vaylain vaylain - 1 year ago 117
Python Question

How to find an exact sequence of words in lists using Python 3?

I am coding in Python 3 on a Windows platform.

I am making a function that will pass in a user's inputted sentence which my function will then

and make it a list of each word that was in their original sentence.

My function will also pass in a predefined list of word patterns that my function will be watching for as a match on the exact sequence of words appearing in the user's sentence.

Now just so this is clear, I already can use
to find where the exact words are matches but I am looking for an exact sequence of words.

For instance if my user inputs:
"I love hairy cats"
, and the predefined list of key words is something like this:
["I love", "hairy cats", "I love cats", "love hair"]
, my function should only indicate
"I love"
"hairy cats"
as these two matched the specified sequence of words as they appeared in the predefined lists.

Here is my code thus far:

def parse_text(message, keywords):
newList = []
Message = message.split()
Keywords = keywords # Keywords need to be a list type
setMessage = set(word for word in Message)
setKeywords = set(word for word in Keywords)
newList = setMessage.intersection(setKeywords)

return newList

This works perfectly so far only if my keywords list contains only single words. My issue is when I try to make my list with multiple words to denote the sequence.

If my user's original message is:

message = "Hello world, yes and no"

keywords = ["help", "Hello", "yes", "so"] # this works, intersec "Hello" and "yes"

keywords = ["help me", "Hello mom", "yes and no", "so"] # this does not work, just returns empty "set()"

Any ideas of how I can make adjustments to my function to check my user's original sentence for a specific sequence of words as they appear my keyword list?

Answer Source

Why use sets at all? This is a pretty straightforward string operation:

def parse_text(message, keywords):
     newList = []
     for keyword in keywords:
         if keyword in message:
     return newList

or, using list comprehensions for more succinctness:

def parse_text(message, keywords):
    return [keyword for keyword in keywords if keyword in message]
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