Check if string contains more than one element from array in Python

Question

I'm using regular expression in my project, and have an array like this :

myArray = [
    r"right",
    r"left",
    r"front",
    r"back"
]

Now I want to check if the string, for example

message = "right left front back"

has more than one match in this array, my purpose here is to have an if being true only if there is only one word matching one of the array.

I tried a lot of things, like this one

if any(x in str for x in a):

but I never make it work with a limited amount.

How about matches = [x for x in a if x in str]. You could then check the number of matches with len(matches). — zondo
– zondo, Commented Mar 3, 2016 at 18:41
Possible duplicate of Python: how to determine if a list of words exist in a string — Michal Frystacky
– Michal Frystacky, Commented Mar 3, 2016 at 18:41
@Michal Frystacky Didn't came across that one, even if i checked a lot before, stackoverflow is so huge ! thanks ! — ThaoD5
– ThaoD5, Commented Mar 3, 2016 at 18:50

Tomalak · Accepted Answer · 2016-03-03 18:41:56Z

3

matches = [a for a in myArray if a in myStr]

Now check the len() of matches.

answered Mar 3, 2016 at 18:41

Tomalak

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Comments

Bhargav Rao · Accepted Answer · 2016-03-03 18:41:09Z

3

You can use sum here. The trick here is that True is calculated as 1 while finding the sum. Hence you can utilize the in directly.

>>> sum(x in message for x in myArray)
4
>>> sum(x in message for x in myArray) == 1
False

if clause can look like

>>> if(sum(x in message for x in myArray) == 1):
...     print("Only one match")
... else:
...     print("Many matches")
... 
Many matches

answered Mar 3, 2016 at 18:41

Bhargav Rao

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1 Comment

ThaoD5 Over a year ago

Thanks, exactly what i needed, with the if statement example, perfect ;-)

pp_ · Accepted Answer · 2016-03-03 18:54:55Z

2

any(x in message for x in myArray)

Evaluates to True if at least one string in myArray is found in message.

sum(x in message for x in myArray) == 1

Evaluates to True if exactly one string in myArray is found in message.

edited Mar 3, 2016 at 18:54

answered Mar 3, 2016 at 18:48

pp_

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Comments

MaxU - stand with Ukraine · Accepted Answer · 2016-03-03 19:10:28Z

2

If you are looking for one of the fastest ways to do it use intersections of sets:

mySet  = set(['right', 'left', 'front', 'back'])
message = 'right up down left'

if len(mySet & set(message.split())) > 1:
    print('YES')

edited Mar 3, 2016 at 19:10

answered Mar 3, 2016 at 18:58

MaxU - stand with Ukraine

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