SettingWithCopyWarning even when using .loc[row_indexer,col_indexer] = value

This is one of the lines in my code where I get the SettingWithCopyWarning:

value1['Total Population']=value1['Total Population'].replace(to_replace='*', value=4)

Which I then changed to :

row_index= value1['Total Population']=='*'
value1.loc[row_index,'Total Population'] = 4

This still gives the same warning. How do I get rid of it?

Also, I get the same warning for a convert_objects(convert_numeric=True) function that I’ve used, is there any way to avoid that.

 value1['Total Population'] = value1['Total Population'].astype(str).convert_objects(convert_numeric=True)

This is the warning message that I get:

A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead

See the the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/