获取字符串中重复出现的字符个数

pythonic

def duplicate_count(s):
    return len([c for c in set(s.lower()) if s.lower().count(c)>1])
    
#test.assert_equals(duplicate_count("abcde"), 0)
#test.assert_equals(duplicate_count(""), 0)
#test.assert_equals(duplicate_count("abcdea"), 1)
#test.assert_equals(duplicate_count("indivisibility"), 1)
#test.assert_equals(duplicate_count("aabbcde"), 2)
#test.assert_equals(duplicate_count("aabbcdeB"), 2)
#test.assert_equals(duplicate_count("Indivisibilities"), 2)

#test.assert_equals(duplicate_count("aabbcdeBBBBBBBBB"), 2) 测试示忽略了这个，如下：
def duplicate_count(text):
    c = 0
    for i in list(set(text)):
        if text.count(i) > 1:
            c = c + 1
    return c