更改列表中每个字典的特定键的值 - python

Question

我有一个字典列表，如下所示。

[{"type": "df_first",
      "from": "2020-02-01T20:00:00.000Z",
      "to": "2020-02-03T20:00:00.000Z",
      "days":0,
      "coef":[0.1,0.1,0.1,0.1,0.1,0.1]
      },
 {"type": "quadratic",
  "from": "2020-02-03T20:00:00.000Z",
  "to": "2020-02-10T20:00:00.000Z",
  "days":3,
  "coef":[0.1,0.1,0.1,0.1,0.1,0.1]
      },
{"type": "linear",
      "from": "2020-02-04T20:00:00.000Z",
      "to": "2020-02-03T20:00:00.000Z",
      "days":3,
      "coef":[0.1,0.1,0.1,0.1,0.1,0.1]
      },
{"type": "polynomial",
 "from": "2020-02-08T20:00:00.000Z",
 "to": "2020-02-08T20:00:00.000Z",
 "days":3,
 "coef":[0.1,0.1,0.1,0.1,0.1,0.1]
      }
]

从上面的字典中，我想将每个字典的“to”值替换为下一个字典的“from”值。

最后一个字典的“to”值保持原样

预期输出：

[{"type": "df_first",
          "from": "2020-02-01T20:00:00.000Z",
          "to": "2020-02-03T20:00:00.000Z",
          "days":0,
          "coef":[0.1,0.1,0.1,0.1,0.1,0.1]
          },
     {"type": "quadratic",
      "from": "2020-02-03T20:00:00.000Z",
      "to": "2020-02-04T20:00:00.000Z",
      "days":3,
      "coef":[0.1,0.1,0.1,0.1,0.1,0.1]
          },
    {"type": "linear",
          "from": "2020-02-04T20:00:00.000Z",
          "to": "2020-02-08T20:00:00.000Z",
          "days":3,
          "coef":[0.1,0.1,0.1,0.1,0.1,0.1]
          },
    {"type": "polynomial",
     "from": "2020-02-08T20:00:00.000Z",
     "to": "2020-02-08T20:00:00.000Z",
     "days":3,
     "coef":[0.1,0.1,0.1,0.1,0.1,0.1]
          }]

Answer 1

从records（字典列表）创建一个新数据框，然后在from 列上使用Series.shift + Series.fillna 和tocolumn 并将其分配回to 列，接下来使用@987654323 @ 获取字典列表：

df = pd.DataFrame(records)
df['to'] = df['from'].shift(-1).fillna(df['to'])
records = df.to_dict('r')

结果：

# print(records)

[{'type': 'df_first',
  'from': '2020-02-01T20:00:00.000Z',
  'to': '2020-02-03T20:00:00.000Z',
  'days': 0,
  'coef': [0.1, 0.1, 0.1, 0.1, 0.1, 0.1]},
 {'type': 'quadratic',
  'from': '2020-02-03T20:00:00.000Z',
  'to': '2020-02-04T20:00:00.000Z',
  'days': 3,
  'coef': [0.1, 0.1, 0.1, 0.1, 0.1, 0.1]},
 {'type': 'linear',
  'from': '2020-02-04T20:00:00.000Z',
  'to': '2020-02-08T20:00:00.000Z',
  'days': 3,
  'coef': [0.1, 0.1, 0.1, 0.1, 0.1, 0.1]},
 {'type': 'polynomial',
  'from': '2020-02-08T20:00:00.000Z',
  'to': '2020-02-08T20:00:00.000Z',
  'days': 3,
  'coef': [0.1, 0.1, 0.1, 0.1, 0.1, 0.1]}]