Pandas — Joining

Basic join

import pandas as pd

df1 = pd.DataFrame({'A': [1, 2, 3]}, index=['a', 'b', 'c'])
df2 = pd.DataFrame({'B': [4, 5, 6]}, index=['a', 'b', 'd'])

# Inner join
result = df1.join(df2, how='inner')

# Left join
result = df1.join(df2, how='left')

# Right join
result = df1.join(df2, how='right')

# Outer join
result = df1.join(df2, how='outer')

Join vs Merge

# Join uses index
df1.join(df2)

# Merge uses columns
pd.merge(df1, df2, left_index=True, right_index=True)

Mini Practice

1. Join on index
2. Use different join types
3. Compare join and merge
4. Handle missing values

Up Next

Continue with Concat - Concatenating DataFrames.