CODEWITHSUNDEEP
python
Sharon Watinsan
Sharon Watinsan

Reputation: 9840

Searching for a sequence in a text

I have run into a logic problem.

I have a string declared as follows:

fruits = "banana grapes apple"
vegetables = "potatoes cucumber carrot"

Now there are some text sentences, and i have to search for the word that is in front of the text format <vegetables> <fruits>

I ate carrot grapes ice cream for dessert.

Answer : ate

Dad and mom brought banana cucumber and milk.

Answer : brought

What i was thinking is to split the sentence and put it in an array, and then look for the sequence, i was able to break the sentence but matching the sequence is a problem.

wd = sentence.split(' ')
for x in wd.strip().split():
# now i will have to look for the sequence

Now, i will have to look for the text that is in front of the text format

Upvotes: 1

Views: 103

Answers (3)

Ashwini Chaudhary
Ashwini Chaudhary

Reputation: 250881

You're using wrong data-structures here, convert fruits and vegetables to sets. Then the problem is very easy to solve:

>>> fruits = set("banana grapes apple".split())
>>> vegetables = set("potatoes cucumber carrot".split())
>>> fruits_vegs = fruits | vegetables                  
>>> from string import punctuation
def solve(text):                                   
    spl = text.split()
    #use itertools.izip and iterators for memory efficiency.
    for x, y in zip(spl, spl[1:]): 
        #strip off punctuation marks
        x,y = x.translate(None, punctuation), y.translate(None, punctuation)
        if y in fruits_vegs and x not in fruits_vegs:
            return x
...         
>>> solve('I ate carrot grapes ice cream for dessert.')
'ate'
>>> solve('Dad and mom brought banana cucumber and milk.')
'brought'
>>> solve('banana cucumber and carrot.')
'and'

Upvotes: 2

Brionius
Brionius

Reputation: 14098

fruits = "banana grapes apple".split(" ")
vegetables = "potatoes cucumber carrot".split(" ")

sentence = 'Dad and mom brought banana cucumber and milk.'

wd = sentence.split(' ')
for i, x in enumerate(wd):
    if (x in fruits or x in vegetables) and i > 0:
        print wd[i-1]
        break

Upvotes: 1

nneonneo
nneonneo

Reputation: 179402

You can do this with regex:

def to_group(l):
    ''' make a regex group from a list of space-separated strings '''
    return '(?:%s)' % ('|'.join(l.split()))

pattern = r'(\w+) %s %s' % (to_group(vegetables), to_group(fruits))
print re.findall(pattern, string)

Upvotes: 1

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