Tilde sign in python dataframe

Question

I'm new to python/pandas and came across a code snippet.

df = df[~df['InvoiceNo'].str.contains('C')] 

Would be much obliged if I could know what is the tilde sign's usage in this context?

Answer 1

It means bitwise not, inversing boolean mask - Falses to Trues and Trues to Falses.

Sample:

df = pd.DataFrame({'InvoiceNo': ['aaC','ff','lC'],                    'a':[1,2,5]}) print (df)   InvoiceNo  a 0       aaC  1 1        ff  2 2        lC  5  #check if column contains C print (df['InvoiceNo'].str.contains('C')) 0     True 1    False 2     True Name: InvoiceNo, dtype: bool  #inversing mask print (~df['InvoiceNo'].str.contains('C')) 0    False 1     True 2    False Name: InvoiceNo, dtype: bool 

Filter by boolean indexing:

df = df[~df['InvoiceNo'].str.contains('C')] print (df)   InvoiceNo  a 1        ff  2 

So output is all rows of DataFrame, which not contains C in column InvoiceNo.

Answer 2

It's used to invert boolean Series, see pandas-doc.