基于其他列表列表对列表列表中的项目进行分组

Question

I have the following list of lists:

mylist = [['NNP', 'NN', 'VBZ', 'VBN', 'NNP', 'NNP'],
           ['VB', 'VBN'],
           ['NNP'],
           ['VB', 'NN'],
           ['NN', 'NN']]

I have one more list of lists:

cond = [['NNP', 'NN'], ['VBZ', 'VBN', 'VB']]

I want to group the list of list items in mylist based on the lists in the cond list and get the following output.

out = [['NNP', 'NN'], ['VBZ', 'VBN'], ['NNP', 'NNP'], ['VB', 'VBN'], ['NNP'], ['VB'], ['NN'], ['NN', 'NN']]

The items should be grouped in such a way that the list of list items in mylist should be part of only one list in cond ie, ['NN', 'VBZ'] or ['VBN', 'NNP'] is not expected in output.

This is not a case where I have to split a list when some item is encountered.

I went through many codes where lists are split based on condition, but my problem is different here. Hence it's not a duplicate question.

I don't know the initial approach to take to start coding.

Answer 1

Here's the best I could come up with:

import itertools

mylist = [['NNP', 'NN', 'VBZ', 'VBN', 'NNP', 'NNP'],
           ['VB', 'VBN'],
           ['NNP'],
           ['VB', 'NN'],
           ['NN', 'NN']]

cond = [['NNP', 'NN'], ['VBZ', 'VBN', 'VB']]

out = list()
for sublist in mylist:
    while sublist != []:
        match = list(filter(lambda x: x != [], [list(itertools.takewhile(lambda x: x in condition, sublist)) for condition in cond]))[0]
        out.append(match)
        sublist = sublist[len(match):]

print(out)

First, we iterate through all of the sub-lists. Then we use the itertools method takewhile to construct a list of elements that match any of the conditions in cond . Sometimes there will not be a matching set of elements for the given condition , so we filter out [] results. Then we remove that amount of elements from the front of the list. We add the constructed list to our final list. We then to the takewhile process again until that sublist has been exhausted. We repeat the entire process for every sub-list in mylist .

itertools is a very powerful library in python and you should familiarize yourself with it if you are working with lists or other iterables in python a lot.