AVG( ) in pandas

Posted by Kevin

Selecting the average of column values from a SQL table, translated to Python's pandas.

Selecting a single column's average value

In SQL:

SELECT 
  AVG(column_1) 
FROM 
  table;

In pandas:

table['column_1'].mean()

Selecting the average of multiple columns

In SQL:

SELECT 
  AVG(column_1), 
  AVG(column_2) 
FROM 
  table;

In pandas:

table
    .agg({'column_1': ['mean'], 'column_2': ['mean']})

Selecting the average of columns with an alias

In SQL:

SELECT 
  column_1, 
  AVG(column_2) AS agg_alias_1, 
  AVG(column_3) AS agg_alias_2 
FROM 
  table 
GROUP BY 
  column_1;

In pandas:

table 
    .groupby('column_1') 
    .agg(agg_alias_1=('column_2', 'mean'), agg_alias_2=('column_3', 'mean'))

References