Pandas Series: nsmallest() function

Last update on September 15 2022 12:54:14 (UTC/GMT +8 hours)

Get the smallest n elements in Pandas

The nsmallest() function is used to get the smallest n elements.

Syntax:

Series.nsmallest(self, n=5, keep='first')

Parameters:

Name	Description	Type/Default Value	Required / Optional
n	Return this many ascending sorted values.	int Default Value: 5	Required
keep	When there are duplicate values that cannot all fit in a Series of n elements: first : return the first n occurrences in order of appearance. last : return the last n occurrences in reverse order of appearance. all : keep all occurrences. This can result in a Series of size larger than n.	{‘first’, ‘last’, ‘all’} Default Value: ‘first’	Required

Returns: The n smallest values in the Series, sorted in increasing order.

Notes: Faster than .sort_values().head(n) for small n relative to the size of the Series object.

Example:

Python-Pandas Code:

import numpy as np
import pandas as pd
countries_population = {"Italy": 60550000, "France": 65130728,
                        "Russia": 435000, "Iceland": 435000,
                        "Palau": 435000, "Brazil": 21104900,
                        "Nauru": 11600, "Tuvalu": 11600,
                        "Bermuda": 11600, "Tokelau": 1440}
s = pd.Series(countries_population)
s

Output:

Italy      60550000
France     65130728
Russia       435000
Iceland      435000
Palau        435000
Brazil     21104900
Nauru         11600
Tuvalu        11600
Bermuda       11600
Tokelau        1440
dtype: int64

Example - The n smallest elements where n=5 by default:

Python-Pandas Code:

import numpy as np
import pandas as pd
countries_population = {"Italy": 60550000, "France": 65130728,
                        "Russia": 435000, "Iceland": 435000,
                        "Palau": 435000, "Brazil": 21104900,
                        "Nauru": 11600, "Tuvalu": 11600,
                        "Bermuda": 11600, "Tokelau": 1440}
s = pd.Series(countries_population)
s.nsmallest()

Output:

Tokelau      1440
Nauru       11600
Tuvalu      11600
Bermuda     11600
Russia     435000
dtype: int64

Example - The n smallest elements where n=3. Default keep value is ‘first’ so Nauru and Tuvalu will be kept:

Python-Pandas Code:

import numpy as np
import pandas as pd
countries_population = {"Italy": 60550000, "France": 65130728,
                        "Russia": 435000, "Iceland": 435000,
                        "Palau": 435000, "Brazil": 21104900,
                        "Nauru": 11600, "Tuvalu": 11600,
                        "Bermuda": 11600, "Tokelau": 1440}
s = pd.Series(countries_population)
s.nsmallest(3)

Output:

Tokelau     1440
Nauru      11600
Tuvalu     11600
dtype: int64

Example - The n smallest elements where n=3 and keeping the last duplicates. Bermuda and Tuvalu will be kept since they are the last with value 11600 based on the index order:

Python-Pandas Code:

import numpy as np
import pandas as pd
countries_population = {"Italy": 60550000, "France": 65130728,
                        "Russia": 435000, "Iceland": 435000,
                        "Palau": 435000, "Brazil": 21104900,
                        "Nauru": 11600, "Tuvalu": 11600,
                        "Bermuda": 11600, "Tokelau": 1440}
s = pd.Series(countries_population)
s.nsmallest(3, keep='last')

Output:

Tokelau     1440
Bermuda    11600
Tuvalu     11600
dtype: int64

Example - The n smallest elements where n=3 with all duplicates kept. Note that the returned Series has four elements due to the three duplicates:

Python-Pandas Code:

import numpy as np
import pandas as pd
countries_population = {"Italy": 60550000, "France": 65130728,
                        "Russia": 435000, "Iceland": 435000,
                        "Palau": 435000, "Brazil": 21104900,
                        "Nauru": 11600, "Tuvalu": 11600,
                        "Bermuda": 11600, "Tokelau": 1440}
s = pd.Series(countries_population)
s.nsmallest(3, keep='all')

Output:

Tokelau     1440
Nauru      11600
Tuvalu     11600
Bermuda    11600
dtype: int64

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