Question

我一直在使用python几年，但对于复杂的面向对象编程并不多，我很少使用字典作为结构。对于这个应用程序，我正在尝试在地图上建立一个地理位置定位点的数据库。

因此，我想创建一个能够访问二维字典结构并执行各种方法的容器类。为了可用性和可读性，我正在尝试实现各种容器方法，但是我很难添加类功能。

我的容器类的片段

# Python standard libraries
from collections import defaultdict
from GeoWayPt import *
#===========================================================================
class GeoWayPtData():
    """ Geodetic waypoint data container """

    # Nested dictionary structure for equipment/waypoints
    def equip_dict(self): return defaultdict(self.waypt_dict)
    def waypt_dict(self): return GeoWayPt

    def __init__(self):
        """ Constructor """
        #
        self.AvailEquipIndex = 0

        # Nested dictionary of equipment with waypoints
        #
        # First key for each equipment.
        # Second key for each waypoint.
        # [EquipNum][WayptNum]
        self.dictWayPts = defaultdict(self.equip_dict)

我不确定如何实现 iter 和下一个方法，以便在下面的测试脚本中实现循环功能。

我的数据类的一部分

class GeoWayPt():
    """ Geodetic waypoint container class """
    def __init__(self):
        """ Constructor """
        # Equipment ID (integer, starting at 0)
        self.ID = 0
        # Equipment class (string description)
        self.EquipClassStr = ''

我的测试脚本

from GeoWayPt import *
from GeoWayPtData import *

# 2-D data structure
data = GeoWayPtData()

waypt = GeoWayPt()
waypt.ID = 0
waypt.EquipClassStr = "foo"
# Add equipment 0
data.AddEquip(waypt)

waypt = GeoWayPt()
waypt.ID = 0
waypt.EquipClassStr = "bar"
# Add waypoint to equipment 0
data.AddWayPt(0, waypt)

waypt = GeoWayPt()
waypt.ID = 1
waypt.EquipClassStr = "can"
# Add equipment 1
data.AddEquip(waypt)

waypt = GeoWayPt()
waypt.ID = 1
waypt.EquipClassStr = "haz"
# Add waypoint to equipment 1
data.AddWayPt(1, waypt)

waypt = GeoWayPt()
waypt.ID = 1
waypt.EquipClassStr = "sum"
# Add another waypoint to equipment 1
data.AddWayPt(1, waypt)

# Functionality I'd like:
for equip in data:
    for waypt in equip:
        print waypt.ID, waypt.EquipClassStr

Answer 1

不是试图支持GeoWayPtData中的迭代，而是迭代GeoWayPtData中的defaultdict可能更容易：

for equip in data.dictWayPts.itervalues():
    for waypt in equip.itervalues():
        print waypt.ID, waypt.EquipClassStr

当然，您还可以通过添加产生航路点的__iter__将此功能添加到GeoWayPtData：

    def __iter__(self):
        for equip in self.dictWayPts.itervalues():
            for waypt in equip.itervalues():
                yield waypt

然后你可以这样做：

for waypt in data:
    print waypt.ID, waypt.EquipClassStr

嵌套（2-D）字典的类迭代器？

1 个答案: