Question

有一个名为cleaned_trips的对象，它是一个行程列表，它的字典具有诸如trip_distance，pickup_latitude，pickup_longitude之类的键。现在，从此列表中仅获得键pickup_latitude和pickup_longitude，并返回标记对象，其位置格式为[pickup_latitude, pickup_longitude]。这是我尝试过的方法，但始终附加相同的位置。

cleaned_trips = [{'trip_distance': 18.38,
                  'pickup_latitude': 40.64499,
                  'pickup_longitude': -73.78115},
                 {'trip_distance': 1.3,
                  'pickup_latitude': 40.766931,
                  'pickup_longitude': -73.982098},
                 {'trip_distance': 4.5,
                  'pickup_latitude': 40.77773,
                  'pickup_longitude': -73.951902},
                 {'trip_distance': 2.4,
                  'pickup_latitude': 40.795678,
                  'pickup_longitude': -73.971049}]


def location(trip):
    latlng = [trip['pickup_latitude'], trip['pickup_longitude']]
    return latlng


def markers_from_trips(trips):
    new_list = []
    marker = {}
    for trip in trips:

        for key in trip:
            marker['location'] = location(trip)
            new_list.append(marker)
    return new_list


trip_markers = markers_from_trips(cleaned_trips)
print(trip_markers)  
print(len(trip_markers))

marker.location的输出应该是这样的

# [[40.64499, -73.78115],
#  [40.766931, -73.982098],
#  [40.77773, -73.951902],
#  [40.795678, -73.971049]]

这是演示https://repl.it/repls/GroundedVariableSort

Answer 1

列表理解在这里很完美：

>>> [[trip["pickup_latitude"], trip["pickup_longitude"]] for trip in cleaned_trips]
[[40.64499, -73.78115], [40.766931, -73.982098], [40.77773, -73.951902], [40.795678, -73.971049]]

您看到的同一位置附加了12次，因为您只创建了一次marker（在读取marker = {}的行中），然后在一个循环中多次附加。要每次都在列表中附加一个新字典，请确保在每个循环上创建一个新字典：

def markers_from_trips(trips):
    new_list = []
    for trip in trips:
        marker = {"location": [trip["pickup_latitude"], trip["pickup_longitude"]]}
        new_list.append(marker)
    return new_list

或者，再次使用列表理解：

>>> [{"location": [trip["pickup_latitude"], trip["pickup_longitude"]]} for trip in cleaned_trips]
[{'location': [40.64499, -73.78115]}, {'location': [40.766931, -73.982098]}, {'location': [40.77773, -73.951902]}, {'location': [40.795678, -73.971049]}]

带有位置列表的标记对象

1 个答案: