Data structures

The core base data structures provided by Polars are Series and DataFrames.

Series

Series are a 1-dimensional data structure. Within a series all elements have the same Data Type . The snippet below shows how to create a simple named Series object.

{{code_block('getting-started/series-dataframes','series',['Series'])}}

python

--8<-- "python/getting-started/series-dataframes.py:series"

DataFrame

A DataFrame is a 2-dimensional data structure that is backed by a Series, and it can be seen as an abstraction of a collection (e.g. list) of Series. Operations that can be executed on a DataFrame are very similar to what is done in a SQL like query. You can GROUP BY, JOIN, PIVOT, but also define custom functions.

{{code_block('getting-started/series-dataframes','dataframe',['DataFrame'])}}

python

--8<-- "python/getting-started/series-dataframes.py:dataframe"

Viewing data

This part focuses on viewing data in a DataFrame. We will use the DataFrame from the previous example as a starting point.

Head

The head function shows by default the first 5 rows of a DataFrame. You can specify the number of rows you want to see (e.g. df.head(10)).

{{code_block('getting-started/series-dataframes','head',['head'])}}

python

--8<-- "python/getting-started/series-dataframes.py:head"

Tail

The tail function shows the last 5 rows of a DataFrame. You can also specify the number of rows you want to see, similar to head.

{{code_block('getting-started/series-dataframes','tail',['tail'])}}

python

--8<-- "python/getting-started/series-dataframes.py:tail"

Sample

If you want to get an impression of the data of your DataFrame, you can also use sample. With sample you get an n number of random rows from the DataFrame.

{{code_block('getting-started/series-dataframes','sample',['sample'])}}

python

--8<-- "python/getting-started/series-dataframes.py:sample"

Describe

Describe returns summary statistics of your DataFrame. It will provide several quick statistics if possible.

{{code_block('getting-started/series-dataframes','describe',['describe'])}}

python

--8<-- "python/getting-started/series-dataframes.py:describe"