[英]How can I check if a value exists in a dictionary that is nested within a loop
[英]How to know if a value exists in a list within a nested dictionary
我如何檢查字典中是否存在“安娜”? 挑戰似乎正在訪問列表中的值:
data = {"Pam": {"Job":"Pilot",
"YOB": "1986",
"Children": ["Greg", "Anna","Sima"]},
"Joe": {"Job":"Engineer",
"YOB": "1987"}}
如果您的詞典如上所述,並且您只想測試“ Anna”是否在“ Pam”子詞典的“ Children”列表中,則只需執行以下操作:
print("Anna" in data["Pam"]["Children"])
但我認為您實際上想要更一般的東西。 ;)
這是一個遞歸函數,它將檢查由嵌套字典和列表組成的對象,尋找給定值。 外部對象可以是字典或列表,因此適合處理從JSON創建的對象。 請注意,它會忽略dict鍵,而只會查看值。 它會根據需要進行深度遞歸以找到匹配值,但是一旦找到匹配項,它將立即停止搜索。
def has_value(obj, val):
if isinstance(obj, dict):
values = obj.values()
elif isinstance(obj, list):
values = obj
if val in values:
return True
for v in values:
if isinstance(v, (dict, list)) and has_value(v, val):
return True
return False
# Test
data = {
"Pam": {
"Job": "Pilot",
"YOB": "1986",
"Children": ["Greg", "Anna", "Sima"]
},
"Joe": {
"Job": "Engineer",
"YOB": "1987"
}
}
vals = ("Pam", "Pilot", "1986", "1987", "1988", "YOB", "Greg",
"Anna", "Sima", "Engineer", "Doctor")
for v in vals:
print(v, has_value(data, v))
輸出
Pam False
Pilot True
1986 True
1987 True
1988 False
YOB False
Greg True
Anna True
Sima True
Engineer True
Doctor False
您傳遞給has_value
的obj
必須是字典或列表,否則將失敗
UnboundLocalError: local variable 'values' referenced before assignment
您可以將any
與列表推導一起使用,以檢查'Anna'
是否作為字典中的鍵存在或作為子詞典中的元素出現:
data = {"Pam": {"Job":"Pilot",
"YOB": "1986",
"Children": ["Greg", "Anna","Sima"]},
"Joe": {"Job":"Engineer",
"YOB": "1987"}}
if any(a == 'Anna' or 'Anna' in b.get('children', []) for a, b in data.items()):
pass
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