CODEWITHSUNDEEP
pythonlistreplace
koogee
koogee

Reputation: 963

replace item in a string if it matches an item in the list

I am trying to remove words from a string if they match a list.

x = "How I Met Your Mother 7x17 (HDTV-LOL) [VTV] - Mon, 20 Feb 2012"

tags = ['HDTV', 'LOL', 'VTV', 'x264', 'DIMENSION', 'XviD', '720P', 'IMMERSE']

print x

for tag in tags:
    if tag in x:
        print x.replace(tag, '')

It produces this output:

How I Met Your Mother 7x17 (HDTV-LOL) [VTV] - Mon, 20 Feb 2012
How I Met Your Mother 7x17 (-LOL) [VTV] - Mon, 20 Feb 2012
How I Met Your Mother 7x17 (HDTV-) [VTV] - Mon, 20 Feb 2012
How I Met Your Mother 7x17 (HDTV-LOL) [] - Mon, 20 Feb 2012

I want it to remove all the words matching the list.

Upvotes: 6

Views: 44187

Answers (4)

eumiro
eumiro

Reputation: 212835

Using your variables tags and x, you can use this:

output = reduce(lambda a,b: a.replace(b, ''), tags, x)

returns:

'How I Met Your Mother 7x17 (-) [] - Mon, 20 Feb 2012'

Upvotes: 4

NPE
NPE

Reputation: 500237

You are not keeping the result of x.replace(). Try the following instead:

for tag in tags:
    x = x.replace(tag, '')
print x

Note that your approach matches any substring, and not just full words. For example, it would remove the LOL in RUN LOLA RUN.

One way to address this would be to enclose each tag in a pair of r'\b' strings, and look for the resulting regular expression. The r'\b' would only match at word boundaries:

for tag in tags:
    x = re.sub(r'\b' + tag + r'\b', '', x)

Upvotes: 17

Marcin
Marcin

Reputation: 49816

(1) x.replace(tag, '') does not modify x, but rather returns a new string with the replacement.

(2) why are you printing on each iteration?

The simplest modification you could do would be:

for tag in tags:
     x = x.replace(tag, '')

Upvotes: 1

Sven Marnach
Sven Marnach

Reputation: 601489

The method str.replace() does not change the string in place -- strings are immutable in Python. You have to bind x to the new string returned by replace() in each iteration:

for tag in tags:
    x = x.replace(tag, "")

Note that the if statement is redundant; str.replace() won't do anything if it doesn't find a match.

Upvotes: 7

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