python - 将字典的一部分与副本合并

Question

我是 Python 的初学者，所以请多多包涵。

我有一个看起来像这样的字典列表:

list = [
    {
        "name": "Bus 60",
        "direction": "City",
        "timeLeft": "1",
        "timeNext": ""
    },
    {
        "name": "Bus 60",
        "direction": "City",
        "timeLeft": "3",
        "timeNext": ""
    },
    {
        "name": "Bus 1",
        "direction": "Some Place",
        "timeLeft": "15",
        "timeNext": ""
    },
    {
        "name": "Bus 1",
        "direction": "Some Place",
        "timeLeft": "30",
        "timeNext": ""
    },
    {
        "name": "Bus 1",
        "direction": "That other place",
        "timeLeft": "5",
        "timeNext": ""
    },
]

我希望根据“名称”和“方向”合并这两个，如下所示:

new_list = [
    {
        "name": "Bus 60",
        "direction": "City",
        "timeLeft": "1",
        "timeNext": "3"
    },
    {
        "name": "Bus 1",
        "direction": "Some Place",
        "timeLeft": "15",
        "timeNext": "30"
    },
    {
        "name": "Bus 1",
        "direction": "That other place",
        "timeLeft": "5",
        "timeNext": ""
    },
]

我如何才能实现这一目标并了解它的实际工作原理？我尝试了很多带有循环的解决方案，但它们最终都以大量重复或错误合并告终。

编辑:每个名称和方向的重复项永远不会超过一个。

编辑 2:这是我的完整方法:

@APP.route('/api/vasttrafik/departures', methods=['POST'])
def get_departures():
    """ Departures """
    APP.logger.info('get_departures():')

    data = request.get_json()
    id_number = data['id']
    current_date = date.today().strftime('%Y-%m-%d')
    current_time = datetime.now().strftime('%H:%M')
    # time_span = data['']
    access_token = request.headers['access_token']

    url = 'https://api.vasttrafik.se/bin/rest.exe/v2/departureBoard?id='\
        + id_number + '&date=' + current_date + '&time=' + current_time +\
        '&format=json&timeSpan=90&maxDeparturesPerLine=2&needJourneyDetail=0'
    headers = {'Authorization': 'Bearer ' + access_token}
    req = requests.get(url, headers=headers)
    json = req.json()
    departure_board = json['DepartureBoard']
    if 'error' in departure_board:
        raise NotFoundException('Did not find anything')
    departures = departure_board['Departure']

    def departures_model(item):

        def get_key_value(key):
            return item[key] if key in item else ''

        is_live = 'rtTime' in item
        if is_live:
            current_time = get_key_value('rtTime')
            current_date = get_key_value('rtDate')
        else:
            current_time = get_key_value('time')
            current_date = get_key_value('date')

        direction = get_key_value('direction')
        via = ''
        if 'via' in direction:
            direction, via = direction.split('via')

        time_departure = datetime.strptime(current_date + ' ' + current_time, '%Y-%m-%d %H:%M')
        time_now = datetime.now()
        diff = time_departure - time_now
        if time_now >= time_departure:
            minutes_left = 0
        else:
            minutes_left = math.floor(((diff).seconds) / 60)
        clock_left = item['rtTime'] if is_live else item['time']

        return dict({
            'accessibility': get_key_value('accessibility'),
            'bgColor': get_key_value('bgColor'),
            'clockLeft': clock_left,
            'clockNext': '',
            'timeLeft': int(minutes_left),
            'timeNext': '',
            'direction': direction.strip(),
            'via': 'via ' + via.strip() if via != '' else via,
            'name': get_key_value('name'),
            'sname': get_key_value('sname'),
            'type': get_key_value('type'),
            'time': get_key_value('time'),
            'date': get_key_value('date'),
            'journeyid': get_key_value('journeyid'),
            'track': get_key_value('track'),
            'fgColor': get_key_value('fgColor'),
            'isLive': is_live,
            'night': 'night' in item,
        })

    mapped_departures = list(map(departures_model, departures))

    def key(bus):
        return bus["name"], bus["direction"]

    def merge_busses(ls):
        for (name, direction), busses in groupby(ls, key):
            busses = list(busses)
            times = [bus["timeLeft"] for bus in busses]
            yield {
                **busses[0],
                "timeLeft": min(times, key=int),
                "timeNext": max(times, key=int),
            }

    merge_departures = list(merge_busses(mapped_departures))

    return jsonify({
        'departures': merge_departures,
    })

编辑 3:我刚刚发现为什么 L3viathan 和 Patrick Artner 的解决方案不起作用。只有事先对总线列表进行排序，它们才有效。所以我想 groupby 需要相邻的字典。

Answer 1

这是我的解决方案:我们使用 itertools.groupby 按名称-方向组合对总线进行分组，然后生成字典，其中 timeLeft 是其中最小的分钟数总线，timeNext 是一个空字符串(如果我们只看到一辆公交车)或这些公交车内的最大分钟数。

from itertools import groupby

def key(bus):
    return bus["name"], bus["direction"]

def merge_busses(ls):
    for (name, direction), busses in groupby(sorted(ls, key=key), key):
        busses = list(busses)
        times = [bus["timeLeft"] for bus in busses]
        yield {
            **busses[0],
            "timeLeft": min(times, key=int),
            "timeNext": "" if len(times) == 1 else max(times, key=int),
        }

像这样使用它:

new_list = list(merge_busses(mylist))

在你的例子中使用，这会产生:

[
    {
        "name": "Bus 60",
        "direction": "City",
        "timeLeft": "1",
        "timeNext": "3"
    },
    {
        "name": "Bus 1",
        "direction": "Some Place",
        "timeLeft": "15",
        "timeNext": "30"
    },
    {
        "name": "Bus 1",
        "direction": "That other place",
        "timeLeft": "5",
        "timeNext": ""
    }
]