英文:
How can I iterate through a list of dictionaries and extract a subset of values in Python using loops?
问题
我有一个Python列表，如下所示：
data_list等于字典对象中的“values”键，该字典对象是一个项目列表
"values": [
{
"a": 1,
"b": 2,
"center code here": 3,
"d": 4
},
{
"a": 1,
"b": 2,
"c": 3,
"d": 4
},
{
"a": 1,
"b": 2,
"c": 3,
"d": 4
},
{
"a": 1,
"b": 2,
"c": 3,
"d": 4
}
]
我还有另一个列表，其中包含我想要的值：
listx = ["a", "b"]
这是我尝试过的代码：
listx = ["a", "b"]
dict2 = {}
for d in data_list:
for v, x in d.items():
if v in listx:
dict2[v] = x
print(len(dict2))
我得到的结果是12，这是一个字典中的项目数。它没有遍历其他字典。有人可以帮忙吗？
我的目标是能够创建一个具有以下值的列表子集：
"values": [
{
"a": 1,
"b": 2
},
{
"a": 1,
"b": 2
},
{
"a": 1,
"b": 2
},
{
"a": 1,
"b": 2
}
]
有人可以帮助我吗？我做错了什么？
英文:
Iterate through a list of dictionaries to get subset
I have a python list as follows:
data_list is equivalent to values key
in a dictionary object which is a list of items
"values": [
{
"a": 1,
"b": 2,
"center code here": 3,
"d": 4,
},
{
"a": 1,
"b": 2,
"c": 3
"d": 4,
},
{
"a": 1,
"b": 2,
"c": 3
"d": 4,
},
{
"a": 1,
"b": 2,
"c": 3
"d": 4,
}
]
I also have another list that holds the values i want
listx = [a,b]
This is what i tried :
listx = [a,b]
dict2 = {}
for d in data_list:
for v,x in d.items():
if v in listx:
dict2[v] = (x)
print(len(dict2))
I get 12 which is the number of items in one dictionary. It doesn't iterate over the other dictionaries?
Can anyone help ?
My goal is to be able to create a subset of this list with the following values :
"values": [
{
"a": 1,
"b": 2
},
{
"a": 1,
"b": 2
},
{
"a": 1,
"b": 2
},
{
"a": 1,
"b": 2
}
]
Can anyone help me here ? What am i doping wrong?
答案1
得分: 3
以下是您要翻译的代码部分：
values = [
{
"a": 1,
"b": 2,
"c": 3,
"d": 4,
},
{
"a": 1,
"b": 2,
"c": 3,
"d": 4,
},
{
"a": 1,
"b": 2,
"c": 3,
"d": 4,
},
{
"a": 1,
"b": 2,
"c": 3,
"d": 4,
},
]
listx = ["a", "b"]
values_filtered = [{k: v for k, v in d.items() if k in listx} for d in values]
print(values_filtered)
输出：
[
{"a": 1, "b": 2},
{"a": 1, "b": 2},
{"a": 1, "b": 2},
{"a": 1, "b": 2}
]
英文:
You can use simple list comprehension to filter the values:
values = [
{
"a": 1,
"b": 2,
"c": 3,
"d": 4,
},
{
"a": 1,
"b": 2,
"c": 3,
"d": 4,
},
{
"a": 1,
"b": 2,
"c": 3,
"d": 4,
},
{
"a": 1,
"b": 2,
"c": 3,
"d": 4,
},
]
listx = ["a", "b"]
values_filtered = [{k: v for k, v in d.items() if k in listx} for d in values]
print(values_filtered)
Prints:
[
{"a": 1, "b": 2},
{"a": 1, "b": 2},
{"a": 1, "b": 2},
{"a": 1, "b": 2}
]
答案2
得分: 2
以下是您提供的Python代码的翻译部分：
listx = ["a", "b"]
subset = []
for d in data_list:
subset_dict = {}
for key, value in d.items():
if key in listx:
subset_dict[key] = value
subset.append(subset_dict)
print(subset)
输出:
[{'a': 1, 'b': 2}, {'a': 1, 'b': 2}, {'a': 1, 'b': 2}, {'a': 1, 'b': 2}]
或者您可以使用itemgetter：
from operator import itemgetter
listx = ["a", "b"]
subset = [dict(zip(listx, itemgetter(*listx)(d))) for d in data_list]
print(subset)
英文:
listx = ["a", "b"]
subset = []
for d in data_list:
subset_dict = {}
for key, value in d.items():
if key in listx:
subset_dict[key] = value
subset.append(subset_dict)
print(subset)
Output:
[{'a': 1, 'b': 2}, {'a': 1, 'b': 2}, {'a': 1, 'b': 2}, {'a': 1, 'b': 2}]
Or you can use itemgetter:
from operator import itemgetter
listx = ["a", "b"]
subset = [dict(zip(listx, itemgetter(*listx)(d))) for d in data_list]
print(subset)
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