Creating a New Column in Pandas DataFrame Based on Multiple Conditions

Описание: Learn how to create a new column in a Pandas DataFrame by analyzing values from existing columns using dictionaries for conditional assignments.
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Creating a New Column in Pandas DataFrame Based on Multiple Conditions

When working with data in Python, leveraging libraries like Pandas is essential for efficient data manipulation. One common task you may encounter is the need to create a new column in a DataFrame based on the values of existing columns. In this guide, we’ll explore how to achieve this by using a function that incorporates logic based on predefined dictionaries.

The Problem

Imagine you have a DataFrame that contains information about dog breeds and their respective types. You want to enrich this DataFrame by assigning a color to each dog based on both its type and breed. Here's a simplified view of the DataFrame in question:

[[See Video to Reveal this Text or Code Snippet]]

The goal is to add a new column that indicates the color of each dog according to certain rules defined in dictionaries as follows:

[[See Video to Reveal this Text or Code Snippet]]

The Solution

Step 1: Define the Function

To create the new column, we first need to define a function that checks the breed of each dog and returns the corresponding color from the dictionaries. Here’s how to implement that:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Apply the Function to the DataFrame

Once the function is defined, we can apply it to the 'breed' column of our DataFrame to create the new 'colour' column:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Review the Results

Now let’s see how our DataFrame has changed after adding the color information:

[[See Video to Reveal this Text or Code Snippet]]

The output will look like this:

[[See Video to Reveal this Text or Code Snippet]]

Summary

Adding a new column to a DataFrame based on specific conditions can be accomplished efficiently in Pandas with functions and dictionaries.

Define your rules: Clearly outline your conditions in dictionaries.

Create a function: This function will evaluate existing values and return the corresponding new value.

Apply the function: Use the map method to create the new column easily.

By following these structured steps, you can adapt the same logic to other DataFrames that have similar structures. Happy coding!