如何将列表元素添加到字典中

Question

假设我有 dict = {'a': 1, 'b': 2'} 并且我还有一个列表 = ['a', 'b, 'c', 'd', 'e'] .目标是将列表元素添加到字典中，并打印出新的 dict 值以及这些值的总和。应该是这样的：

2 a
3 b
1 c
1 d
1 e
Total number of items: 8

相反，我得到：

1 a
2 b
1 c
1 d
1 e
Total number of items: 6

到目前为止我所拥有的：

def addToInventory(inventory, addedItems)
    for items in list():
        dict.setdefault(item, [])

def displayInventory(inventory):
    print('Inventory:')
    item_count = 0
    for k, v in inventory.items():
       print(str(v) + ' ' + k)
       item_count += int(v)
    print('Total number of items: ' + str(item_count))

newInventory=addToInventory(dict, list)
displayInventory(dict)

任何帮助将不胜感激！

Answer 1

如果键已经存在，您只需迭代列表并根据键增加计数，否则将其设置为 1。

>>> d = {'a': 1, 'b': 2}
>>> l = ['a', 'b', 'c', 'd', 'e']
>>> for item in l:
...     if item in d:
...         d[item] += 1
...     else:
...         d[item] = 1
>>> d
{'a': 2, 'c': 1, 'b': 3, 'e': 1, 'd': 1}

---

你可以用dict.get写同样的，简洁的，像这样

>>> d = {'a': 1, 'b': 2}
>>> l = ['a', 'b', 'c', 'd', 'e']
>>> for item in l:
...     d[item] = d.get(item, 0) + 1
>>> d
{'a': 2, 'c': 1, 'b': 3, 'e': 1, 'd': 1}

dict.get函数会寻找key，如果找到则返回值，否则返回第二个参数传入的值。如果item 已经是字典的一部分，那么将返回对应它的数字，我们将1 添加到它并将其存储回相同的item。如果没有找到，我们将得到 0（第二个参数），然后我们将其加 1 并存储在 item 中。

---

现在，要获得总数，您可以使用sum 函数将字典中的所有值相加，就像这样

>>> sum(d.values())
8

dict.values 函数将返回字典中所有值的视图。在我们的例子中，它将编号，我们只需使用 sum 函数将它们全部添加。

Answer 2

另一种方式：

使用集合模块：

>>> import collections
>>> a = {"a": 10}
>>> b = ["a", "b", "a", "1"]
>>> c = collections.Counter(b) + collections.Counter(a)
>>> c
Counter({'a': 12, '1': 1, 'b': 1})
>>> sum(c.values())
14

Answer 3

如果您正在使用 Python 自动化无聊的东西中的 List to Dictionary Function for Fantasy Game Inventory 寻找解决方案，下面是一个有效的代码：

# inventory.py
stuff = {'rope': 1, 'torch': 6, 'gold coin': 42, 'dagger': 1, 'arrow': 12}

#this part of the code displays your current inventory
def displayInventory(inventory): 
    print('Inventory:')
    item_total = 0

    for k, v in inventory.items():
        print(str(v) + ' ' + k)
        item_total += v
    print("Total number of items: " + str(item_total))

#this launches the function that displays your inventory
displayInventory(stuff) 

dragonLoot = ['gold coin', 'dagger', 'gold coin', 'gold coin', 'ruby']

# this part is the function that adds the loot to the inventory
def addToInventory (inventory, addedItems): 

    print('Your inventory now has:')

#Does the dict has the item? If yes, add plus one, the default being 0
    for item in addedItems:
        stuff[item] = stuff.get(item, 0) + 1 


# calls the function to add the loot
addToInventory(stuff, dragonLoot) 
# calls the function that shows your new inventory
displayInventory(stuff) 

Answer 4

关于“幻想游戏清单的字典函数列表”的问题 - 第 5 章。使用 Python 自动化无聊的东西。

# This is an illustration of the dictionaries

# This statement is just an example inventory in the form of a dictionary
inv = {'gold coin': 42, 'rope': 1}
# This statement is an example of a loot in the form of a list
dragon_loot = ['gold coin', 'dagger', 'gold coin', 'gold coin', 'ruby']

# This function will add each item of the list into the dictionary
def add_to_inventory(inventory, dragon_loot):

    for loot in dragon_loot:
        inventory.setdefault(loot, 0) # If the item in the list is not in the dictionary, then add it as a key to the dictionary - with a value of 0
        inventory[loot] = inventory[loot] + 1 # Increment the value of the key by 1

    return inventory

# This function will display the dictionary in the prescribed format
def display_inventory(inventory):

    print('Inventory:')
    total_items = 0

    for k, v in inventory.items():
        print(str(v) + ' ' + k)
        total_items = total_items + 1

    print('Total number of items: ' + str(total_items))

# This function call is to add the items in the loot to the inventory
inv = add_to_inventory(inv, dragon_loot)

# This function call will display the modified dictionary in the prescribed format
display_inventory(inv)

Answer 5

使用collections.Counter，因为它拥有您手头任务所需的一切：

from collections import Counter

the_list = ['a', 'b', 'c', 'd', 'e']

counter = Counter({'a': 1, 'b': 2})
counter.update(the_list)

for c in sorted(counter):
    print c, counter[c]

为了获得总数，您可以简单地将 counter 的值相加：

sum(counter.values())
# 8

Answer 6

stuff={'rope':1,'torch':6,'gold coin':42,'dagger':1,'arrow':12}
dragonLoot = ['gold coin', 'dagger', 'gold coin', 'gold coin', 'ruby']

def displayInventory(inventory):
    print('Inventory:')
    item_total=0
    for k,v in inventory.items():
        print(str(v)+' '+k)
        item_total=item_total+v
    print('Total number of items: '+ str(item_total))

def addToInventory(inventory,addedItems):
    for v in addedItems:
        if v in inventory.keys():
            inventory[v]+=1
        else:
            inventory[v]=1

addToInventory(stuff,dragonLoot)    

displayInventory(stuff)

Answer 7

invent = {'rope': 1, 'torch':6, 'gold coin': 42, 'dagger':1, 'arrow':12}
dragonLoot = ['gold coin', 'dagger', 'gold coin', 'gold coin', 'ruby']

def displayInventory(weapons):
    print('Inventory')
    total = 0
    for k, v in weapons.items():
        print(str(v), k)
        total += v
    print('Total number of items: ' + str(total))

def addToInventory(inventory, addedItems):
    for item in addedItems:
        inventory.setdefault(item, 0)
        inventory[item] = inventory[item] + 1
    return(inventory)



displayInventory(addToInventory(invent, dragonLoot))

Answer 8

对于您问题的第一部分，要将列表项添加到字典中，我使用了以下代码：

inventory = {'gold coin': 42, 'rope': 1}
dragonLoot = ['gold coin', 'dagger', 'gold coin', 'gold coin', 'ruby']

def addToInventory(inventory, addedItems):
    for i in addedItems:
        if i in inventory:
            inventory[i] = inventory[i] + 1
        else:
            inventory[i] = 1 #if the item i is not in inventory, this adds it
                             #   and gives the value 1.

我之所以分享它，是因为我在 .get 函数中使用了 if 语句，就像其他 cmets 一样。现在我学习了.get，它似乎比我的代码更简单、更短。但是在我遇到这个练习的“自动化无聊的东西”一书的章节中，我还没有学习（或者说不够好）.get 函数。

至于显示库存的功能，我和其他cmets的代码是一样的：

def displayInventory(inventory):
    print('Inventory:')
    tItems = 0 
    for k, v in inventory.items(): 
        print(str(v) + ' ' + k)
    for v in inventory.values():
        tItems += v
    print()
    print('Total of number of items: ' + str(tItems))

我调用了这两个函数，结果如下：

>>> addToInventory(inventory, dragonLoot)
>>> displayInventory(inventory)

Inventory:
45 gold coin
1 rope
1 dagger
1 ruby

Total of number of items: 48

我希望这会有所帮助。

Answer 9

def addToInventory(inventory, addedItems):
    for v in addedItems:
        if v in inventory.keys():
            inventory[v] += 1
        else:
            inventory[v] = 1
    return inventory

inv = {'gold coin': 42, 'rope': 1}
dragonLoot = ['gold coin', 'dagger', 'gold coin', 'gold coin', 'ruby']
inv = addToInventory(inv, dragonLoot)
displayInventory(inv)

Answer 10

对于这个问题的第一部分，这是我想出的代码。

invt = {'rope': 1, 'torch': 6, 'gold coin': 42, 'dagger': 1, 'arrow': 12}
print ("Inventory:")
total = sum(invt.values())
for x, v in invt.items():
  print (str(v) + ' ' + x)
print ("Total number of items: {}".format(total))

我看到大多数人都在通过循环进行交互以添加到总变量中。但是使用 sum 方法，我跳过了一步..

随时接受反馈....

Answer 11

以下是使用上述技巧的代码，加上名词复数的细微变化。对于那些愿意和勇敢的人来说，有 ifs 和 elifs 的任务来处理异常;)

# sets your dictionary
backpack = {'rope': 1, 'torch': 6, 'gold coin': 42, 'dagger': 1, 'arrow': 12}

# this function display your current inventory
def displayInventory(inventory):
    print("Backpack:")
    itemTotal = 0
    for k, v in inventory.items():

    # creates a simple plural version of the noun 
    # (adds only the letter "s" at the end of the word) does not include exceptions 
    # (for example, torch - 'torchs' (should be 'torches'), etc.
        if v > 1:
            print(str(v) + ' ' + k +'s')
        else:
            print(str(v) + ' ' + k)

        itemTotal += v
    print("Total quantity of items: " + str(itemTotal))

# sets your loot 
dragonLoot = ['gold coin', 'dagger', 'gold coin', 'gold coin', 'ruby']

# this function adds your loot to your inventory
def addToInventory(inventory, addedItems):
    for item in addedItems:
        inventory[item] = inventory.get(item,0) + 1

# launch your functions
addToInventory(backpack, dragonLoot)
displayInventory(backpack)