如何将两个字典列表与 python 中的列表合并？

Question

how can I define a function

def join_data(data_1, data_2):
    
    #code
    
    return joined_data

where

data_1 = [{'paths': [[1,2,3]],  'pos': 1}, {'paths': [[1,2,3]], 'pos': 2},]

data_2 = [{'paths': [[6,7,8]],  'pos': 1}, {'paths': [[4,5,6]], 'pos': 2},]

The function should join paths into the same list by detecting if pos (always have 1 value) from the two data are the same, such that the output is

joined_data = [{'paths': [[1,2,3][6,7,8]],  'pos': 1}, {'paths': [[1,2,3][4,5,6]], 'pos': 2},]

I apologize if I am not clear in any way, and thank you for the help.

Answer 1

You can use an intermediate dictionary with the value of the 'pos' key as its key and merge the 'path' lists of the pos's dictionaries as value. Then build your list bay reforming dictionaries from the items of the intermediate dictionary:

data_1 = [{'paths': [[1,2,3]],  'pos': 1}, {'paths': [[1,2,3]], 'pos': 2},]

data_2 = [{'paths': [[6,7,8]],  'pos': 1}, {'paths': [[4,5,6]], 'pos': 2},]

merged = dict()
for d in data_1 + data_2:
    merged.setdefault(d['pos'],[]).extend(d['paths']) 
merged = [ {'paths':v, 'pos':p} for p,v in merged.items() ]

print(merged)
[{'paths': [[1, 2, 3], [6, 7, 8]], 'pos': 1}, 
 {'paths': [[1, 2, 3], [4, 5, 6]], 'pos': 2}]

Answer 2

Use the following function;

def join_data(data_1, data_2):
    joined_data = []
    for i in data_1:
      for j in data_2:
        if (i['pos'] == j['pos']):
          joined_data.append({'paths': [i['paths'], j['paths']], 'pos': j['pos']})
    return joined_data

Output:

[{'paths': [[[1, 2, 3]], [[6, 7, 8]]], 'pos': 1},
 {'paths': [[[1, 2, 3]], [[4, 5, 6]]], 'pos': 2}]

Answer 3

A function which appends from one list into the other could be like this:

def join_data(data_1, data_2):
    joined_data = data_1.copy()
    for dic in data_2:
        pos = dic['pos']
        path_items = dic['paths']
        for d in joined_data:
            if d['pos'] == pos:
                d['paths'].extend(path_items)
    return joined_data