How can I drop duplicates across multiple columns in Pandas?

How can I drop duplicates across multiple columns in Pandas?

Pandas is a popular Python library used for data analysis and manipulation. One common task in data analysis is removing duplicate values from a dataset. In Pandas, this can be achieved by using the “drop_duplicates” function. This function allows for the removal of duplicates across a single column or multiple columns. By specifying the columns to be checked for duplicates, Pandas will identify and remove any rows that have identical values in those columns. This process is useful for cleaning and organizing data, ensuring accuracy and efficiency in data analysis.

Pandas: Drop Duplicates Across Multiple Columns


You can use the following methods to drop duplicate rows across multiple columns in a pandas DataFrame:

Method 1: Drop Duplicates Across All Columns

df.drop_duplicates()

Method 2: Drop Duplicates Across Specific Columns

df.drop_duplicates(['column1', 'column3'])

The following examples show how to use each method in practice with the following pandas DataFrame:

import pandas as pd

#create DataFrame
df = pd.DataFrame({'region': ['East', 'East', 'East', 'West', 'West', 'West'],
                   'store': [1, 1, 2, 1, 2, 2],
                   'sales': [5, 5, 7, 9, 12, 8]})

#view DataFrame
print(df)

  region  store  sales
0   East      1      5
1   East      1      5
2   East      2      7
3   West      1      9
4   West      2     12
5   West      2      8

Example 1: Drop Duplicates Across All Columns

The following code shows how to drop rows that have duplicate values across all columns:

#drop rows that have duplicate values across all columns
df.drop_duplicates()

	region	store	sales
0	East	1	5
2	East	2	7
3	West	1	9
4	West	2	12
5	West	2	8

The row in index position 1 had the same values across all columns as the row in index position 0, so it was dropped from the DataFrame.

By default, pandas keeps the first duplicate row. However, you can use the keep argument to specify to keep the last duplicate row instead:

#drop rows that have duplicate values across all columns (keep last duplicate)
df.drop_duplicates(keep='last')

	region	store	sales
1	East	1	5
2	East	2	7
3	West	1	9
4	West	2	12
5	West	2	8

Example 2: Drop Duplicates Across Specific Columns

You can use the following code to drop rows that have duplicate values across only the region and store columns:

#drop rows that have duplicate values across region and store columns
df.drop_duplicates(['region', 'store'])

	region	store	sales
0	East	1	5
2	East	2	7
3	West	1	9
4	West	2	12

A total of two rows were dropped from the DataFrame because they had duplicate values in the region and store columns.

Additional Resources

The following tutorials explain how to perform other common operations in pandas:

Cite this article

stats writer (2024). How can I drop duplicates across multiple columns in Pandas?. PSYCHOLOGICAL SCALES. Retrieved from https://scales.arabpsychology.com/stats/how-can-i-drop-duplicates-across-multiple-columns-in-pandas/

stats writer. "How can I drop duplicates across multiple columns in Pandas?." PSYCHOLOGICAL SCALES, 1 Jul. 2024, https://scales.arabpsychology.com/stats/how-can-i-drop-duplicates-across-multiple-columns-in-pandas/.

stats writer. "How can I drop duplicates across multiple columns in Pandas?." PSYCHOLOGICAL SCALES, 2024. https://scales.arabpsychology.com/stats/how-can-i-drop-duplicates-across-multiple-columns-in-pandas/.

stats writer (2024) 'How can I drop duplicates across multiple columns in Pandas?', PSYCHOLOGICAL SCALES. Available at: https://scales.arabpsychology.com/stats/how-can-i-drop-duplicates-across-multiple-columns-in-pandas/.

[1] stats writer, "How can I drop duplicates across multiple columns in Pandas?," PSYCHOLOGICAL SCALES, vol. X, no. Y, ص Z-Z, July, 2024.

stats writer. How can I drop duplicates across multiple columns in Pandas?. PSYCHOLOGICAL SCALES. 2024;vol(issue):pages.

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