Merging multiple dataframe columns into one using for loop

Question

Below is the script that I am using

dfs = [df2,df3,df4,df5,df6]
for i in dfs:
    df_merge = pd.merge(df1,i,how='left',on='Date')
print("Shape of df_merge = ",df_merge.shape)

Let us assume the shape of each individual dataframes is (100,2). 'Date' is the common column in all. After using above script and printing I am getting a shape of (100,3) i.e only df6 is getting merged with df1. I need to merge all in one. Any suggestion will be appreciated?

Benoit Drogou · Accepted Answer · 2021-08-03 10:12:56Z

1

It is because you save every thing in df_merge. df_merge is always the latest merged, not the sum of all merged dataframes.

I would suggest to set df_merge to a value first, like this.

dfs = [df2,df3,df4,df5,df6]
df_merge = df1
for i in dfs:
    df_merge = pd.merge(df_merge,i,how='left',on='Date')
print("Shape of df_merge = ",df_merge.shape)

answered Aug 3, 2021 at 10:12

Benoit Drogou

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