新内容记录:
1.js替换输入的中文逗号为英文逗号
onkeyup='javascript:this.value=this.value.replace(",",",");
2.快速的ip查询库:ip2Region
https://gitee.com/lionsoul/ip2region
3.Counter(计数器):用于追踪值的出现次数
#统计词频 colors = ['red', 'blue', 'red', 'green', 'blue', 'blue'] result = {} for color in colors: if result.get(color)==None: result[color]=1 else: result[color]+=1 print (result) #{'red': 2, 'blue': 3, 'green': 1}
下面我们看用Counter怎么实现:
from collections import Counter colors = ['red', 'blue', 'red', 'green', 'blue', 'blue'] c = Counter(colors) print (dict(c))
显然代码更加简单了,也更容易读和维护了
4.使用sorted函数
用 operator 函数进行多级排序
from operator import itemgetter, attrgetter students = [('john', 'A', 15), ('jane', 'B', 12), ('dave', 'B', 10),] sorted(students, key=itemgetter(2)) sorted(students, key=itemgetter(1,2)) # sort by grade then by age [('john', 'A', 15), ('dave', 'B', 10), ('jane', 'B', 12)]