CODEWITHSUNDEEP
pythonstring
marc
marc

Reputation: 2187

Way to check that string contains two of the same characters?

Lets say I have:

str = "Hello! My name is Barney!"

Is there a one or two line method to check if this string contains two !?

Upvotes: 11

Views: 37721

Answers (5)

lazzzis
lazzzis

Reputation: 141

Except str.count, I think filter is also a feasible way:

Python 2:

>>> len(filter(lambda x: x == '!', "Hello! My name is Barney!"))
2

Python 3:

>>> len(list(filter(lambda x: x == '!', "Hello! My name is Barney!")))
2

Upvotes: 0

user6537920
user6537920

Reputation:

Use

str.count("!")

So:

if str.count("!") == 2:
   return True

Upvotes: 1

MakeCents
MakeCents

Reputation: 764

There are a bunch of one liner ways to find the number of characters in a string:

string  = "Hello! My name is Barney!"

Ways:

string.count('!') == 2 #best way

or

len([x for x in string if x == '!']) == 2 #len of compresion with if

or

len(string)-len(string.replace('!','')) == 2 #len of string - len of string w/o character

or

string[string.find('!')+1:].find('!')>0 #find it, and find it again, at least twice

count is the best, but I love to think of other ways, because I sometimes find redundant code/variables that way, depending on what you are doing of course. Say if you already have the len of the string and the len of the string with the characters replaced in variables, for some other reason, then you can simply subtract those variables. Probably not the case, but something to think about.

Upvotes: 0

user2555451
user2555451

Reputation:

Yes, you can get the solution in one line easily with the count method of a string:

>>> # I named it 'mystr' because it is a bad practice to name a variable 'str'
>>> # Doing so overrides the built-in
>>> mystr = "Hello! My name is Barney!"
>>> mystr.count("!")
2
>>> if mystr.count("!") == 2:
...     print True
...
True
>>>
>>> # Just to explain further
>>> help(str.count)
Help on method_descriptor:

count(...)
    S.count(sub[, start[, end]]) -> int

    Return the number of non-overlapping occurrences of substring sub in
    string S[start:end].  Optional arguments start and end are
    interpreted as in slice notation.

>>>

Upvotes: 20

falsetru
falsetru

Reputation: 369044

Use str.count method:

>>> s = "Hello! My name is Barney!"
>>> s.count('!')
2

BTW, don't use str as variable name. It shadows builtin str function.

Upvotes: 4

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