对照Python字典中的键值检查列表中的值

我有两个数据源，一个是列表，另一个是字典列表。 我的数据如下所示：

need_placeholder = ['1200', '1300', '1400']
ad_dict = [{"Name": "A", "ID": "1999"}, {"Name": "B", "ID": "1299"}, 
           {"Name": "C", "ID": "1400"}]

我需要检查

need\u占位符

项是否等于

ad\u dict

中的

ID

值。这是我的剧本：

for item in need_placeholder:
    adpoint_key = item 
    for index, my_dict in enumerate(ad_dict):
        if my_dict["ID"] == adpoint_key:
            continue
        else:    
            print(f'No key exists for {adpoint_key}')

输出为：

我期望的输出是：

---

我如何在不遍历字典或列表的情况下比较这些值

您的

else

在循环中的位置不正确。对于每个输出，该内部循环运行多次。如果首先将

ID

值拉入一个集合，则可以完全避免该循环：

need_placeholder = ['1200', '1300', '1400']
ad_dict = [{"Name": "A", "ID": "1999"}, {"Name": "B", "ID": "1299"}, {"Name": "C", "ID": "1400"}]

ad_values = set(d['ID'] for d in ad_dict)

for v in need_placeholder:
    if v not in ad_values:
        print(f'no key exits for {v}')

印刷品：

no key exits for 1200
no key exits for 1300

如果顺序不重要，您可以将整个过程作为一组操作来完成：

for v in set(need_placeholder) - ad_values:
    print(f'no key exits for {v}')

你可以试试这个

>>> need_placeholder = ['1200', '1300', '1400']
>>> ad_dict = [{"Name": "A", "ID": "1999"}, {"Name": "B", "ID": "1299"}, 
               {"Name": "C", "ID": "1400"}]
>>> keys={d['ID'] for d in ad_dict} # Set of all unique ID values
>>> [key for key in need_placeholder if not key in keys]
# ['1200', '1300']

你可以用

如果你不在乎秩序

set(need_placeholder)-keys
# {'1300', '1200'}

使用

使用

---

一种快速的方法是使用嵌套列表理解

[print('No key for {}'.format(x)) for x in need_placeholder if x not in [y['ID'] for y in ad_dict]]

---

我建议使用一个类，而不是列表中的那么多字典。我必须保持当前的格式。

list(filterfalse(lambda x:x in keys, need_placeholder))
# ['1200', '1300']

set(need_placeholder)-keys
# {'1300', '1200'}

>>> for key in need_placeholder:
...     if all(key != d['ID'] for d in ad_dict):
...         print(f'No key exists for {key}')
...
No key exists for 1200
No key exists for 1300

>>> for key in need_placeholder:
...     for d in ad_dict:
...             if key==d['ID']:
...                     break
...     else:
...             print(f'No key {key}')
...
No key 1200
No key 1300

[print('No key for {}'.format(x)) for x in need_placeholder if x not in [y['ID'] for y in ad_dict]]

allowed_values = {dic["ID"] for dic in ad_dict}

for item in need_placeholder:
    if item not in allowed_values:
        print(f'No key exists for {item}')

for item in need_placeholder:
    adpoint_key = item
    duplicate_exist = False # flag that will be update if key exists
    for index, my_dict in enumerate(ad_dict):
        if my_dict["ID"] == adpoint_key:
            duplicate_exist = True    # flag is updated as key exists
    not duplicate_exist and print(f'No key exists for {adpoint_key}') # for all non duplicate print function is invoked at the end of inner loop