Question

我在python中有一个列表，例如：

        PendingResult<PlaceBuffer> placeResult = Places.GeoDataApi
                .getPlaceById(mGoogleApiClient, placeId);
        placeResult.setResultCallback(mUpdatePlaceDetailsCallback);

我写了这个函数，但这可以用更简单的方式完成吗？

line = ['0', '1', '0', 'R', '1']

Answer 1

你可以把它写成：

def checkCardCommands(line):
    return (len(line) == 5
      and line[0] in ['0', '1']
      and line[1] in ['0', '1', 'None']
      and line[2] in ['0', '1', 'None']
      and line[3] in ['R', 'L']
      and line[4] in ['0', '1'])

Answer 2

def check(line):
    spec = [
        ['0', '1'],
        ['0', '1', 'None'],
        ['0', '1', 'None'],
        ['R', 'L'],
        ['0', '1']
    ]

    return len(line) == len(spec) and all(ln in spc for ln, spc in zip(line, spec))

更短，更具可读性和可维护性。

Answer 3

如果您的验证不太复杂，您可以自己编写一些验证助手：

#!/usr/bin/env python3
# coding: utf-8

def validate(schema, seq):
    """
    Validates a given iterable against a schema. Schema is a list
    of callables, taking a single argument returning `True` if the
    passed value is valid, `False` otherwise.
    """
    if not len(schema) == len(seq):
        raise ValueError('length mismatch')
    for f, item in zip(schema, seq):
        if not f(item):
            raise ValueError('validation failed: %s' % (item))
    return True

if __name__ == '__main__':

    # two validation helper, add more here
    isbool = lambda s: s == '0' or s == '1'
    islr = lambda s: s == 'L' or s == 'R'

    # define a schema
    schema = [isbool, isbool, isbool, islr, isbool]
    # example input
    line = ['0', '1', '0', 'R', '1']

    # this is valid
    validate(schema, ['0', '1', '0', 'R', '1'])

    # ValueError: validation failed: X
    validate(schema, ['0', '1', '0', 'R', 'X'])

    # ValueError: length mismatch
    validate(schema, ['0', '1'])

有关更高级的数据结构架构验证，请查看voluptuous。

尽管有名字，但它是一个Python数据验证库。它主要用于验证作为JSON，YAML等进入Python的数据。

Answer 4

def checkcards():
    return line[0] in ['0','1'] and line[1] in ['0','1','None'] and line[2] in ['0','1','None'] and line[3] in ['R','L'] and line[4] in ['0','1'] and len(line)==5

＆＃39;无＆＃39;是一个字符串，None是一个对象类型。确保你知道你想要使用哪一个。

Answer 5

以下代码将有助于检查动态列表。

line = ['0', '1', '0', 'R', '1']
check_list = [
    ['0', '1'],
    ['0', '1', 'None'],
    ['0', '1', 'None'],
    ['R', 'L'],
    ['0', '1']
]

def check():
  for l, item in enumerate(line):
    if not item in check_list[l]:
        return False
    elif l == 4:
        ### comes here only if each item in line is found in the check_list
        return True

有没有更短的方法来编写这种方法？

5 个答案: