Convert Pandas Series to a Dictionary

A dictionary is very useful to lookup values for certain keys. If you have a pandas series with a relevant index, you can create a python dict object with the “index: value” key-value pairs to quickly fetch values referred to by its index. In this tutorial, we will look at how to convert a pandas series to a python dictionary object.

To get a dictionary from a series, you can use the pandas series to_dict() function which returns a dictionary of “index: value” key-value pairs. The following is the syntax:

# using to_dict()
d = s.to_dict()

Here, s is the pandas series you want to convert to a dictionary. The returned dictionary will have the series’ index as its keys and the series’ value as its value.

Let’s look at some examples of using the above method to create a dictionary from a series. First, we’ll create a sample pandas series which we will be using throughout this tutorial.

import pandas as pd

# pandas series Wimbledon winners from 2015 to 2019
wimbledon_winners = pd.Series(index=[2015, 2016, 2017, 2018, 2019],
                   data=['Novak Djokovic', 'Andy Murray', 'Roger Federer', 'Novak Djokovic', 'Novak Djokovic'],
                   name='Name')

# display the series
print(wimbledon_winners)

Output:

2015    Novak Djokovic
2016       Andy Murray
2017     Roger Federer
2018    Novak Djokovic
2019    Novak Djokovic
Name: Name, dtype: object

You can see the contents of the series object above. Let’s confirm the type of the object.

# check the type
print(type(wimbledon_winners))

Output:

<class 'pandas.core.series.Series'>

We now have a pandas series containing the name of Wimbledon Winners from 2015 to 2019 with the year as its index.

You can use the pandas series to_dict() function to create a dictionary object from a series. Let’s use it to create a dictionary with the year as its key and the winners’ name as its value from the series “wimbledon_winners” –

winners_dict = wimbledon_winners.to_dict()
# check the type
print(type(winners_dict))
# print the content
print(winners_dict)

Output:

<class 'dict'>
{2015: 'Novak Djokovic', 2016: 'Andy Murray', 2017: 'Roger Federer', 2018: 'Novak Djokovic', 2019: 'Novak Djokovic'}

You can see that here the pandas series to_dict() function returns a dictionary of the “Year: Name” key-value pairs. In our case, we can use the above dictionary to quickly fetch results to questions like “Who was the Wimbledon winner in the year 2017?”

print(winners_dict[2017])

Output:

Roger Federer

We get the name corresponding to the key 2017 from the dictionary, “Roger Federer”.

For more on the pandas series to_dict() function, refer to its documentation.

With this, we come to the end of this tutorial. The code examples and results presented in this tutorial have been implemented in a Jupyter Notebook with a python (version 3.8.3) kernel having pandas version 1.0.5


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