Pandas - updating the original dataframe with sub selects

[Ecniv]

Hi

I have a dataframe with the follwoing columns

source	date	host	tag	adreq	adimpr	revenue	Device	deleteme

Now some of the rows have things I do not want to see, but I do not want to delete.
How do I update the dataframe.

I tried the following - but this gives a warning about updating a slice

tdf = self.dfDemands[ (self.dfDemands.deleteme == False) & (self.dfDemands.source == 'thesource') & (self.dfDemands.host == 'nameofahost') ]
tdf['deleteme'] = True
self.dfDemands.update( tdf )

Also tried

self.dfDemands['deleteme'] = (self.dfDemands.deleteme == False) & (self.dfDemands.source == 'Source') & (self.dfDemands.host == 'nameofahost')

Which although doesn't appear to error - doesn't up date either

Must be something simple... Any pointers please?

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link to settingwithwarning
Nevermind, the link helped and I think it is working as required now :)