How to filter a pandas dataframe by cells that DO NOT contain a substring?

Question

I want to filter a dataframe to find rows which do not contain the string 'site'.

I know how to filter for rows which do contain 'site' but have not been able to get the reverse working. Here is what I have so far:

def rbs(): #removes blocked sites
    frame = fill_rate()
    mask = frame[frame['Media'].str.contains('Site')==True]
    frame = (frame != mask)
    return frame

But this returns an error, of course.

Answer 1

Just do frame[~frame['Media'].str.contains('Site')]

The ~ negates the boolean condition

So your method becomes:

def rbs(): #removes blocked sites
    frame = fill_rate()
    return frame[~frame['Media'].str.contains('Site')]

EDIT

it looks like you have NaN values judging by your errors so you have to filter these out first so your method becomes:

def rbs(): #removes blocked sites
    frame = fill_rate()
    frame = frame[frame['Media'].notnull()]
    return frame[~frame['Media'].str.contains('Site')]

the notnull will filter out the missing values