How to Query Distinct Count in Pandas Using \'nunique()\'?

Querying Distinct Count in Pandas Using 'nunique()'

To perform a count of distinct values in Pandas, similar to the 'count(distinct)' function in SQL, use the 'nunique()' method.

The syntax for 'nunique()' is:

dataframe.groupby(groupby_column).column_to_count.nunique()

Example:

To count the distinct clients per year in a Pandas DataFrame named 'table':

table.groupby('YEARMONTH').CLIENTCODE.nunique()

Explanation:

• table.groupby('YEARMONTH') groups the DataFrame by the 'YEARMONTH' column.
• CLIENTCODE selects the column to count distinct values.
• nunique() returns the number of distinct values in 'CLIENTCODE' for each group.

Output:

The output of the query will be a series with the 'YEARMONTH' as the index and the count of distinct 'CLIENTCODE' values as the values.

YEARMONTH
201301       2
201302       3

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