CODEWITHSUNDEEP
pythonstringpython-2.7
Apollo
Apollo

Reputation: 9054

find() with multiple substrings - Python

How would I find the first occurrence of either the character e or o?

I want to do something like this:

my_string = "Hello World"
x = my_string.find('e' or 'o',my_string)
print x # 1

Upvotes: 2

Views: 1315

Answers (3)

Hackaholic
Hackaholic

Reputation: 19733

you can use collections.defaultdict:

>>> import collections
>>> my_dict = collections.defaultdict(list)
>>> for i,x in enumerate("hello world"):
...     if x in "eo":
...         my_dict[x].append(i)
... 
>>> my_dict
defaultdict(<type 'list'>, {'e': [1], 'o': [4, 7]})
>>> my_dict['e'][0]     # 1st  'e'
1
>>> my_dict['o'][0]     # 1st 'o'
4

Upvotes: 0

user554546
user554546

Reputation:

Alternatively, you could do a find on each character and then take the minimum of all the results (throwing away the -1s unless all of them are -1):

def first_index(string, search_chars):

    finds = [string.find(c) for c in search_chars]
    finds = [x for x in finds if x >= 0]

    if finds:
        return min(finds)
    else:
        return -1

This yields:

>>> first_index("Hello World", "eo")
1
>>> first_index("Hello World", "xyz")
-1

Upvotes: 0

thefourtheye
thefourtheye

Reputation: 239443

Use enumerate function with a generator expression, like this

>>> next(idx for idx, char in enumerate("Hello World") if char in 'eo')
1

It will give the index of the first character which is either e or o.

Note: It will fail if the characters are not there in the string. So, you can optionally pass the default value, like this

>>> next((idx for idx, char in enumerate("Hello World") if char in 'eo'), None)
1
>>> next((idx for idx, char in enumerate("Hi") if char in 'eo'), None)
None

Upvotes: 1

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