r - 如何在 R 中解析具有堆叠多个 JSON 的文件？

Question

我在 R 中有以下“堆叠 JSON”对象，example1.json :

{"ID":"12345","Timestamp":"20140101", "Usefulness":"Yes",
  "Code":[{"event1":"A","result":"1"},…]}
{"ID":"1A35B","Timestamp":"20140102", "Usefulness":"No",
  "Code":[{"event1":"B","result":"1"},…]}
{"ID":"AA356","Timestamp":"20140103", "Usefulness":"No",
  "Code":[{"event1":"B","result":"0"},…]}

这些不是逗号分隔的。基本目标是将某些字段(或所有字段)解析为 R data.frame 或 data.table:

    Timestamp    Usefulness
 0   20140101      Yes
 1   20140102      No
 2   20140103      No

通常，我会在 R 中读取 JSON，如下所示:

library(jsonlite)

jsonfile = "example1.json"
foobar = fromJSON(jsonfile)

然而，这会引发解析错误:

Error: lexical error: invalid char in json text.
          [{"event1":"A","result":"1"},…]} {"ID":"1A35B","Timestamp"
                     (right here) ------^

这是与以下类似的问题，但在 R 中: multiple Json objects in one file extract by python

编辑:这种文件格式称为“换行符分隔的 JSON”，NDJSON。

Answer 1

三个点...使您的 JSON 无效，因此您的 lexical error .

您可以使用 jsonlite::stream_in() '流入' JSON 行。

library(jsonlite)

jsonlite::stream_in(file("~/Desktop/examples1.json"))
# opening file input connection.
# Imported 3 records. Simplifying...
# closing file input connection.
#      ID Timestamp Usefulness Code
# 1 12345  20140101        Yes A, 1
# 2 1A35B  20140102         No B, 1
# 3 AA356  20140103         No B, 0

数据

我已经清理了您的示例数据以使其成为有效的 JSON，并将其作为 ~/Desktop/examples1.json 保存到我的桌面。

{"ID":"12345","Timestamp":"20140101", "Usefulness":"Yes","Code":[{"event1":"A","result":"1"}]}
{"ID":"1A35B","Timestamp":"20140102", "Usefulness":"No","Code":[{"event1":"B","result":"1"}]}
{"ID":"AA356","Timestamp":"20140103", "Usefulness":"No","Code":[{"event1":"B","result":"0"}]}