I have a list in python which looks like this:
['x','x','x','x','P','x','x','N','P','N','x','x','x','N','P','x','x,'x,','x','x','x','N','x,'x','P','N','x','x','x'....]
I need to process the list in some way such that I return individual sequences of P and N. In the above case I need to return:
[['P'],['N','P','N'],['N','P'],['N'],['P','N'].....]
I have looked at itertools but have not found anything that can do this. I have a lot of lists to process in this way so efficiency is also important.
You can do it using itertools.groupby:
from itertools import groupby
data = ['x','x','x','x','P','x','x','N','P','N','x','x','x','N',
'P','x','x','x','x','x','x','N','x','x','P','N','x','x','x']
out = list(list(g) for k, g in groupby(data, lambda item: item in {'N', 'P'}) if k)
print(out)
# [['P'], ['N', 'P', 'N'], ['N', 'P'], ['N'], ['P', 'N']]
We group according to item in {'N', 'P'}, and keep only the groups for which this is True.