How to frame two for loops in list comprehension python

Question

I have two lists as below

tags = [u\'man\', u\'you\', u\'are\', u\'awesome\']
entries = [[u\'man\', u\'thats\'],[ u\'right\',u\'awesome\']]

Answer 1

In comprehension, the nested lists iteration should follow the same order than the equivalent imbricated for loops.

To understand, we will take a simple example from NLP. You want to create a list of all words from a list of sentences where each sentence is a list of words.

>>> list_of_sentences = [['The','cat','chases', 'the', 'mouse','.'],['The','dog','barks','.']]
>>> all_words = [word for sentence in list_of_sentences for word in sentence]
>>> all_words
['The', 'cat', 'chases', 'the', 'mouse', '.', 'The', 'dog', 'barks', '.']

To remove the repeated words, you can use a set {} instead of a list []

>>> all_unique_words = list({word for sentence in list_of_sentences for word in sentence}]
>>> all_unique_words
['.', 'dog', 'the', 'chase', 'barks', 'mouse', 'The', 'cat']

or apply list(set(all_words))

>>> all_unique_words = list(set(all_words))
['.', 'dog', 'the', 'chases', 'barks', 'mouse', 'The', 'cat']