Merging Or Reversing N-grams To A Single String

How do I merge the bigrams below to a single string? _bigrams=['the school', 'school boy', 'boy is', 'is reading'] _split=(' '.join(_bigrams)).split() _newstr=[] _filter=[_newstr.a

Solution 1:

# Multi-for generator expression allows us to create a flat iterable of words
all_words = (word for bigram in _bigrams for word in bigram.split())

defno_runs_of_words(words):
    """Takes an iterable of words and returns one with any runs condensed."""
    prev_word = Nonefor word in words:
        if word != prev_word:
            yield word
        prev_word = word

final_string = ' '.join(no_runs_of_words(all_words))

This takes advantage of generators to lazily evaluate and not keep the entire set of words in memory at the same time until generating the one final string.

Solution 2:

If you really wanted a oneliner, something like this could work:

' '.join(val.split()[0] for val in (_bigrams)) + ' ' +  _bigrams[-1].split()[-1]

Solution 3:

Would this do it? It does simply take the first word up to the last entry

_bigrams=['the school', 'school boy', 'boy is', 'is reading']

clause = [a.split()[0] if a != _bigrams[-1] else a for a in _bigrams]

print' '.join(clause)

Output

the school boy is reading

However, concerning performance probably Amber's solution is a good option