How do I join two DataFrames in Pandas?

How do I join two DataFrames in Pandas?

You can use the merge() function to join two DataFrames. What type of join do you need: inner, outer, left, or right?

I need to perform a left join. Can you show me an example?

Sure! Here's an example:

import pandas as pd

df1 = pd.DataFrame({'key': ['A', 'B', 'C'], 'value1': [1, 2, 3]})
df2 = pd.DataFrame({'key': ['A', 'B', 'D'], 'value2': [4, 5, 6]})

result = pd.merge(df1, df2, on='key', how='left')
print(result)

What will the output look like?

The output will look like this:

  key  value1  value2
0   A       1     4.0
1   B       2     5.0
2   C       3     NaN

The 'C' row has NaN for value2 because there was no matching key in df2.