Suppose I want to find the number of occurrences of something in a pandas dataframe as one number. If I do df.isin(["ABC"]).sum() it gives me a table of all occurrences of "ABC" under each column.
What do I do if I want just one number which is the number of "ABC" entries under column 1?
Moreover, is there code to find entries that have both "ABC" under say column 1 and "DEF" under column 2. even this should just be a single number of entries/rows that have both of these.