从python中复杂的数据结构中提取数据

Question

我有一个像

这样的数据结构

[ {'uid': 'test_subject145', 'class':'?',  'data':[  {'chunk':1, 'writing':[ ['this is exciting'],[ 'you are good' ]... ]}  ]  },
  {'uid': 'test_subject166', 'class':'?',  'data':[  {'chunk':2, 'writing':[ ['he died'],[ 'go ahead' ]... ]}  ] }, ...]

它是一个包含许多字典的列表，每个字典有 3 对 'uid': 'test_subject145', 'class':'?', 'data':[]。 在最后一对 'data' 中，该值是一个列表，它再次包含一个字典，其中包含 2 对 'chunk':1, 'writing':[]，在 'writing '，它的值是一个列表，又包含许多列表。 我要提取的是所有这些句子的内容，如'this is exciting' 和'you are good' 等，然后放入一个简单的列表中。其最终形式应为 list_final = ['this is exciting', 'you are good', 'he died',... ]

Answer 1

鉴于您的原始列表名为 input，只需使用列表理解：

[elem for dic in input
      for dat in dic.get('data',())
      for writing in dat.get('writing',())
      for elem in writing]

您可以使用.get(..,())，这样如果没有这样的键，它仍然有效：如果没有这样的键，我们返回空元组()，因此没有迭代。

根据您的示例输入，我们得到：

>>> input = [ {'uid': 'test_subject145', 'class':'?',  'data':[  {'chunk':1, 'writing':[ ['this is exciting'],[ 'you are good' ]]}  ]  },
...       {'uid': 'test_subject166', 'class':'?',  'data':[  {'chunk':2, 'writing':[ ['he died'],[ 'go ahead' ] ]}  ] }]
>>> 
>>> [elem for dic in input
...       for dat in dic.get('data',())
...       for writing in dat.get('writing',())
...       for elem in writing]
['this is exciting', 'you are good', 'he died', 'go ahead']

Answer 2

tl;博士

[str for dic in data
     for data_dict in dic['data']
     for writing_sub_list in data_dict['writing']
     for str in writing_sub_list]

慢慢来，一次做一层。然后重构您的代码以使其更小。

data = [{'class': '?',
         'data': [{'chunk': 1,
                   'writing': [['this is exciting'], ['you are good']]}],
         'uid': 'test_subject145'},
        {'class': '?',
         'data': [{'chunk': 2,
         'writing': [['he died'], ['go ahead']]}],
         'uid': 'test_subject166'}]

for d in data:
    print(d)
# {'class': '?', 'uid': 'test_subject145', 'data': [{'writing': [['this is exciting'], ['you are good']], 'chunk': 1}]}
# {'class': '?', 'uid': 'test_subject166', 'data': [{'writing': [['he died'], ['go ahead']], 'chunk': 2}]}

for d in data:
     data_list = d['data']
     print(data_list)
# [{'writing': [['this is exciting'], ['you are good']], 'chunk': 1}]
# [{'writing': [['he died'], ['go ahead']], 'chunk': 2}]

for d in data:
     data_list = d['data']
     for d2 in data_list:
         print(d2)
# {'writing': [['this is exciting'], ['you are good']], 'chunk': 1}
# {'writing': [['he died'], ['go ahead']], 'chunk': 2}

for d in data:
     data_list = d['data']
     for d2 in data_list:
         writing_list = d2['writing']
         print(writing_list)
# [['this is exciting'], ['you are good']]
# [['he died'], ['go ahead']]

for d in data:
     data_list = d['data']
     for d2 in data_list:
         writing_list = d2['writing']
         for writing_sub_list in writing_list:
             print(writing_sub_list)
# ['this is exciting']
# ['you are good']
# ['he died']
# ['go ahead']

for d in data:
     data_list = d['data']
     for d2 in data_list:
         writing_list = d2['writing']
         for writing_sub_list in writing_list:
             for str in writing_sub_list:
                  print(str)
# this is exciting
# you are good
# he died
# go ahead

然后要转换成更小（但难以阅读）的东西，像这样重写上面的代码。应该很容易看出如何从一个到另一个：

strings = [str for d in data for d2 in d['data'] for wsl in d2['writing'] for str in wsl]
# ['this is exciting', 'you are good', 'he died', 'go ahead']

然后，用像威廉的回答这样更好的名字让它更漂亮：

[str for dic in data
     for data_dict in dic['data']
     for writing_sub_list in data_dict['writing']
     for str in writing_sub_list]

Answer 3

所以我相信下面会起作用

lista = [ {'uid': 'test_subject145', 'class':'?',  'data':[  {'chunk':1, 'writing':[ ['this is exciting'],[ 'you are good' ]... ]}  ]  },
          {'uid': 'test_subject166', 'class':'?',  'data':[  {'chunk':2, 'writing':[ ['he died'],[ 'go ahead' ]... ]}  ] }, ...]

list_of_final_products = []

for itema in lista:
  try:
    for data_item in itema['data']:
      for writa in data_item['writing']:
        for writa_itema in writa:
          list_of_final_products.append(writa)
  except:
    pass

上面提到的这个项目，我相信对理解有帮助 - python getting a list of value from list of dict（感谢 McGrady）