2018年6月19日

# 求数组元素的和
from functools import reduce


def add(x, y):
    return x + y


s = reduce(add, [1, 3, 5, 7, 9])
print(s)

# 将元素转换为一个数字
from functools import reduce


def f(x, y):
    return x * 10 + y


num = reduce(f, [1, 3, 5, 7, 9])
print(num)


from functools import reduce


def f(x, y):
    return x * 10 + y


def cha_to_num(s):
    digits = {'0': 0, '1': 1, '2': 2, '3': 3, '4': 4, '5': 5,
              '6': 6, '7': 7, '8': 8, '9': 9}
    return digits[s]

# 将字符串转换为整数
num = reduce(f, map(cha_to_num, '13579'))
print(num)

from functools import reduce


def cha_to_num(s):
    digits = {'0': 0, '1': 1, '2': 2, '3': 3, '4': 4, '5': 5,
              '6': 6, '7': 7, '8': 8, '9': 9}
    return digits[s]


num = reduce(lambda x, y: x * 10 + y, map(cha_to_num, '13579'))
print(num)

def normalize(name):
    return name.title()



# 测试:
L1 = ['adam', 'LISA', 'barT']
# 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
L2 = list(map(normalize, L1))
print(L2)

['Adam', 'Lisa', 'Bart']

from functools import reduce


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


print('3 * 5 * 7 * 9 =', prod([3, 5, 7, 9]))
if prod([3, 5, 7, 9]) == 945:
    print('测试成功!')
else:
    print('测试失败!')

3 * 5 * 7 * 9 = 945
测试成功!

# 将浮点数转换为整数
from functools import reduce


def str2float(s):
    # 将浮点数分成整数部分和小数部分
    s_list = s.split('.')
    num1 = reduce(lambda x, y: int(x) * 10 + int(y), s_list[0])
    num2 = reduce(lambda x, y: float(x) * 0.1 + float(y), s_list[-1][::-1])
    return num1 + num2*0.1


print('str2float(\'123.456\') =', str2float('123.456'))
if abs(str2float('123.456') - 123.456) < 0.00001:
    print('测试成功!')
else:
    print('测试失败!')

str2float('123.456') = 123.456
测试成功!

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