Pandas DataFrame merge is the process of combining two DataFrames into a single DataFrame based on a common column or columns. This can be useful for combining data from different sources or for performing data analysis on multiple data sets.
Using the merge() method
The merge() method takes two DataFrames as input and returns a new DataFrame that is the merged result of the two input DataFrames. The merge() method can be used to perform a variety of merge types, including inner joins, outer joins, left joins, and right joins.
Here is an example of how to use the merge() method to merge two DataFrames:
import pandas as pd
df1 = pd.DataFrame({'name': ['Alice', 'Bob', 'Carol'], 'age': [25, 30, 35]})
df2 = pd.DataFrame({'name': ['Alice', 'David', 'Eve'], 'occupation': ['Software Engineer', 'Data Scientist', 'Product Manager']})
merged_df = df1.merge(df2, on='name')
print(merged_df)
Using the join() method
The join() method takes two DataFrames as input and returns a new DataFrame that is the joined result of the two input DataFrames. The join() method can only be used to perform inner joins.
Here is an example of how to use the join() method to merge two DataFrames:
import pandas as pd
df1 = pd.DataFrame({'name': ['Alice', 'Bob', 'Carol'], 'age': [25, 30, 35]})
df2 = pd.DataFrame({'name': ['Alice', 'David', 'Eve'], 'occupation': ['Software Engineer', 'Data Scientist', 'Product Manager']})
merged_df = df1.join(df2, on='name')
print(merged_df)
Which method you use to merge DataFrames in Pandas depends on your specific needs. If you need to perform a variety of merge types, the merge() method is more flexible. If you only need to perform inner joins, the join() method is more efficient.