Foundation

The index column is to specify an index in one column of the data frame, which is the key used to find the value of the heat. The index column plays an important role in data analysis and operation, and is essential for efficiently processing and inquiring data.

Index column settings and release

To set an index column set_index() Use the method. for example, df Data frame id To set the heat to an index, use:

df.set_index('id', inplace=True)

To release the index column reset_index() Use the method. for example, df To release the index column of the data frame, use:

df.reset_index(inplace=True)

Index column format

The format of the index column should be the same as the heat form of the data frame. for example, df Data frame id If the heat is integer type, the index column must be integer. To change the index column format astype() Use the method.

Whether to allow duplicate index columns

Index columns do not allow duplicate by default. In other words, only one row with the same index value is allowed. To allow duplicate values to the index column duplicates() Use the method.

Index column and data alignment

To align data according to the index column sort_index() Use the method. for example, df Row of data frame id To sort in ascending order according to the index column, use:

df.sort_index(inplace=True)

Advantages of using index columns

The advantages of using index columns include:

Search and improve data search and views
Improvement of data analysis and statistical analysis
Data sorting and grouping of ease of grouping
Data security and integrity improvement

Notes on using index columns

The precautions for using index columns include:

If the redundant value of the index column is not allowed, the row with that value is removed from the data frame.
When the index column is changed, the structure of the data frame can be changed.
If the index column is in a text format, search and view speed can be slowed down.

Example of use of index columns

The index column can be used in various situations:

Set the heat that becomes a unique identifier as an index.
Set the heat that can be a data sorting and grouping criteria.
Set the heat that is the standard for data analysis and statistical analysis.
Set important columns to indexes to maintain data security and integrity.

Additional information about the index column

For more information about the index column, Pandas documentSee.

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