Python-练习题代码记录

 自己实现一些内建函数的部分功能

def my_abs(num):
    if not isinstance(num,(int, float)):
        print('false')
        return False
    if num < 0:
        num *= -1
    return num
print(my_abs(2))
print(my_abs(-2))
my_abs('tes')

def my_sum(lst):
    sum = 0
    if not isinstance(lst, list):return lst
    for item in lst:
        if isinstance(item,(int,float)):
            sum += item
    return sum
print(my_sum([1,2,'12',3]))

def my_max(seq):
    max_seq = None
    if not isinstance(seq,(list, tuple)):return max_seq
    if len(seq) == 0:return max_seq
    max_seq = seq[0]
    for item in seq:
        if not isinstance(item,(int, float)):continue
        elif item > max_seq:
            max_seq = item
    return max_seq

print(my_max([1,2,3,'4']))

def my_min(seq):
    min_seq = None
    if not isinstance(seq, (list, tuple)): return min_seq
    if len(seq) == 0: return min_seq
    min_seq = seq[0]
    for item in seq:
        if not isinstance(item, (int, float)):
            continue
        elif item < min_seq:
            min_seq = item
    return min_seq

print(my_min([1, 2, 3, '4']))

str_int_dic = {
    '0': 0,
    '1': 1,
    '2': 2,
    '3': 3,
    '4': 4,
    '5': 5,
    '6': 6,
    '7': 7,
    '8': 8,
    '9': 9
}

def my_int(string):
    res = 0
    for item in string:
        int_value = str_int_dic[item]
        res = res*10 + int_value
    return res

print(my_int('456'))

int_str_dict = {
    0: '0',
    1: '1',
    2: '2',
    3: '3',
    4: '4',
    5: '5',
    6: '6',
    7: '7',
    8: '8',
    9: '9',
}

def my_str(intnum):
    if intnum == 0:
        return '0'

    lst = []
    is_positive = True
    if intnum < 0:
        is_positive = False
        intnum = abs(intnum)

    while intnum:
        number = intnum % 10
        intnum //= 10
        str_number = chr(number+48)
        lst.append(str_number)

    if not is_positive:
        lst.append('-')
    lst = lst[::-1]
    return ''.join(lst)

print(my_str(9))
print(my_str(-123))

def my_float(string):
    arrs = string.split('.')
    int_value = my_int(arrs[0])
    float_value = my_int(arrs[1])
    while float_value > 1:
        float_value *= 0.1
    return int_value + float_value

print(my_float("42.0"))
print(type(my_float("42.22")))


from collections import Iterable

def my_len(obj):
    if not isinstance(obj, Iterable):return None

    length = 0
    for item in obj:
        length += 1
    return length

print(my_len([1,2,]))
print(my_len((1,2)))
print(my_len({'a':2}))

def my_enumerate(lst):
    for i in range(my_len(lst)):
        yield i, lst[i]

lst = ['a', 'b', 'c']
for index,item in my_enumerate(lst):
    print(index, item)


def my_all(lst):
    for item in lst:
        if not item:
            return False
    return True
lst1 = [True, False, True]
print(my_all(lst1))
print(all(lst1))

def my_any(lst):
    for item in lst:
        if item:
            return True
    return False
print(my_any(lst))