on='id')

Or

df1=df1.set_index('id')
df1.update(df2.set_index('id'))
df1.reset_index(inplace=True)