Let’s discuss how to add new columns to existing DataFrame in Pandas. There are multiple ways we can do this task.
Method #1: By declaring a new list as a column.
Note that the length of your list should match the length of the index column otherwise it will show an error.
Method #2: By using DataFrame.insert()
It gives the freedom to add a column at any position we like and not just at the end. It also provides different options for inserting the column values.
Method #3: Using Dataframe.assign() method
This method will create a new dataframe with new column added to the old dataframe.
Method #4: By using a dictionary
We can use a Python dictionary to add a new column in pandas DataFrame. Use an existing column as the key values and their respective values will be the values for new column.
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