[英]Recursively iterate over lists
我正在解析JSON,并尝试基于“父母”键递归地创建树,但仍在努力获取我期望的输出。 这是JSON:
{
"cases": [
{
"name": "A",
"parents": [
"E",
"B"
]
},
{
"name": "B",
"parents": [
"C",
"D"
]
},
{
"name": "C",
"parents": [
"E"
]
},
{
"name": "D",
"parents": [
"E"
]
},
{
"name": "E",
"parents": [
]
}
]
}
这是我的代码:
import json
import copy
FILE="somefile.json"
def find_path(test_name, data, current_steps):
tc = return_test_data(test_name, data)
parents = tc.get('parents', [])
if not current_steps:
current_steps.append(test_name)
if not parents:
return current_steps
else:
temp_steps = []
for step in parents:
new_c_s = copy.deepcopy(current_steps)
new_c_s.append(step)
new_steps = find_path(step, data, new_c_s)
temp_steps.append(new_steps)
return temp_steps
def return_test_data(test_name, data):
for test in data['cases']:
if test['name'] == test_name:
return test
return False
if __name__ == "__main__":
data = json.load(open(FILE))
steps = find_path("A", data, [])
print ("Steps: {}".format(steps))
我希望能看到按照其找到顺序排列的父母名单:
Steps: ['A', 'E', 'B', 'C', 'E', 'D', 'E']
在这种情况下,A有两个父母:E&B。对两个父母进行迭代,得到的结果是:
['A', 'E', {parents of E}, 'B', {parents of B}].
由于E没有父母,而B有C和D的父母,因此(在我看来)变为:
['A', 'E', 'B', 'C', {parents of C}', 'D', {parents of D}]
最终变为:
['A', 'E', 'B', 'C', 'E', 'D', 'E']
相反,我得到:
Steps: [['A', 'E'], [[['A', 'B', 'C', 'E']], [['A', 'B', 'D', 'E']]]]
我确定我递归过多,但无法确切知道是什么。
您可以像这样迭代结构:
parents_list = []
for record in data:
if record['name'] not in parents_list:
parents_list.append(record['name'])
for p in record['parents']:
parents_list.append(p)
print(parents_list)
['A', 'E', 'B', 'C', 'E', 'D', 'E']
看来您使每个步骤都变得比必要的要复杂一些。 我相信这会产生您想要的信息:
import json
FILE = "somefile.json"
def find_path(test_name, data):
dictionary = return_test_data(test_name, data)
if dictionary:
current_steps = [test_name]
if 'parents' in dictionary:
for parent in dictionary['parents']:
current_steps.extend(find_path(parent, data))
return current_steps
return None
def return_test_data(name, data):
for dictionary in data['cases']:
if dictionary['name'] == name:
return dictionary
return None
if __name__ == "__main__":
data = json.load(open(FILE))
steps = find_path("A", data)
print("Steps:", steps)
OUTPUT
> python3 test.py
Steps: ['A', 'E', 'B', 'C', 'E', 'D', 'E']
>
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