如何检查字符串列表中是否存在字符串，包括子字符串？

Question

I have written a function to check for the existence of a value in a list and return True if it exists. It works well for exact matches, but I need for it to return True if the value exists anywhere in the list entry (eg value <= listEntry, I think.) Here is the code I am using for the function:

def isValInLst(val,lst):
    """check to see if val is in lst.  If it doesn't NOT exist (i.e. != 0), 
    return True. Otherwise return false."""
    if lst.count(val) != 0:
        return True
    else:
        print 'val is '+str(val)
        return False

Without looping through the entire character string and/or using RegEx's (unless those are the most efficient), how should I go about this in a pythonic manner?

This is very similar to another SO question , but I need to check for the existence of the ENTIRE val string anywhere in the list. It would also be great to return the index / indices of matches, but I'm sure that's covered elsewhere on Stackoverflow.

Answer 1

If I understood your question then I guess you need any :

return any(val in x for x in lst)

Demo:

>>> lst = ['aaa','dfbbsd','sdfdee']
>>> val = 'bb'
>>> any(val in x  for x in lst)
True
>>> val = "foo"
>>> any(val in x  for x in lst)
False
>>> val = "fde"
>>> any(val in x  for x in lst)
True

Answer 2

There are multiple possibilities to do that. For example:

def valInList1 (val, lst):
    # check `in` for each element in the list
    return any(val in x for x in lst)

def valInList2 (val, lst):
    # join the list to a single string using some character
    # that definitely does not occur in val
    return val in ';;;'.join(lst)

Answer 3

Mostly covered, but if you want to get the index of the matches I would suggest something like this:

indices = [index for index, content in enumerate(input) if substring in content]

if you want to add in the true/false you can still directly use the result from this list comprehension since it will return an empty list if your input doesn't contain the substring which will evaluate to False .

In the terms of your first function:

def isValInLst(val, lst):
    return bool([index for index, content in enumerate(lst) if val in content])

where the bool() just converts the answer into a boolean value, but without the bool this will return a list of all places where the substring appears in the list.