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交作业

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chengww5217

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1.利用map()函数,把用户输入的不规范的英文名字,变为首字母大写,其他小写的规范名字。输入:['adam', 'LISA', 'barT'],输出:['Adam', 'Lisa', 'Bart']:

# -*- coding: utf-8 -*-
def normalize(name):
    return name[:1].upper() + name[1:].lower()
    # return name.capitalize()

2.Python提供的sum()函数可以接受一个list并求和,请编写一个prod()函数,可以接受一个list并利用reduce()求积:

# -*- coding: utf-8 -*-
from functools import reduce
def prod(L):
    return reduce(fn, L)

def fn(x, y):
    return x*y

# def prod(L):
#     return reduce(lambda x, y: x*y, L)

3.利用map和reduce编写一个str2float函数,把字符串'123.456'转换成浮点数123.456:

# -*- coding: utf-8 -*-
from functools import reduce

def str2float(s):
    digits = {'0' : 0, '1' : 1, '2' : 2, '3' : 3, '4' : 4, '5' : 5, '6' : 6, '7' : 7, '8' : 8, '9' : 9, '.' : '.'}
    aMap = map(lambda n : digits[n], s)
    aList = list(aMap)
    indexPoint = -1
    try:
        indexPoint = s.index('.')
        aList.pop(indexPoint)
    except ValueError:
        pass
    aInt = reduce(lambda x, y: 10*x + y, aList)
    if indexPoint < 0:
        return aInt
    aFloat = aInt / (10 ** (len(s) - 1 - indexPoint))
    return aFloat

print('str2float(\'123456\') =', str2float('123456'))

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