CODEWITHSUNDEEP
pythonpandasnumpydataframe
Hanuman95
Hanuman95

Reputation: 103

How to check for null elements in a list in a dataframe in np.where()?

My dataframe, df:

Col_A Col_B
Apple [1,2,3]
Banana [1,null,4]
Orange [6,null,null]

The nulls are represented as np.nans in the dataframe. How can I check if all the values in each row of Col_B are null?
This is my np.where:

np.where(pd.isnull(df[Col_B]).all(), "Fail", "Pass")

However, I get a truth value is ambiguous even though I have a ".all()" there. Any way to get around this issue?

Upvotes: 2

Views: 1228

Answers (1)

Whitewater
Whitewater

Reputation: 317

I don't believe you need to use np.where() here. You can try it two other ways:

df['one_bad'] = df['Col_B'].apply(lambda x: np.nan in x)

will return True if there's at least one np.nan in the list. But you can use np.isnan().all() to check if all values are np.nan.

df['all_bad'] = df['Col_B'].apply(lambda x: np.isnan(x).all())

will return True if all the values in the list are np.nan and False otherwise.

Upvotes: 2

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