CODEWITHSUNDEEP
pythonpython-2.7pandasdataframe
sato
sato

Reputation: 862

Creating new pandas dataframe by extracting columns from other dataframes - ValueError

I have to extract columns from different pandas dataframes and merge them into a single new dataframe. This is what I am doing:

newdf=pd.DataFrame()
newdf['col1']=sorted(df1.columndf1.unique())
newdf['col2']=df2.columndf2.unique(),
newdf['col3']=df3.columndf3.unique()
newdf

I am sure that the three columns have the same length (I have checked) but I get the error

ValueError: Length of values does not match length of index

I have tried to pass them as pd.Series but the result is the same. I am on Python 2.7.

Upvotes: 0

Views: 1384

Answers (1)

jezrael
jezrael

Reputation: 862441

It seems there is problem length of unique values is different.

One possible solution is concat all data together and apply unique.
If unique data not same sizes, get NaNs in last values of columns.

newdf = pd.concat([df1.columndf1, df2.columndf2, df3.columndf3], axis=1)
          .apply(lambda x: pd.Series(x.unique()))

EDIT:

Another possible solution:

a = sorted(df1.columndf1.unique())
b = list(df2.columndf2.unique())
c = list(df3.columndf3.unique())

newdf=pd.DataFrame({'col1':a, 'col2':b, 'col3':c})

Upvotes: 2

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