How To Add A Column To A Dataframe In Python?

When it comes to creating data frames in python, it comes down to how well you can use Panda. This is python’s data frame, which acts as a manipulation library.

It is an excellent tool that allows easy data analysis when necessary. There are a range of functions within Panda, which can be used for interpreting table results, outcomes of an experiment, and more. 

There are four different ways of adding a new column to any data frame within python’s Panda format.

Each take slightly different amounts of time and input, and they have been listed below.

Whether you are just starting out with python, or if you are more experienced, here are four of the best ways that you can add a column to a data frame in python. 

Adding A Column At A Specific Index

Firstly, you can add a column at particular places within the table on Panda using this method. This is done by using the insert function to add the desired location for a column.

You will need to input the values, name of the column, and the index in order to correctly create and allocate a column. 

If you want to create a continuous sequence of numbers within this column, you can add a constant value that will fill each row accordingly.

To add the column, type df.insert (index, “name”, value). Where there are three words in the brackets, you will need to add your variables depending on the type of data that is on your table. 

Make sure each row and column has been labeled correctly in order to maximize the chances of doing this correctly with fewer errors. 

Assign Function

Another way that you can use Panda to add a column to your data frame in python is known as assign. You can do this using df = df. assign ( F = df.C*V ).

In this case, C is used to represent the intended column name, and V represents the value that you want to assign to it. 

Remember that there is a difference between the insert and assign functions.

You may need to make additional changes so that the newly added column is permanently saved onto your data frame. The modified data frame is typically separated from the original. 

While this has some advantages, it tends to be more of a hindrance. Check that you have everything in the correct areas using the assign function.

This will need to be done by explicitly assigning the modified version with the new column. 

Adding Multiple Columns 

The next method is the most widely used one, because of how easy it is to master. Because of this, you can use the assign function for a range of different data types.

You will need to add the column name and values, then the new column will be added with the highest index on the table. 

This may seem a little complicated, but it allows you to fill more of the table at once. Use the function df [“C”] = [1, 2, 3, 4] to create the new column.

Like the other examples, C represents the column name, and the numbers 1-4 are where you would need to add your values in appropriate order. 

In order to add several columns at the same time, you can change C in the formula above to “1of3, 2of3, 3of3” before adding your values.

The process becomes slightly more complicated in this way, which is why it can be easier to assign random numbers to each of these columns and change the values afterwards.

Say you were making three new columns in a four by three table, you would need to use df [[“1of3, 2of3, 3of3”]] = np.random.randit (10, size= (4,3)).

Once this has been done, you can go ahead and change the values to agree with your data. It can be useful for representing larger amounts of data, as less input is needed in general. 

Loc Method

The final method of adding a new column is known as the loc method. This relies on information that is already on the table to create a new column with relevant details.

By inserting the label of a column that isn’t actually there yet, Panda will create one! 

Say the columns of your table are currently in alphabetical order from A-C, and you used the loc method formula with column D, which doesn’t currently exist.

The program will add this to the list of columns so that you don’t have to. 

To test this out for yourself, try using the formula df.loc [: , “D”] = list (“abc”). If everything is working correctly, then python should create a new column with the name D, in continuation with the existing columns labeled A-C.

This is because the loc method is commonly known for being a useful way of selecting multiple rows and columns based on their labels. 

Summary

When it comes to adding columns to a data frame in python, there are different routes you can choose to go down.

Each is appropriate for a different type of usage. Because of this, it could be worth taking a closer look at your data and figuring out what type of category it would fall into. 

For example, larger bodies of data can be highly challenging to input and categorize, so the most efficient approach could be to add multiple columns at once.

If you are more concerned about getting the figures accurate and ensuring that the data is correct, then you could choose the index or assign function method. 

The great thing about using python for data analysis and input is that there are a huge amount of options available.

This means that it can generate a range of figures based on your data, and it can be used for a range of purposes. Consider using python’s Panda data frame setting in the future with the methods above.