How To Find Columns With Nan Values in the Pandas Dataframe – Definitive Guide

There may be some missing values in the dataset that need a cleanup.

You can find columns with NaN values in the pandas Dataframe using df.isna().any() statement.

If You’re in Hurry…

Use the following code to find columns with NaN values.

df.isna().any()

If You Want to Understand Details, Read on…

This tutorial teaches you how to get columns with NaN values in the Pandas dataframe.

The missing values are denoted using Np.NaN or None.

Sample Dataframe

The following dataframe is created with missing values in a few columns.

import pandas as pd

import numpy as np

data = {"product_name":["Keyboard","Mouse", "Monitor", "CPU", "Speakers"],
        "Unit_Price":[500,200, 5000, np.nan, 250.50],
        "No_Of_Units":[5,5, 10, np.nan, 8],
        "Available_Quantity":[5,10,12,15, "Not Available"],
        "Available_Since_Date":['11/5/2021', '4/23/2021', np.nan,'09/18/2021','01/05/2021']
       }

df = pd.DataFrame(data)

df

DataFrame Will Look Like

product_nameUnit_PriceNo_Of_UnitsAvailable_QuantityAvailable_Since_Date
0Keyboard500.05.0511/5/2021
1Mouse200.05.0104/23/2021
2Monitor5000.010.012NaN
3CPUNaNNaN1509/18/2021
4Speakers250.58.0Not Available01/05/2021

Using ISNA

You can find the columns that contain a missing value in any of the cells using df.isna() and any().

  • The isna() method checks if a value is missing in a column
  • The any() function will check if one or more values are missing and returns True or False based on the result.

Code

df.isna().any()

Output

True denotes that the specific columns contain one or more missing values.

    product_name            False
    Unit_Price               True
    No_Of_Units              True
    Available_Quantity      False
    Available_Since_Date     True
    dtype: bool

Using IsNull

Using the isnull() method is an alternate method to check whether the value is missing.

Technically there is no difference between isna and isnull. It is just an alias. It uses the isna() method internally.

Code

df.isnull().any()

Output

    product_name            False
    Unit_Price               True
    No_Of_Units              True
    Available_Quantity      False
    Available_Since_Date     True
    dtype: bool

Get Columns With NaN as List

To get the pandas dataframe columns with NaN as a list,

  • Use the df.columns and df.isna().any() to get the column names
  • Use the tolist() method to convert the names into the list.

Code

df.columns[df.isna().any()].tolist()

Output

The columns with NaN values are returned as a list.

    [‘Unit_Price', 'No_Of_Units', 'Available_Since_Date']

Find Columns With All NaN Values

Some columns in the pandas dataframe might contain missing values in all cells.

To find the columns in which all values are missing, you can use the isna() and the all() function.

Code

df.isna().all()

Output

None of the columns in the sample dataframe contains missing values in all cells. Hence, everything is False in the output.

    product_name            False
    Unit_Price              False
    No_Of_Units             False
    Available_Quantity      False
    Available_Since_Date    False
    dtype: bool

Select Columns With NaN values

To select the columns with NaN values, instead of just selecting the column names, you can pass the list of columns to the df[ ].

In this way, you can see all the values in the columns and identify which cells contain missing values.

Code

df[df.columns[df.isna().any()]]

DataFrame Will Look Like

The columns with NaN values are selected from the dataframe and displayed.

Unit_PriceNo_Of_UnitsAvailable_Since_Date
0500.05.011/5/2021
1200.05.04/23/2021
25000.010.0NaN
3NaNNaN09/18/2021
4250.58.001/05/2021

Additional Resources

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