How to check if any value is NaN in a Pandas DataFrame How to check if any value is NaN in a Pandas DataFrame python python

How to check if any value is NaN in a Pandas DataFrame


jwilner's response is spot on. I was exploring to see if there's a faster option, since in my experience, summing flat arrays is (strangely) faster than counting. This code seems faster:

df.isnull().values.any()

enter image description here

import numpy as npimport pandas as pdimport perfplotdef setup(n):    df = pd.DataFrame(np.random.randn(n))    df[df > 0.9] = np.nan    return dfdef isnull_any(df):    return df.isnull().any()def isnull_values_sum(df):    return df.isnull().values.sum() > 0def isnull_sum(df):    return df.isnull().sum() > 0def isnull_values_any(df):    return df.isnull().values.any()perfplot.save(    "out.png",    setup=setup,    kernels=[isnull_any, isnull_values_sum, isnull_sum, isnull_values_any],    n_range=[2 ** k for k in range(25)],)

df.isnull().sum().sum() is a bit slower, but of course, has additional information -- the number of NaNs.


You have a couple of options.

import pandas as pdimport numpy as npdf = pd.DataFrame(np.random.randn(10,6))# Make a few areas have NaN valuesdf.iloc[1:3,1] = np.nandf.iloc[5,3] = np.nandf.iloc[7:9,5] = np.nan

Now the data frame looks something like this:

          0         1         2         3         4         50  0.520113  0.884000  1.260966 -0.236597  0.312972 -0.1962811 -0.837552       NaN  0.143017  0.862355  0.346550  0.8429522 -0.452595       NaN -0.420790  0.456215  1.203459  0.5274253  0.317503 -0.917042  1.780938 -1.584102  0.432745  0.3897974 -0.722852  1.704820 -0.113821 -1.466458  0.083002  0.0117225 -0.622851 -0.251935 -1.498837       NaN  1.098323  0.2738146  0.329585  0.075312 -0.690209 -3.807924  0.489317 -0.8413687 -1.123433 -1.187496  1.868894 -2.046456 -0.949718       NaN8  1.133880 -0.110447  0.050385 -1.158387  0.188222       NaN9 -0.513741  1.196259  0.704537  0.982395 -0.585040 -1.693810
  • Option 1: df.isnull().any().any() - This returns a boolean value

You know of the isnull() which would return a dataframe like this:

       0      1      2      3      4      50  False  False  False  False  False  False1  False   True  False  False  False  False2  False   True  False  False  False  False3  False  False  False  False  False  False4  False  False  False  False  False  False5  False  False  False   True  False  False6  False  False  False  False  False  False7  False  False  False  False  False   True8  False  False  False  False  False   True9  False  False  False  False  False  False

If you make it df.isnull().any(), you can find just the columns that have NaN values:

0    False1     True2    False3     True4    False5     Truedtype: bool

One more .any() will tell you if any of the above are True

> df.isnull().any().any()True
  • Option 2: df.isnull().sum().sum() - This returns an integer of the total number of NaN values:

This operates the same way as the .any().any() does, by first giving a summation of the number of NaN values in a column, then the summation of those values:

df.isnull().sum()0    01    22    03    14    05    2dtype: int64

Finally, to get the total number of NaN values in the DataFrame:

df.isnull().sum().sum()5


To find out which rows have NaNs in a specific column:

nan_rows = df[df['name column'].isnull()]


matomo