How to Rename Pandas DataFrame Index Names?

Renaming Pandas DataFrame Index

This question pertains to renaming both the index and column names of a DataFrame. While the df.rename() method can modify column names, it faces difficulty when it comes to renaming the index.

The key to understanding this issue lies in the distinction between index values and index names. The df.rename() method operates on index values, while the desired operation involves modifying index names.

To successfully rename index names, utilize the following syntax:

<code class="python">df.index.names = ['NewName']</code>

For a more comprehensive understanding, consider the following examples:

1. Rename index name:

<code class="python">df = pd.DataFrame([[1, 2, 3], [4, 5, 6]], columns=list('ABC'))
df.index.names = ['Date']</code>

2. Rename index value:

<code class="python">df1 = df.set_index('A')
df1.rename(index={1: 'a'})</code>

3. Rename column name:

<code class="python">df1.rename(columns={'B': 'BB'})</code>

It's crucial to note that index names are similar in concept to column names, as both are instances of the same object type (Index or MultiIndex). This equivalence allows for interchangeability between columns and index via transpose.

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