题解 | #表示数值的字符串#

求解步骤：

1.对单独的"."进行处理；

if str == ".":
    return False

2.去除字符串中的空格，组成新字符串(定义filter函数过滤);

def is_space(self, s):
    return s != ' '

str_rm_space = filter(self.is_space, str)
new_str = ""
for s in list(str_rm_space):
    new_str += s

3.字符串中出现两个及以上"."进行处理, 用str.split('.')划分即可判断包含几个".";

# 检查小数点个数
dot_check = new_str.split('.')
if len(dot_check) > 2:
    return False

4.利用正则表达式匹配数字和小数

# 匹配数字和小数，包括小数
if re.match('^(\+|\-|)(\d+)(\.(\d+|))?$', new_str):
    return True
if re.match('^(\+|\-|)(\.\d+)$', new_str):
    return True

5.利用正则表达式匹配科学计数法数字

if re.match('^(\+|\-|)(\d+)(\.\d+)(e|E)(\+|\-|)(\d+)(\.\d+)?$', new_str):
    return True
if re.match('^(\+|\-|)(\d+)(\.)?(e|E)(\-|)(\d+)(\.\d+)?$', new_str):
    return True

整体代码如下

#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param str string字符串 
# @return bool布尔型
#
class Solution:
    def is_space(self, s):
        return s != ' '
        
    def isNumeric(self , str: str) -> bool:
        # write code here
        # 去除空格
        if str == ".":
            return False
        
        str_rm_space = filter(self.is_space, str)
        new_str = ""
        for s in list(str_rm_space):
            new_str += s
        # 检查小数点个数
        dot_check = new_str.split('.')
        if len(dot_check) > 2:
            return False
        import re
        # 匹配数字和小数，包括小数
        if re.match('^(\+|\-|)(\d+)(\.(\d+|))?$', new_str):
            return True
        if re.match('^(\+|\-|)(\.\d+)$', new_str):
            return True
        # 匹配科学计数法数字
        if re.match('^(\+|\-|)(\d+)(\.\d+)(e|E)(\+|\-|)(\d+)(\.\d+)?$', new_str):
            return True
        if re.match('^(\+|\-|)(\d+)(\.)?(e|E)(\-|)(\d+)(\.\d+)?$', new_str):
            return True
        return False