Counting And Retrieving Unique Elements From A Pandas.Series Object

Overview:

  • The count() function returns the number of elements present in a pandas.Series instance.The NA/null/None values are not included in the count value.
  • The nunique() function returns the number of unique elements present in the pandas.Series.
  • The function Series.unique() returns the unique elements excluding the duplicate values present in a pandas.Series. Determining uniqueness of the elements is done through a hash table.
     

Example - Counting elements of a pandas.series:

# Example Python program to count the number of

# elements present in a pandas.Series instance

import pandas as pds

 

cities = ["London", "Paris", "Madrid", "NewYork", "Chicago", "San Francisco"];

 

# Create a pandas.Series instance

series = pds.Series(cities);

print("Contents of the pandas.series:");

print(cities);

 

print("Number of elements present in the pandas.series:");

print(series.count());

 

Output:

Contents of the pandas.series:

['London', 'Paris', 'Madrid', 'NewYork', 'Chicago', 'San Francisco']

Number of elements present in the pandas.series:

6

 

Example-Count and get the unique elements present in a pandas.series:

# Example Python program to get unique elements present in a pandas.Series

import pandas as pds

 

# Create a pandas.Series instance

numbers = pds.Series([1,2,3,5,7,3,5,7,3,5,7]);

print("Contents of the Series:");

print(numbers);

 

print("Number of Unique elements present in the Series:");

print(numbers.nunique());

 

print("Unique elements of the Series:");

print(numbers.unique());

 

Output:

Contents of the Series:

0     1

1     2

2     3

3     5

4     7

5     3

6     5

7     7

8     3

9     5

10    7

dtype: int64

Number of Unique elements present in the Series:

5

Unique elements of the Series:

[1 2 3 5 7]

 

 

Example- Get the unique class objects present in a pandas.series:

# Example Python program to get unique elements present in a pandas.Series

import pandas as pds

 

class X:

    def __init__(self, name):

        self.name = name;

   

    def __str__(self):

        return self.name;

 

# Unique elements

x1 = X("x1");

x2 = X("x2");

x3 = X("x3");

 

# Copy

x4 = x1;

 

# Copy is not returned as identity of x1 and x4 are same

xSeries = pds.Series([x1, x2, x3, x4]);

uniques = xSeries.unique();

 

print("Unique objects:");

print(uniques);

 

# First and fourth elements have indeed different identities

xDashSeries = pds.Series([X("One"), X("Two"), X("Three"), X("One")]);

uniques = xDashSeries.unique();

 

print("Unique objects:")

print(uniques);

 

Output:

Unique objects:

[<__main__.X object at 0x1100db438> <__main__.X object at 0x1100db470>

 <__main__.X object at 0x1100db4a8>]

Unique objects:

[<__main__.X object at 0x11c0a8da0> <__main__.X object at 0x11d4fe0b8>

 <__main__.X object at 0x11d4fe048> <__main__.X object at 0x11d52a940>]

 


Copyright 2022 © pythontic.com