ValueError: Columns must be same length as key: python replacing DF1's column with DF2

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I have two dataframes. One dataframe one first, dataframe two second.

I want to replace country value based on DF 2.

Code Country Column C Column D
100 NULL foo mei
200 NULL bar tes
100 NULL foo1 mei1
200 NULL bar1 tes1
100 NULL foo2 mei2
200 NULL bar2 tes2
Code Country
100 Canada
200 USA

Tried:

df1['Country'] = df2.replace(df1['Code'],df1['Country']

But this is throwing error: Columns must be same length as key

Code Country Column C Column D
100 Canada foo mei
200 USA bar tes
100 Canada foo1 mei1
200 USA bar1 tes1
100 Canada foo2 mei2
200 USA bar2 tes2
pandas python replace
1 Answers

I would not use the replace method but a join.

import pandas as pd

code = [100, 200, 100, 200]
df1 =  pd.DataFrame(code, columns=['code'])
df1["country"] = None

df1.head()

# return
code    country
100     None
200     None
100     None
200     None


code2 = [100, 200]
coutry2 = ["Canada", "USA"]
df2 = pd.DataFrame(list(zip(code2, coutry2)), columns=['code', 'country'])
df2.head()
# output
code    country
100     Canada
200     USA


resutls = pd.merge(df1, df2, on='code', how='left')
resutls.head()

# output
 code   country_x   country_y
100     None        Canada
200     None        USA
100     None        Canada
200     None        USA

results_clean = resutls[['code', 'country_y']]
results_clean.columns = ['code', 'country']
results_clean.head()

code    country
100     Canada
200     USA
100     Canada
200     USA
user_38442700
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