Python Pandas Update Conditional on DF2 Column Values

Question

I have 2 dataframes:

df1

       hair    eyes   gender  

joe     br      bl      m
mary    bl      br      f
pete    rd      gr      m

and I want to update df1 with values from df2 IF subject to some values in some additional columns

       hair    eyes   gender  weight  height

joe     bk      gr      m       150     72
mary    bl      br      f       125     55
pete    rd      gr      m       180     68

I want to do this:

df1.update(df2)   #if df2 height is over 70

but not sure how or if it's possible to specify condition.

The output I'd get after the operation is:

       hair    eyes   gender  

joe     bk      gr      m
mary    bl      br      f
pete    rd      gr      m

So only Joe was updated because his height was over 70.

Is there some way to conditionally specify update or is it best to just make another df where df2['height'] > 70?

Thanks in advance

jpp · Accepted Answer · 2018-12-14 17:47:05Z

2

Just filter df2 before you update:

df1.update(df2[df2['height'] > 70])

answered Dec 14, 2018 at 17:47

jpp

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2 Comments

Windstorm1981 Over a year ago

I read the documentation and it wasn't clear that I could do that. But I guess I can! Thanks.

jpp Over a year ago

@Windstorm1981, No problem. Consider accepting the answer (and this previous one if it helped).

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