如何使用循环将列表附加到字典中

Question

我试图将几个列表添加到一个字典中，但它看起来像是在打印循环中的最后一个条目。有什么办法可以避免吗？

list_orbited_planet = ["Earth", "Mars", "Pluto", "Uranus"]
low = ["Earth", "Mars", "Mars", "Uranus"]
high = ["Pluto", "Pluto", "Uranus"]
entities = {'low': low, 'high': high}
listPlanets = []

for i in range(len(list_orbited_planet)):
  entities['low'] = low.count(list_orbited_planet[i])
  entities['high'] = high.count(list_orbited_planet[i])
  orbited_planet = {list_orbited_planet[i]: entities}
  print(orbited_planet)
  listPlanets.append(orbited_planet)

print(listPlanets)

我希望我的输出是这样的：

[{'Earth': {'low': 1, 'high': 0}}, {'Mars': {'low': 2, 'high': 0}}, {'Pluto': {'low': 0, 'high': 2}}, {'Uranus': {'low': 1, 'high': 1}}]

然而，它只在每个值中显示天王星值，所以它实际上是低= 1，高=1到处都是。

Answer 1

我想比以前的回答更进一步，并提出几点建议：

1. 为什么可以简单地执行for planet in planets时使用for i in range循环？(更多的readable)
2. You're在这个循环中定义了太多的变量，而没有任何需要，这只会带来混乱。每个变量都应该表示一些逻辑实体。
3. 您需要在每次迭代中定义一个新的字典，否则以前定义的每一次都会被更新。

这可能会给你这样的结果：

list_orbited_planet = ["Earth", "Mars", "Pluto", "Uranus"]
low = ["Earth", "Mars", "Mars", "Uranus"]
high = ["Pluto", "Pluto", "Uranus"]

listPlanets = []

for planet in list_orbited_planet:
    orbited_planet = {
        planet:
        {
            'low': low.count(planet),
            'high': high.count(planet)
        }
    }
    listPlanets.append(orbited_planet)

print(listPlanets)

Answer 2

您可以在循环中使用临时字典，如下所示：

list_orbited_planet = ["Earth", "Mars", "Pluto", "Uranus"]
low = ["Earth", "Mars", "Mars", "Uranus"]
high = ["Pluto", "Pluto", "Uranus"]
entities = {'low': low, 'high': high}
listPlanets = []

for i in range(len(list_orbited_planet)):
    tmp_entities = {}
    tmp_entities['low'] = low.count(list_orbited_planet[i])
    tmp_entities['high'] = high.count(list_orbited_planet[i])
    orbited_planet = {list_orbited_planet[i]: tmp_entities}
    listPlanets.append(orbited_planet)

print(listPlanets)

它提供了以下输出：

[{'Earth': {'low': 1, 'high': 0}}, {'Mars': {'low': 2, 'high': 0}}, {'Pluto': {'low': 0, 'high': 2}}, {'Uranus': {'low': 1, 'high': 1}}]

如果在其他地方不需要entities，也可以删除它。

Answer 3

list_orbited_planet = ["Earth", "Mars", "Pluto", "Uranus"]
low = ["Earth", "Mars", "Mars", "Uranus"]
high = ["Pluto", "Pluto", "Uranus"]
entities = {'low': low, 'high': high}
listPlanets = []

for i in range(len(list_orbited_planet)):
  newEntities = dict()
  newEntities['low'] = low.count(list_orbited_planet[i])
  newEntities['high'] = high.count(list_orbited_planet[i])
  orbited_planet = {list_orbited_planet[i]: newEntities}
  print(orbited_planet)
  listPlanets.append(orbited_planet)

print(listPlanets)

因为每个循环都要引用您的entities，所以它们实际上是在操作存储在同一个地址中的相同变量。因此，只需声明一个新变量，以避免这种行为。

产出：

{'Earth': {'low': 1, 'high': 0}}
{'Mars': {'low': 2, 'high': 0}}
{'Pluto': {'low': 0, 'high': 2}}
{'Uranus': {'low': 1, 'high': 1}}
[{'Earth': {'low': 1, 'high': 0}}, {'Mars': {'low': 2, 'high': 0}}, {'Pluto': {'low': 0, 'high': 2}}, {'Uranus': {'low': 1, 'high': 1}}]