How to remove list of words from a list of strings?

Question

list1=['water', 'analog', 'resistance', 'color', 'strap','men', 'stainless', 'timepiece','brown','fast']

list2=['water resistant','water','red strap','digital and analog','analog', 'men', 'stainless steel']

So that output will be

list=['water resistant','red strap','digital and analog','stainless steel']

you only want to remove whole matches? have you tried anything for doing this? — Anand S Kumar, Sep 01 '15 at 06:47
possible duplicate of [Get difference from 2 lists. Python](http://stackoverflow.com/questions/5305164/get-difference-from-2-lists-python) — Andrea Dusza, Sep 01 '15 at 06:53
This is a follow on question from http://stackoverflow.com/q/32241949/4014959 — PM 2Ring, Sep 01 '15 at 09:43

score 4 · Accepted Answer · answered Sep 01 '15 at 06:50

4

You could use set operations:

list(set(list2) - set(list1))

Possible result:

['red strap', 'digital and analog', 'stainless steel', 'water resistant']

If you want to preserve the order you could do the following:

s = set(list1)

[x for x in list2 if x not in s]

Result:

['water resistant', 'red strap', 'digital and analog', 'stainless steel']

answered Sep 01 '15 at 06:50

JuniorCompressor

19,631
4
30
57

As per my view he also want to remove `**` – The6thSense Sep 01 '15 at 07:02
2

@VigneshKalai It was an formatting issue for SO. I'm sure the OP doesn't have any stars in his code. – JuniorCompressor Sep 01 '15 at 07:03

score 1 · Answer 2 · answered Sep 01 '15 at 06:52

You can use set for this. Also with set you won't have any item duplicated.

Here is output from Python Shell

>>> set1 = set(list1)
>>> set2 = set(list2)
>>> set1
set(['brown', 'timepiece', 'color', 'stainless', 'men', 'resistance', 'fast', 'strap', 'water', 'analog'])
>>> set1-set2
set(['brown', 'timepiece', 'color', 'stainless', 'resistance', 'fast', 'strap'])
>>> set2-set1
set(['red strap', '**water resistant**', '**stainless steel**', '**digital and analog**'])
>>> for each in (set2-set1):
        print each

red strap
**water resistant**
**stainless steel**
**digital and analog**
>>> list3 = list(set2-set1)
>>> list3
['red strap', '**water resistant**', '**stainless steel**', '**digital and analog**']

score 1 · Answer 3 · answered Sep 01 '15 at 06:53

1

If you want to

remove * from List2 items
elements not in list1

Try:

>>> list = [x.replace('*', '') for x in list2 if x not in list1]
>>> list
['water resistant', 'red strap', 'digital and analog', 'stainless steel']
>>>

answered Sep 01 '15 at 06:53

Praveen

8,945
4
31
49

kilojoules · Answer 4 · 2015-09-01T18:23:29.677

0

You could do it this way. Iterate through a list of list1 words which are in list2, then use the iterator to remove words. This does not work for repeated words.

>>> for s in [a for a in list1[:] if a in list2[:]]:
...    list2.remove(s)
... 
>>> list2
['water resistant', 'red strap', 'digital and analog', 'stainless steel']

edited Sep 01 '15 at 18:23

answered Sep 01 '15 at 07:17

kilojoules

9,768
18
77
149

While this code may answer the question, providing additional context regarding how and/or why it solves the problem would improve the answer's long-term value. – Peter Brittain Sep 01 '15 at 07:51
What could make those 2 lines of code any clearer? Maybe say that it's a "list comprehension" so that someone who does not recognise the syntax can look it up? But the first time I saw one my thoughts were "awesome" and after playing with it a bit, "does what it says on the tin". – nigel222 Sep 01 '15 at 11:05

How to remove list of words from a list of strings?

4 Answers4