嵌套(二维)字典的类迭代器

Question

我断断续续使用python好几年了，但对于复杂的面向对象编程来说并不多，而且我很少使用字典作为结构体。对于这个应用程序，我试图在地图上建立一个地理定位的路点数据库。

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。出于可用性和可读性的考虑，我正在尝试实现各种容器方法，但是我在添加类功能时遇到了困难。 容器类 的代码片段

# 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next方法来实现下面测试脚本中的循环功能。

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 = ''

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

与其尝试在GeoWayPtData中支持迭代，不如在GeoWayPtData中迭代默认值:

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

当然，你也可以添加这个功能到GeoWayPtData通过添加一个__iter__产生路径点:

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

那么你可以这样做:

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