How to Add Empty Column to Pandas DataFrame

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Samreena Aslam Feb 02, 2024
Pandas Pandas DataFrame
  1. Add Empty Columns in Pandas DataFrame Using the assignment operator
  2. Add an Empty Column in Pandas DataFrame Using the DataFrame.assign() Method
  3. Add an Empty Column in Pandas DataFrame Using the DataFrame.reindex() Method
  4. Add an Empty Column in Pandas DataFrame Using the DataFrame.insert() Method
  5. Add an Empty Column in Pandas DataFrame Using the DataFrame.apply() Method
  6. Conclusion
How to Add Empty Column to Pandas DataFrame

Pandas also offer a feature to add one or multiple empty columns to the DataFrame (table). There are different ways available through which we can easily add empty columns in Pandas DataFrame.

We will show in this tutorial how to add one or more empty columns in Pandas DataFrame using various approaches such as using the assignment operator and by using the assign(), insert(), reindex(), and apply() methods. We will also show the implementation of each method to explain the working of each approach briefly.

Add Empty Columns in Pandas DataFrame Using the assignment operator

Using the assignment operator or empty string, we can add empty columns in Pandas DataFrame. And using this approach, the null or NaN values are assigned to any column in the DataFrame.

In the following example, we have created a DataFrame, and then using the assignment operator, we assigned empty string and NaN values to two newly added columns as in the Pandas DataFrame. These columns are Address and Designation. Using the NumPy library, we will import the NaN values into the DataFrame column.

Let’s see how to add the empty columns to the DataFrame in Pandas using the assignment operator or empty string.

Example Code:

import pandas as pd
import numpy as np

company_data = {
    "Employee Name": ["Samreena", "Mirha", "Asif", "Raees"],
    "Employee ID": [101, 102, 103, 104],
}
dataframe = pd.DataFrame(company_data)
print("------------ Original DataFrame --------------\n", dataframe)

# Add empty column using Assignment operator
dataframe["Blank_Column"] = " "
dataframe["Address"] = np.nan
dataframe["Designation"] = None
print("------------ After Adding Empty Columns ---------------\n", dataframe)

Output:

------------ Original DataFrame --------------
   Employee Name  Employee ID
0      Samreena          101
1         Mirha          102
2          Asif          103
3         Raees          104
------------ After Adding Empty Columns ---------------
   Employee Name  Employee ID Designation  Address
0      Samreena          101                  NaN
1         Mirha          102                  NaN
2          Asif          103                  NaN
3         Raees          104                  NaN

Add an Empty Column in Pandas DataFrame Using the DataFrame.assign() Method

The DataFrame.assign() method is used to add one or multiple columns to the DataFrame. Applying the assign() method on a DataFrame returns a new DataFrame after adding the new empty columns in the existing Pandas DataFrame.

Example Code:

import pandas as pd
import numpy as np

company_data = {
    "Employee Name": ["Samreena", "Mirha", "Asif", "Raees"],
    "Employee ID": [101, 102, 103, 104],
}
dataframe1 = pd.DataFrame(company_data)
print("------------ Original DataFrame --------------\n", dataframe1)

# Add empty column into the DataFrame using assign() method
dataframe2 = dataframe1.assign(Designation=" ", Empty_column=np.nan, Address=None)
print("------------ After Adding Empty Columns ---------------\n", dataframe2)

Output:

------------ Original DataFrame --------------
   Employee Name  Employee ID
0      Samreena          101
1         Mirha          102
2          Asif          103
3         Raees          104
------------ After Adding Empty Columns ---------------
   Employee Name  Employee ID Designation  Empty_column Address
0      Samreena          101                       NaN    None
1         Mirha          102                       NaN    None
2          Asif          103                       NaN    None
3         Raees          104                       NaN    None

Add an Empty Column in Pandas DataFrame Using the DataFrame.reindex() Method

The DataFrame.reindex() method assigned NaN values to empty columns in the Pandas DataFrame. This reindex() method takes the list of the existing and newly added columns. Using this method, we can add empty columns at any index location into the DataFrame.

In the following example, we have created a new DataFrame with two-columns names as Employee Name and Employee ID. Later, we used dataframe.reindex() method to add two more new columns, Address and Designation, to the columns list with assigned NaN values.

Example Code:

import pandas as pd
import numpy as np

company_data = {
    "Employee Name": ["Samreena", "Mirha", "Asif", "Raees"],
    "Employee ID": [101, 102, 103, 104],
}
dataframe1 = pd.DataFrame(company_data)
print("------------ Original DataFrame --------------\n", dataframe1)

# Pandas Add empty columns to the DataFrame using reindex() method
dataframe2 = dataframe1.reindex(
    columns=dataframe1.columns.tolist() + ["Designation", "Address"]
)
print("------------ After Adding Empty Columns ---------------\n", dataframe2)

Output:

------------ Original DataFrame --------------
   Employee Name  Employee ID
0      Samreena          101
1         Mirha          102
2          Asif          103
3         Raees          104
------------ After Adding Empty Columns ---------------
   Employee Name  Employee ID  Designation  Address
0      Samreena          101          NaN      NaN
1         Mirha          102          NaN      NaN
2          Asif          103          NaN      NaN
3         Raees          104          NaN      NaN

Add an Empty Column in Pandas DataFrame Using the DataFrame.insert() Method

The DataFrame.insert() method inserts an empty column at any index position (beginning, middle, end, or specified location) in the Pandas DataFrame.

Example Code:

import pandas as pd
import numpy as np

company_data = {
    "Employee Name": ["Samreena", "Mirha", "Asif", "Raees"],
    "Employee ID": [101, 102, 103, 104],
}
dataframe = pd.DataFrame(company_data)
print("------------ Original DataFrame --------------\n", dataframe)

# Pandas Add empty columns to the DataFrame using insert() method
dataframe.insert(1, "Designation", "")
print("------------ After Adding Empty Columns ---------------\n", dataframe)

Output:

------------ Original DataFrame --------------
   Employee Name  Employee ID
0      Samreena          101
1         Mirha          102
2          Asif          103
3         Raees          104
------------ After Adding Empty Columns ---------------
   Employee Name Designation  Employee ID
0      Samreena                      101
1         Mirha                      102
2          Asif                      103
3         Raees                      104

Add an Empty Column in Pandas DataFrame Using the DataFrame.apply() Method

Using the DataFrame.apply() method and Lambda function, we can also add empty columns to the Pandas DataFrame. See the following example to add empty columns to the DataFrame in Pandas using the DataFrame.apply() method.

Example Code:

import pandas as pd
import numpy as np

company_data = {
    "Employee Name": ["Samreena", "Mirha", "Asif", "Raees"],
    "Employee ID": [101, 102, 103, 104],
}
dataframe = pd.DataFrame(company_data)
print("------------ Original DataFrame --------------\n", dataframe)
# Pandas Add empty columns to the DataFrame using apply() method
dataframe["Empty_column"] = dataframe.apply(lambda _: " ", axis=1)
print("------------ After Adding Empty Columns ---------------\n", dataframe)

Output:

------------ Original DataFrame --------------
   Employee Name  Employee ID
0      Samreena          101
1         Mirha          102
2          Asif          103
3         Raees          104
------------ After Adding Empty Columns ---------------
   Employee Name  Employee ID Empty_column
0      Samreena          101             
1         Mirha          102             
2          Asif          103             
3         Raees          104

Conclusion

In this tutorial, we introduced different methods such as assign(), insert(), apply(), and reindex() to add one or multiple empty columns in the Pandas DataFrame. We have also shown how we can add the empty columns to the DataFrame using the assignment operator.

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