How to add a new column to an existing DataFrame?

How to Add a New Column to an Existing DataFrame 📊❓

So, you have an existing DataFrame and you want to add a new column to it without altering the rest of the DataFrame. 🤔 Don't worry! I've got you covered with some easy solutions. Let's dive in! 💪💡

The Scenario 📋

Here's the situation. You have an indexed DataFrame with named columns and non-continuous row numbers:

a         b         c         d
2  0.671399  0.101208 -0.181532  0.241273
3  0.446172 -0.243316  0.051767  1.577318
5  0.614758  0.075793 -0.451460 -0.012493

You also have a new column, let's call it 'e', with the following values:

0   -0.335485
1   -1.166658
2   -0.385571
dtype: float64

Now, your goal is to add the column 'e' to the existing DataFrame. How can you achieve this? 🤷‍♂️

Solution #1: Using Bracket Notation and Assigning Values 🚀

One way to add a new column is by using bracket notation ([]) and assigning values to it. Here's how you can do it:

# Let's assume your DataFrame is named 'df'
df['e'] = [-0.335485, -1.166658, -0.385571]

By specifying df['e'], you are creating a new column named 'e' in the DataFrame df and assigning the values [-0.335485, -1.166658, -0.385571] to it. The DataFrame will be updated with the new column:

a         b         c         d         e
2  0.671399  0.101208 -0.181532  0.241273 -0.335485
3  0.446172 -0.243316  0.051767  1.577318 -1.166658
5  0.614758  0.075793 -0.451460 -0.012493 -0.385571

And voila! You have successfully added a new column 'e' to your DataFrame. Pretty neat, right? 😎

Solution #2: Using the assign() Method 🎯

If you prefer a more concise solution, you can use the assign() method provided by pandas. Here's how you can do it:

# Let's assume your DataFrame is named 'df'
df = df.assign(e=[-0.335485, -1.166658, -0.385571])

By using the assign() method, you can specify the new column name 'e' and assign the corresponding values. The original DataFrame df will be updated with the new column, just like in Solution #1.

📣 Call-to-Action: Share Your Thoughts! 📢

Adding a new column to an existing DataFrame doesn't have to be a daunting task. With these easy solutions, you can enhance your data analysis and manipulation capabilities.

Now that you know the tricks, try them out for yourself! Share your experience or any other cool DataFrame tips in the comments below. Let's geek out together! 💬🤓

Cheers to DataFrame transformations and happy coding! 🎉🐍