I have data of the following structure
I want to check how many values of the column "Item_Identifier" are missing in the test data.
I have already got a list of unique "Item_Identifier" from the test by
item_ids_in_test = test.Item_Identifier.unique()
Surely I can run loops and check but the dataset is large , it will take time and I am looking for a better way , if pandas provide it?