π¬ **Programming Challenge**: Given a Pandas DataFrame or a Pandas Series object. How to convert them to a NumPy array?

In this short tutorial, you’ll learn (1) how to **convert a 1D pandas Series** to a NumPy array, and (2) how to **convert a 2D pandas DataFrame** to an array. Let’s get started with the first! π

## Convert Pandas Series to NumPy Array

First, let’s create a Pandas Series.

import pandas as pd # create dataframe df df = pd.Series([22,21,20,14], name= 'GSTitles', index= ['Nadal','Djokovic','Federer','Sampras']) print(df)

Here’s the resulting Series `df`

:

Nadal 22 Djokovic 21 Federer 20 Sampras 14 Name: GSTitles, dtype: int64

Now that we have our Pandas Series, you can convert this to a NumPy Array using the `DataFrame.to_numpy()`

method.

Like so:

print(df.to_numpy()) # [22 21 20 14]

The resulting object is a NumPy array:

print(type(df.to_numpy())) # <class 'numpy.ndarray'>

β‘ **Attention**: There is also the `.values()`

method, but that is being deprecated now – when you look at the Pandas documentation, there is a warning *“We recommend using DataFrame.to_numpy instead”*.

With this method, only the values in the DataFrame or Series will return. The index labels will be removed.

Here’s how that’ll work:

print(df.values) # [22 21 20 14]

This was a 1-dimensional array or a Series. Let’s move on to the 2D case next. πππ

## Convert DataFrame to NumPy Array

π¬ **Question**: Let’s try with a two-dimensional DataFrame — how to convert it to a NumPy array?

First, let’s print the dimension of the previous Series to confirm that it was, indeed, a 1D data structure:

print(df.ndim) # 1

Next, you create a 2D DataFrame object:

import pandas as pd # Create a 2D DataFrame object df2 = pd.DataFrame(data={'Nadal': [2, 14, 2, 4], 'Djokovic': [9, 2, 7, 3], 'Federer': [6, 1, 8, 5], 'Sampras': [2, 0, 7, 5]}, index=['AO', 'F', 'W', 'US']) print(df2)

Here’s the resulting DataFrame:

Nadal | Djokovic | Federer | Sampras | |
---|---|---|---|---|

AO | 2 | 9 | 6 | 2 |

F | 14 | 2 | 1 | 0 |

W | 2 | 7 | 8 | 7 |

US | 4 | 3 | 5 | 5 |

Now, let’s dive into the conversion of this DataFrame to a NumPy array by using the `DataFrame.to_numpy()`

method.

# Convert this DataFrame to a NumPy array print(df2.to_numpy())

The output shows a NumPy array from the 2D DataFrame — great! πΎ

[[ 2 9 6 2] [14 2 1 0] [ 2 7 8 7] [ 4 3 5 5]]

You can see that all indexing metadata has been stripped away from the resulting NumPy array!

## Convert Specific Columns from DataFrame to NumPy Array

You can also convert specific columns of a Pandas DataFrame by accessing the columns using pandas indexing and calling the `.to_numpy()`

method on the resulting view object.

Here’s an example:

print(df2[['Djokovic', 'Federer']].to_numpy())

The output:

[[9 6] [2 1] [7 8] [3 5]]

## Summary

You can convert a Pandas DataFrame or a Pandas Series object to a NumPy array by means of the `df.to_numpy()`

method. The indexing metadata will be removed.

You can also convert specific columns of a Pandas DataFrame by accessing the columns using pandas indexing and calling the `.to_numpy()`

method on the resulting view object.

Thanks for reading through the whole tutorial! π