Python3如何从字符串中提取各类十进制数并转换为float类型

实现逻辑 #

使用正则匹配定位字符串中所有符合要求的十进制数，过滤掉$符号后转换为float类型即可，无需额外处理前导零，Python的float转换会自动保留对应数值。

修改后完整代码 #

import re

def mode(x):
    if len(x) == 0:
        return 0
    else:
        theDictionary = {}
        for number in x:
            count = theDictionary.get(number, None)
            if count == None:
                theDictionary[number] = 1
            else:
                theDictionary[number] = count + 1
        theMaximum = max(theDictionary.values())
        for key in theDictionary:
            if theDictionary[key] == theMaximum:
                print("Mode: ", key)
                return key


def median(x):
    if len(x) == 0:
        return 0
    else:
        x.sort()
        midpoint = len(x) // 2
        print("Median: ", end=" ")
        if len(x) % 2 == 1:
            print(x[midpoint])
            med = x[midpoint]
        else:
            print((x[midpoint] + x[midpoint - 1]) / 2)
            med = (x[midpoint] + x[midpoint - 1]) / 2
        return med


def mean(x):
    if len(x) == 0:
        return 0
    else:
        theSum = 0.0
        for number in x:
            theSum += number
        average = theSum / len(x)
        print("Mean: ", average)
        return average


def main():
    print ("Enter a list of numbers or enter to quit: ")
    numbers = input()
    if numbers == "":
        return 0
    else:
        # 核心修改：正则提取所有符合要求的数字
        pattern = r'\$?\d+\.?\d*'
        matches = re.findall(pattern, numbers)
        lyst = [float(match.lstrip('$')) for match in matches]
        print("List: ", lyst)
        mode(lyst)
        median(lyst)
        mean(lyst)
        main()

if __name__ == "__main__":
    main()

适配验证 #

输入样例字符串 5, 7 83 100, $5.07, and 7.834 时，提取得到的数字列表为 [5.0, 7.0, 83.0, 100.0, 5.07, 7.834]，完全覆盖需求场景：

• 支持整数、小数提取
• 支持带$前缀的金额提取
• 自动忽略字符串中的标点、普通文本内容
• 带前导零的数值转换后精度保留正常

内容的提问来源于stack exchange，提问作者David G