In this article, we will discuss how to convert a dataframe into a list of lists, by converting either each row or column into a list and create a python list of lists from them.

First of all, create a dataframe,

Contents of the dataframe object studentDfObj are,

Convert a Dataframe into a list of lists – Rows Wise

In the above-created dataframe, we have to fetch each row as a list and create a list of these lists. Let’s do all that in a single line,

Output:

It converted the dataframe into a list of lists row-wise, i.e., each nested list contains a row of the dataframe. But what happened in a single line?

How did it work?

Let’s break the above single line into multiple lines to understand the concept behind it.

Step 1: Convert the Dataframe to a nested Numpy array using DataFrame.to_numpy() i.e.,

Output:

DataFrame.to_numpy()  converts a dataframe to a Numpy array. Therefore we got a 2D Numpy array here. We confirmed that by printing the type of the returned object.

Step 2: Convert 2D Numpy array into a list of lists

Numpy provides a function tolist(), which converts a Numpy Array into a list. Let’s call that function to the above created 2D Numpy array object,

Output:

It turned the 2D Numpy Array into a list of lists.

So, this is how we transformed a dataframe into a 2D Numpy Array and then into a List of Lists, where each nested list represents a row of the dataframe.

Convert a Dataframe into a list of lists – Column Wise

Contents of the dataframe studentDfObj are,

Now to convert each column into a list and create a list of these lists,

Output:

How did it work?

It worked on the same concept we discussed above, just one additional step here i.e.

Step 1: Transpose the dataframe to convert rows as columns and columns as rows

Output

tansposedDFObj is a a transpose of the original dataframe i.e. rows in studentDfObj are columns in  tansposedDFObj and columns in studentDfObj are rows in tansposedDFObj.

Step 2: Convert the Dataframe to a nested Numpy array using DataFrame.to_numpy()

Output

Step 3: Convert 2D Numpy array into a list of lists.

Output

It converted the 2D Numpy Array into a list of lists. So, this is how we transformed a dataframe into a 2D Numpy Array and then into a List of Lists, where each nested list represents a column of the dataframe.

The Complete example is as follows,

Output:

Python Resources

C++11 / C++14 Resources

Design Patterns Resources

If you didn't find what you were looking, then do suggest us in the comments below. We will be more than happy to add that.

Do Subscribe with us for more Articles / Tutorials like this,