python把str轉換為int

def str2int(s):
    def fn(x,y):
        return x+y
    def char2num(s):
        return {'0':0,'1':1,'2':2,'3':3,'4':4,'5':5,'6':6,'7':7,'8':8,'9':9}[s]
    return reduce(fn,map(char2num,s))

print(str2int('2468'))