pandas.DataFrame.nsmallest — pandas 2.2.3 documentation (original) (raw)

DataFrame.nsmallest(n, columns, keep='first')[source]#

Return the first n rows ordered by columns in ascending order.

Return the first n rows with the smallest values in columns, in ascending order. The columns that are not specified are returned as well, but not used for ordering.

This method is equivalent todf.sort_values(columns, ascending=True).head(n), but more performant.

Parameters:

nint

Number of items to retrieve.

columnslist or str

Column name or names to order by.

keep{‘first’, ‘last’, ‘all’}, default ‘first’

Where there are duplicate values:

• first : take the first occurrence.
• last : take the last occurrence.
• all : keep all the ties of the largest item even if it means selecting more than n items.

Returns:

DataFrame

Examples

df = pd.DataFrame({'population': [59000000, 65000000, 434000, ... 434000, 434000, 337000, 337000, ... 11300, 11300], ... 'GDP': [1937894, 2583560 , 12011, 4520, 12128, ... 17036, 182, 38, 311], ... 'alpha-2': ["IT", "FR", "MT", "MV", "BN", ... "IS", "NR", "TV", "AI"]}, ... index=["Italy", "France", "Malta", ... "Maldives", "Brunei", "Iceland", ... "Nauru", "Tuvalu", "Anguilla"]) df population GDP alpha-2 Italy 59000000 1937894 IT France 65000000 2583560 FR Malta 434000 12011 MT Maldives 434000 4520 MV Brunei 434000 12128 BN Iceland 337000 17036 IS Nauru 337000 182 NR Tuvalu 11300 38 TV Anguilla 11300 311 AI

In the following example, we will use nsmallest to select the three rows having the smallest values in column “population”.

df.nsmallest(3, 'population') population GDP alpha-2 Tuvalu 11300 38 TV Anguilla 11300 311 AI Iceland 337000 17036 IS

When using keep='last', ties are resolved in reverse order:

df.nsmallest(3, 'population', keep='last') population GDP alpha-2 Anguilla 11300 311 AI Tuvalu 11300 38 TV Nauru 337000 182 NR

When using keep='all', the number of element kept can go beyond nif there are duplicate values for the largest element, all the ties are kept.

df.nsmallest(3, 'population', keep='all') population GDP alpha-2 Tuvalu 11300 38 TV Anguilla 11300 311 AI Iceland 337000 17036 IS Nauru 337000 182 NR

However, nsmallest does not keep n distinct smallest elements:

df.nsmallest(4, 'population', keep='all') population GDP alpha-2 Tuvalu 11300 38 TV Anguilla 11300 311 AI Iceland 337000 17036 IS Nauru 337000 182 NR

To order by the smallest values in column “population” and then “GDP”, we can specify multiple columns like in the next example.

df.nsmallest(3, ['population', 'GDP']) population GDP alpha-2 Tuvalu 11300 38 TV Anguilla 11300 311 AI Nauru 337000 182 NR