Ebay Car Sales: Exploring the date columns

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https://app.dataquest.io/m/294/guided-project%3A-exploring-ebay-car-sales-data/5/exploring-the-date-columns

Hi everyone! Can someone help me out please? I don’t understand why we have to specify the dropna = False part in

Series.value_counts(normalize=True, dropna=False)

when date_crawled , ad_created , and last_seen have no null values.

By default this parameter is set to True. Usually you do not know which columns have NaN values and how many. Therefore not to loose same valuable data, you may want to turn it to False.

Also usually it is good idea to check how many NaNs your data contain. You can do it with .isna().sum():

> s = pd.Series([1,2,3, np.nan, np.nan])
> s.isna().sum()
2
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Thank you for the reply! I just don’t understand why we got told to specify it using this example

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I had the same doubt! It’s unnecessary. Thanks for sharing your concern, though.