Adventures in Machine Learning

Unleashing the Power of pandasunique() function: A Comprehensive Guide

Python has become one of the most widely used programming languages today, due to its wide range of applications and versatility. Python’s data management capabilities are unmatched, thanks primarily to its pandas module.

Pandas can accurately handle and analyse large datasets with relative ease. One of its key features is the DataFrame, which is a 2D, size-mutable, tabular data structure widely used for data processing.

In this article, we will explore pandas.unique() function, which is used to extract non-redundant values from a dataframe. Functionality of pandas.unique():

Before delving further, let’s understand how pandas.unique() works and why it is important.

Simply put, it searches the specified dataset for unique values and returns them in a sorted format. These values can then be used for further analysis or manipulation.

When a dataset is designed, it is essential to ensure that data redundancy is kept to a minimum. A large dataset with many, unnecessary, duplicate values can significantly slow down processing times and make analysis challenging.

That’s where pandas.unique() comes into play. It allows for quick and accurate identification of unique values in a given data frame.

Working of pandas.unique():

pandas.unique() uses a hash table internally to efficiently store the non-redundant values from the dataframe. The hash table feature ensures that lookup times are fast even for complex datasets, and this optimization allows pandas.unique() to function smoothly even when dealing with large datasets.

To illustrate the usage, consider a basic dataset containing the following data:



0 1 x

1 4 y

2 2 x

3 1 y

4 2 x

5 2 z


The dataset identifies three columns, namely, A, B, and C. To demonstrate the pandas.unique() function’s functionality with the dataset, we need to perform the following procedure in Python.


import pandas as pd

data = pd.read_csv(‘data.csv’)

df = pd.DataFrame(data)

unique_vals = pd.unique(df[‘C’])



The output retrieved from the pandas.unique() function on the dataset will be a sorted form of unique C-column values. The output would look like the following:


[‘x’ ‘y’ ‘z’]


Notice that the values are sorted alphabetically, purely from a formatting perspective, but the sorting happens based on the conceptual ordering of the values i.e., x, y, z.

The unique() procedure can also be used on other columns by simply replacing ‘C’ with the column of choice. This use-case extends far beyond the symmetric sorting of non-redundant values.


Overall, the pandas.unique() function has become a popular addition to the already rich Python Pandas library. With the evergrowing size of datasets, a function like pandas.unique() offers a quick solution for efficiently removing duplicates and non-essential data from the dataframes.

The ability of pandas.unique() to work with overlapping value datasets and produce clear and accessible results makes it an indispensable tool for data scientists and analysts all over the world. 3) Syntax of pandas.unique() Function

Pandas has two significant key data structures: Series and DataFrame.

Series represents a one-dimensional labeled array, while DataFrame represents a two-dimensional labeled data structure with columns of potentially different types. Knowing how to use pandas.unique() function appropriately is vital in analysing datasets using these two structures.

To obtain unique values from a 1-dimensional series data structure, we use pandas.unique() with no arguments. The syntax for doing this is as follows:


import pandas as pd

# Creating pandas series

s = pd.Series([2, 3, 4, 5, 2, 4, 6, 8, 4, 5, 7, 4, 2, 9])

# Using pandas unique function

unique_values = pd.unique(s)


The variable `unique_values` created with the above syntax would contain only the unique elements in the series object `s`.

For multi-dimensional categorical data, to get unique values from a specific column, use `pd.unique()` with the column name as an argument to the function.

The syntax is as follows:


import pandas as pd

# Creating multi-dimensional data structure

data = {‘name’:[‘John’, ‘Rick’, ‘Stacy’, ‘Sarah’, ‘Niko’], ‘age’:[20, 21, 19, 22, 21], ‘gender’:[‘M’, ‘M’, ‘F’, ‘F’, ‘M’]}

# Creating dataframe from data

df = pd.DataFrame(data)

# Finding unique values in a specific column

unique_values = pd.unique(df[‘gender’])


The variable `unique_values` would then only contain unique gender elements. Using this syntax ensures the extraction of only unique values, ensuring the data is well formatted for subsequent processing.

4) pandas.unique() Function with Pandas Series

Pandas.unique() function can also be used with a list that is converted to pandas series. The syntax to achieve this kind of implementation is as follows:


import pandas as pd

# Creating list containing values to be put into a pandas series

mylist = [1,2,3,4,5,6,6,7,8,9,10,10,11,12]

# Converting list to series

myseries = pd.Series(mylist)

# Finding unique values in series

unique_values = pd.unique(myseries)


When the code above is executed, the `unique_values` variable will contain only unique values from the original list. In this example, the output would contain numbers from 1 to 12 with no duplicates.

The use of pandas.unique() function on a list gives the desired effect of eliminating duplicates – creating a unique set of values that can be subsequently manipulated and analyzed. Conclusion:

The ability to extract unique values from a large dataset can significantly influence the efficiency of data processing.

Pandas presented a powerful solution to this challenge with the pandas.unique() function. When working with a 1-dimensional series data structure, the use of pandas unique with no arguments helps quickly extract unique values.

For multi-dimensional data structures, the use of pandas.unique() in conjunction with the specific column name grants efficient extraction of the unique values in that column. Finally, when working with a list data structure, simple conversions to Pandas Series object followed by the use of the pandas.unique() function, grants efficient extraction of unique values in a dataset.

These techniques make the effective use of pandas.unique() fundamental in achieving accurate data analysis and improved data manipulation. 5) pandas.unique() Function with Pandas DataFrame

As previously discussed, the ability to extract unique values from a dataset is essential for efficient data processing and analysis.

Pandas provides several tools for working with datasets in data frames, including pandas.unique() function. Now, we will discuss how to use pandas.unique() function with pandas data frames.

Loading a dataset into Python environment using Pandas:

Before working with a data frame in Python environment, the first step is to load the dataset that contains the data frame. Pandas library provides several ways to load a dataset into the Python environment.

The most popular method is to use pd.read_csv() function to load a dataset saved in a CSV format into a pandas data frame. Other formats that can be loaded into a data frame include Excel (.xls), tab-separated values (.tsv), amongst others.

Consider the following dataset that contains data about customers purchasing behavior:


import pandas as pd

# Loading DataFrame

df = pd.read_csv(‘customer_data.csv’)

# Printing first 5 rows of the data frame



The code above loads the customer_data.csv file into a data frame named ‘df and prints the first five rows of the data frame. Using pandas.dataframe.nunique() to get unique values from all columns of a DataFrame:

pandas.dataframe.nunique() function identifies the number of unique values in each column of a data frame.

The function returns a series object containing the unique values count for each column. “`python

# Finding unique values in all columns of data frame

unique_values = df.nunique()


By executing the code above, the ‘unique_values’ object will contain the number of unique values that occur in each column of the data frame.

Using pandas.unique() to get unique values from a specific column of a DataFrame:

In some data analysis situations, we might need to extract unique values from a specific column in a data frame. In such cases, we need to use the pandas.unique() function.

As explained earlier, the syntax for performing unique() on a data frame is:


# Finding unique values in a specific column of data frame

unique_values = pd.unique(df[‘column_name’])


In the code above, we used pd.unique() function to extract unique values from the ‘column_name’ column of the ‘df’ data frame. By executing the code above, the ‘unique_values’ object will contain an array of unique values that exist in the column specified.


In this article, we covered the usage of pandas.unique() function with pandas data frames. We began with the basics of loading datasets into Python environment using Pandas and proceeded to show how to use pandas.dataframe.nunique() function to get unique values from all columns of a data frame.

Additionally, we demonstrated how to use pandas.unique() function to get unique values from a specific column of a data frame. These functions provide a powerful data processing feature set that is essential for efficient data analysis and manipulation.

Use of these techniques is fundamental in achieving quality data analysis while ensuring that data is in a uniform state for statistical evaluation. In conclusion, Pandas.unique() function is an essential tool when it comes to data processing and analysis.

The function allows us to quickly extract non-redundant values from both one and multi-dimensional datasets. In addition, we can use Pandas to separate unique values across multiple columns.

Using these techniques, we can effectively clean up data and streamline data processing. As data processing continues to grow in importance, it’s essential to master Pandas.unique() function to extract unique values and process data accurately and efficiently.

Popular Posts