Last Updated : 23 Jul, 2025
Cleaning data is an essential step in data analysis. In this guide we will explore different ways to drop empty, null and zero-value columns in a Pandas DataFrame using Python. By the end you'll know how to efficiently clean your dataset using the dropna()
and replace()
methods.
dropna()
The dropna()
function is a powerful method in Pandas that allows us to remove rows or columns containing missing values (NaN
). Depending on the parameters used it can remove rows or columns where at least one value is missing or only those where all values are missing.
Syntax: DataFrameName.dropna(axis=0, how='any', inplace=False)
Parameters:
This is the sample data frame on which we will use to perform different operations.
Python
import numpy as np
import pandas as pd
df = pd.DataFrame({'FirstName': ['Vipul', 'Ashish', 'Milan'],
"Gender": ["", "", ""],
"Age": [0, 0, 0]})
df['Department'] = np.nan
print(df)
Output:
Example 1: Remove All Null Value ColumnsThis method removes columns where all values are NaN
. If a column is completely empty (contains only NaN
values) it is unnecessary for analysis and can be removed using dropna(how='all', axis=1)
.
import numpy as np
import pandas as pd
df = pd.DataFrame({'FirstName': ['Vipul', 'Ashish', 'Milan'],
"Gender": ["", "", ""],
"Age": [0, 0, 0]})
df['Department'] = np.nan
display(df)
df.dropna(how='all', axis=1, inplace=True)
display(df)
Output:
Example 2: Replace Empty Strings with Null and Drop Null ColumnsIf a column contains empty strings we need to replace them with NaN
before dropping the column. Empty strings are not automatically recognized as missing values in Pandas so converting them to NaN
ensures they can be handled correctly. After conversion we use dropna(how='all', axis=1)
to remove columns that are entirely empty.
import numpy as np
import pandas as pd
df = pd.DataFrame({'FirstName': ['Vipul', 'Ashish', 'Milan'],
"Gender": ["", "", ""],
"Age": [0, 0, 0]})
df['Department'] = np.nan
display(df)
nan_value = float("NaN")
df.replace("", nan_value, inplace=True)
df.dropna(how='all', axis=1, inplace=True)
display(df)
Output:
Example 3: Replace Zeros with Null and Drop Null ColumnsIf columns contain only zero values, we convert them to NaN
before dropping them.
import numpy as np
import pandas as pd
df = pd.DataFrame({'FirstName': ['Vipul', 'Ashish', 'Milan'],
"Gender": ["", "", ""],
"Age": [0, 0, 0]})
df['Department'] = np.nan
display(df)
nan_value = float("NaN")
df.replace(0, nan_value, inplace=True)
df.dropna(how='all', axis=1, inplace=True)
display(df)
Output:
Example 4: Replace Both Zeros and Empty Strings with Null and Drop Null ColumnsTo clean a dataset fully we may need to replace both zeros and empty strings.
Python
import numpy as np
import pandas as pd
df = pd.DataFrame({'FirstName': ['Vipul', 'Ashish', 'Milan'],
"Gender": ["", "", ""],
"Age": [0, 0, 0]})
df['Department'] = np.nan
display(df)
nan_value = float("NaN")
df.replace(0, nan_value, inplace=True)
df.replace("", nan_value, inplace=True)
df.dropna(how='all', axis=1, inplace=True)
display(df)
Output:
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