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One can obtain the top N rows for each group in a Pandas DataFrame by using the “groupby” function to group the data based on a specific column or set of columns. Then, the “apply” function can be used to apply a function, such as “head(N)”, which will return the top N rows for each group. This method allows for efficient and organized retrieval of data from a large DataFrame based on specific groupings.
Pandas: Get Top N Rows by Group
You can use the following basic syntax to get the top N rows by group in a pandas DataFrame:
df.groupby('group_column').head(2).reset_index(drop=True)
This particular syntax will return the top 2 rows by group.
Simply change the value inside the head() function to return a different number of top rows.
The following examples show how to use this syntax with the following pandas DataFrame:
import pandas as pd #create DataFrame df = pd.DataFrame({'team': ['A', 'A', 'A', 'A', 'A', 'B', 'B', 'B', 'B', 'B'], 'position': ['G', 'G', 'G', 'F', 'F', 'G', 'G', 'F', 'F', 'F'], 'points': [5, 7, 7, 9, 12, 9, 9, 4, 7, 7]}) #view DataFrame print(df) team position points 0 A G 5 1 A G 7 2 A G 7 3 A F 9 4 A F 12 5 B G 9 6 B G 9 7 B F 4 8 B F 7 9 B F 7
Example 1: Get Top N Rows Grouped by One Column
The following code shows how to return the top 2 rows, grouped by the team variable:
#get top 2 rows grouped by team
df.groupby('team').head(2).reset_index(drop=True)
team position points
0 A G 5
1 A G 7
2 B G 9
3 B G 9
The output displays the top 2 rows, grouped by the team variable.
Example 2: Get Top N Rows Grouped by Multiple Columns
The following code shows how to return the top 2 rows, grouped by the team and position variables:
#get top 2 rows grouped by team and position
df.groupby(['team', 'position']).head(2).reset_index(drop=True)
team position points
0 A G 5
1 A G 7
2 A F 9
3 A F 12
4 B G 9
5 B G 9
6 B F 4
7 B F 7The output displays the top 2 rows, grouped by the team and position variables.
The following tutorials explain how to perform other common operations in pandas:
Cite this article
stats writer (2024). How can I get the top N rows for each group in a Pandas DataFrame?. PSYCHOLOGICAL SCALES. Retrieved from https://scales.arabpsychology.com/stats/how-can-i-get-the-top-n-rows-for-each-group-in-a-pandas-dataframe/
stats writer. "How can I get the top N rows for each group in a Pandas DataFrame?." PSYCHOLOGICAL SCALES, 27 Jun. 2024, https://scales.arabpsychology.com/stats/how-can-i-get-the-top-n-rows-for-each-group-in-a-pandas-dataframe/.
stats writer. "How can I get the top N rows for each group in a Pandas DataFrame?." PSYCHOLOGICAL SCALES, 2024. https://scales.arabpsychology.com/stats/how-can-i-get-the-top-n-rows-for-each-group-in-a-pandas-dataframe/.
stats writer (2024) 'How can I get the top N rows for each group in a Pandas DataFrame?', PSYCHOLOGICAL SCALES. Available at: https://scales.arabpsychology.com/stats/how-can-i-get-the-top-n-rows-for-each-group-in-a-pandas-dataframe/.
[1] stats writer, "How can I get the top N rows for each group in a Pandas DataFrame?," PSYCHOLOGICAL SCALES, vol. X, no. Y, ص Z-Z, June, 2024.
stats writer. How can I get the top N rows for each group in a Pandas DataFrame?. PSYCHOLOGICAL SCALES. 2024;vol(issue):pages.
