Ranking Rows of Pandas DataFrame

Ranking rows in a Pandas DataFrame assigns a numerical rank to each row based on the values in a column. Higher or lower values can be ranked first depending on the requirement.

For example, given a small dataset of students’ scores, we can rank them to see who scored highest and lowest.

 Student Marks Rank
0 Emily 85 2.0
1 Ava 92 1.0
2 Jack 78 3.0

Explanation:

• df['Marks'].rank(ascending=0) ranks the students from highest to lowest marks.
• The student with the highest mark (Ava) gets rank 1.

Syntax

DataFrame.rank(axis=0, method='average', ascending=True)

Parameters:

• axis: 0 for row-wise (default), 1 for column-wise.
• method: How to assign ranks to equal values ('average', 'min', 'max', 'first').
• ascending: True for lowest values first, False for highest first.

Return Value: Returns a Series or DataFrame containing ranks.

Examples

Example 1: In this example, we rank movies from lowest to highest rating using the rank() method.

Output

Movie Year Rating Rank_Asc
1 Bird Box 2018 6.8 1.0
4 Titanic 1997 7.8 2.0
3 Inception 2010 8.7 3.0
2 Fight Club 1999 8.8 4.0
0 The Godfather 1972 9.2 5.0

Explanation:

• df['Rating'].rank(ascending=True) computes rank based on the Rating column, lowest value first.
• sort_values('Rank_Asc') orders the DataFrame by the new rank column.
• Bird Box has rank 1 as it has the lowest rating.

Example 2: This code ranks movies from highest to lowest rating to find the top-rated movie.

Output

Movie Year Rating Rank_Desc
0 The Godfather 1972 9.2 1.0
2 Fight Club 1999 8.8 2.0
3 Inception 2010 8.7 3.0
4 Titanic 1997 7.8 4.0
1 Bird Box 2018 6.8 5.0

Explanation:

• rank(ascending=False) assigns rank 1 to the highest rating.
• The highest-rated movie, The Godfather, now has rank 1.
• Sorting by Rank_Desc shows movies in order from top-rated to lowest-rated.

Example 3: Here we rank movies using the 'min' method, which gives tied ratings the minimum possible rank.

Output

Movie Year Rating Rank_Min
0 The Godfather 1972 9.2 1.0
2 Fight Club 1999 8.8 2.0
5 Movie X 2020 8.8 2.0
3 Inception 2010 8.7 4.0
4 Titanic 1997 7.8 5.0
1 Bird Box 2018 6.8 6.0

Explanation:

• Added a new movie with rating 8.8 to demonstrate ties.
• method='min' assigns the lowest possible rank to tied values.
• Both Fight Club and Movie X share rank 2.