Count all letters,digits,and special symbols from a given string

要统计给定字符串中的字母、数字和特殊字符，你可以使用Python的内置函数。这里有两个不同的方法：

1. **计数特定类型的字符**[^1]:
使用`str.count()`函数可以计算每个字符（包括字母、数字和特殊字符）在字符串中出现的次数。如果只关心字母、数字和特殊字符，你需要遍历字符串并检查字符的类别。

def count_special_chars(s):
    letter_count = sum(c.isalnum() for c in s)
    digit_count = sum(c.isdigit() for c in s)
    special_char_count = len(s) - letter_count - digit_count
    return letter_count, digit_count, special_char_count

# 示例
input_string = "Hello, World! 123"
letters, digits, specials = count_special_chars(input_string)
print(f"Letters: {letters}, Digits: {digits}, Specials: {specials}")

2. **分割字符串并计数**：
另一种方式是先通过分隔符（默认为空格）将字符串分割成子串，然后对每个子串进行计数。这种方法适用于你想要知道整个字符串中有多少组特定模式的情况。

def count_by_group(s, delimiter=None, group_type=str.isalnum):
    if delimiter is None:
        delimiter = " "
    substrings = s.split(delimiter)
    counts = {c: sum(1 for _ in filter(group_type, sub)) for c in set(substrings)}
    return counts

# 示例
input_string = "Hello, World! 123"
counts = count_by_group(input_string)
for char, count in counts.items():
    print(f"{char}: {count}")