How to update the empty dataframe values with values from another dataframe(Pandas)?

Question

I want to update empty rows in dataframe1 with the equivalent values from dataframe2 only if the rows in dataframe1 is empty.

Cases:

fig 1

fig 2

In the above example, I want to fill only empty rows of Price columns in dataframe1 with the equivalent Price columns from dataframe2.

Any ideas or suggestions for this?

import pandas as pd

df1 = pd.read_csv('dataframe1.csv')
df2 = pd.read_csv('dataframe2.csv')

rhug123 · Accepted Answer · 2021-01-05 19:31:02Z

2

Try this:

 df2dict = df2.set_index(['Product Code'])['Price'].squeeze().to_dict()
 # maps from df2['Product Code'] to empty columns in df
 df['Price'] = df['Price'].fillna(df['Product Code'].map(df2dict))

edited Jan 5, 2021 at 19:31

answered Jan 4, 2021 at 16:26

rhug123

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1 Comment

rhug123 Over a year ago

I see that this post was edited, but shouldnt it be df['Product Code'].map(df2dict)? This will return a series that matches df1, but will only fill in the nan values.

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