python健壮地将任何带有单位的字符串转换为浮点型

def convert_to_float(string):
    units = {
        'K': 10**3,
        'M': 10**6,
        'G': 10**9,
        'T': 10**12,
        'P': 10**15,
        'E': 10**18,
    }
    
    try:
        value = float(string[:-1])
        unit = string[-1].upper()
        
        if unit in units:
            return value * units[unit]
        else:
            return value
    except ValueError:
        return None

# 示例用法
print(convert_to_float('1.5K'))  # 输出: 1500.0
print(convert_to_float('2.3M'))  # 输出: 2300000.0
print(convert_to_float('100'))   # 输出: 100.0
print(convert_to_float('1.2X'))  # 输出: None