Pandas Brain Teasers/

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Merge the Values of Two DataFrames

Merge the Values of Two DataFrames

Understand how to merge the Pandas DataFrames.

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Try it yourself

Try executing the code below to see the result.

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import pandas as pd
df1 = pd.DataFrame({
  'id': [1, 2, 3],
  'name': ['Clark Kent', 'Diana Prince', 'Bruce Wayne'],
})
df2 = pd.DataFrame({
  'id': [2, 1, 4],
  'hero': ['Wonder Woman', 'Superman', 'Aquaman'],
})
df = pd.merge(df1, df2, on='id')
print(df)

Explanation

A pandas merge gets a sequence of pandas.DataFrame to merge plus an optional column to merge on. If the column is not provided, pandas will use the index of each DataFrame for merging.

The question is, what happens when one merge column has values that the other doesn’t? This old question is rooted in relational databases and their join operator. There are several types of joins, and each defines a different behavior. The pandas merge function mimics these operators as well. Looking at ...