如何在 Python 中区分大小写的同时测试两个字符串是否是字谜？

Question

Okay so I have two functions, one that checks how many times a character appears in a string and another that is supposed to check if the two strings the user inputs are anagrams:

def function_one(s, ch):
    count = 0
    for c in s:
        if c == ch:
            count = count + 1
    return count

def function_two(s, t):
    while len(s) == len(t):
        y = function_one(s, t)
        if y == 0:
            return True
        else:
            return False

Right now function_two will return True if the two strings are anagrams, but it will also return True if they are anagrams but have different letters capitalized, and will return nothing if they aren't anagrams at all. What do I do?

Answer 1

There's a lot of ways of doing this. I think you're complicating things a bit by writing these functions.

The first way of solving this that came in my mind was generating a list with all the letters in each string, sorting them and comparing both lists:

def check_for_anagrams(string1, string2):
    list1 = list(string1.lower())
    list2 = list(string2.lower())
    list1.sort()
    list2.sort()

    return list1 == list2

it might not be the most elegant way to do it, but it's a quick solution. the lower() function turns strings into lowercase the sort() function for lists sorts the list.

if two strings are anagrams, the result of these operations will be two equal lists.

EDIT: Check the possible duplicate thread, there's some nice solutions there!

Answer 2

You can sort out pairs of string that are no anagrams by checking the length of both strings first. In a second stage you can compare the set of characters. This is very fast in Python. In the last stage you have to count the occurences of the single characters in the set to be very sure the strings are anagrams.

CODE

from __future__ import print_function

def isAnagram(s1, s2) :
    s1, s2 = s1.lower(), s2.lower()

    if len(s1) == len(s2) :
        if set(s1) == set(s2) :
            return all([s1.count(c) == s2.count(c) for c in set(s1)])

    return False

string1 = 'Hello'
string2 = 'Hell'    # No anagram of string1
string3 = 'Holle'   # Anagram of string1    

print(isAnagram(string1, string2))
print(isAnagram(string1, string3))

OUTPUT

False
True