Python 若在value中找到嵌套dict中另一个键的值，则替换dict中的值

我有以下嵌套的dict：

 ex_dict = {'path1':
             {'$variable1': '2018-01-01',
              '$variable2': '2020-01-01',
              '$variable3': '$variable1',
              '$variable4': '$variable3'},
            'path2':
             {'$variable1': '2018-01-01',
              '$variable2': '2020-01-01',
              '$variable3': '$variable1',
              '$variable4': '$variable1 + $variable2'}
           }

如果在原始dict键的值中找到另一个dict值的键如果，我想用另一个键的dict值替换为dict键指定的任何$variableX。请参见下面的示例输出：

{'path1':
         {'$variable1': '2018-01-01',
          '$variable2': '2020-01-01',
          '$variable3': '2018-01-01',  # Substituted with value from key:variable1
          '$variable4': '2018-01-01'}, # Substituted with value from key:variable3 (after variable3 was substituted with variable1)    
 'path2':
         {'$variable1': '2018-01-01',
          '$variable2': '2020-01-01',
          '$variable3': '2018-01-01',  # Substituted with value from key:variable1
          '$variable4': '2018-01-01 + 2020-01-01'} # Substituted with value from key:variable3 (after variable3 was substituted with variable1) and key:variable2
       }  

---

有人有什么建议吗

您可以通过递归遍历dict并使用

re

库来进行替换

import re

def process_dict(d):
    reprocess = []
    keys = d.keys()
    while keys:
        for k in keys:
            v = d[k]
            if isinstance(v, dict):
                process_dict(v)
            elif '$' in v:
                d[k] = re.sub(r'\$\w+', lambda m: d[m.group(0)] if m.group(0) in d else m.group(0), v)
                if '$' in d[k] and d[k] != v:
                    reprocess.append(k)
        keys = reprocess
        reprocess = []

编辑：

我添加了一个重新处理步骤来处理引用被链接的情况，并且需要多次通过字典中的一些键来完全处理它们。

这不是一个非常Pythonic的解决方案，但是，它的技巧是：

ex_dict = {'path1':
               {'$variable1': '2018-01-01',
                '$variable2': '2020-01-01',
                '$variable3': '$variable1',
                '$variable4': '$variable3'},
           'path2':
               {'$variable1': '2018-01-01',
                '$variable2': '2020-01-01',
                '$variable3': '$variable1',
                '$variable4': '$variable1 + $variable2'}
           }

for path, d in ex_dict.items():
    for k, v in d.items():
        if v.startswith('$variable'):
            try:
                if '+' in v:
                    ex_dict[path][k] = ' + '.join(ex_dict[path][x.strip()] for x in v.split('+'))
                else:
                    ex_dict[path][k] = ex_dict[path][v]
            except KeyError:
                pass

pprint(ex_dict)

输出：

{'path1': {'$variable1': '2018-01-01',
           '$variable2': '2020-01-01',
           '$variable3': '2018-01-01',
           '$variable4': '2018-01-01'},
 'path2': {'$variable1': '2018-01-01',
           '$variable2': '2020-01-01',
           '$variable3': '2018-01-01',
           '$variable4': '2018-01-01 + 2020-01-01'}}

{'path2': {'$variable4': '2018-01-01 + 2020-01-01', '$variable2': '2020-01-01', '$variable3': '2018-01-01', '$variable1': '2018-01-01'}, 'path1': {'$variable4': '$variable1', '$variable2': '2020-01-01', '$variable3': '2018-01-01', '$variable1': '2018-01-01'}}

---

您可以使用字典理解：

import re
dict = {'path1':
     {'$variable1': '2018-01-01',
      '$variable2': '2020-01-01',
      '$variable3': '$variable1',
      '$variable4': '$variable3'},
    'path2':
     {'$variable1': '2018-01-01',
      '$variable2': '2020-01-01',
      '$variable3': '$variable1',
      '$variable4': '$variable1 + $variable2'}
   }

final_data = {a:{c:d if re.findall('\d+-\d+-\d+', d) else \
re.sub('\$\w+', '{}', d).format(*[b[i] for i in re.findall('\$\w+', d)]) \
 for c, d in b.items()} for a, b in dict.items()}

输出：

{'path1': {'$variable1': '2018-01-01',
           '$variable2': '2020-01-01',
           '$variable3': '2018-01-01',
           '$variable4': '2018-01-01'},
 'path2': {'$variable1': '2018-01-01',
           '$variable2': '2020-01-01',
           '$variable3': '2018-01-01',
           '$variable4': '2018-01-01 + 2020-01-01'}}

{'path2': {'$variable4': '2018-01-01 + 2020-01-01', '$variable2': '2020-01-01', '$variable3': '2018-01-01', '$variable1': '2018-01-01'}, 'path1': {'$variable4': '$variable1', '$variable2': '2020-01-01', '$variable3': '2018-01-01', '$variable1': '2018-01-01'}}

---

你不应该给字典命名，因为这是一个内置的名字。