读取和格式化多级，不均匀的 JSON

编程问答 2022-05-29

问题描述

我有一个如下所示的 JSON

{
  "timestamps": [
    "2020-12-17T20:05:00Z","2020-12-17T20:10:00Z","2020-12-17T20:15:00Z","2020-12-17T20:20:00Z","2020-12-17T20:25:00Z","2020-12-17T20:30:00Z"
  ],"properties": [
    {
      "values": [
        -20.58975828559592,-19.356728999226693,-19.808982964173023,-19.673928070777993,-19.712275037138411,-19.48422739982918
      ],"name": "Neg Flow","type": "Double"
    },{
      "values": [
        2,20,19,16
      ],"name": "Event Count","type": "Long"
    }
  ],"progress": 100.0
}

如何将其转换为如下所示的数据框。虽然我能够遍历单个数据项，但我很想知道是否有一种巧妙的方法来做到这一点？

+----------------------+---------------------+-------------+
|Time Stamps           | Neg Flow            | Event Count |
+----------------------+---------------------+-------------+
|2020-12-17T20:05:00Z  |-20.58975828559592   | 2           |
+----------------------+---------------------+-------------+
|2020-12-17T20:10:00Z  |-19.356728999226693  | 20          |
+----------------------+---------------------+-------------+

解决方法

这是一种方法。

library(jsonlite) # read json
library(dplyr) # maniputate data frame
library(magrittr) # for the use of %<>%

# temp.json is my file using the content you provided
json_data <- read_json("temp.json")

# initial data with timestamp
data <- tibble(`Time Stamps` = unlist(json_data[["timestamps"]]))

# properties process
for (property in json_data[["properties"]]) {
  property_name <- property[["name"]]
  # using dynamic namming for more reference please refer to link at end of post
  data %<>% mutate({{property_name}} := unlist(property[["values"]]))
}

输出：

# A tibble: 6 x 3
  `Time Stamps`        `Neg Flow` `Event Count`
  <chr>                     <dbl>         <int>
1 2020-12-17T20:05:00Z      -20.6             2
2 2020-12-17T20:10:00Z      -19.4            20
3 2020-12-17T20:15:00Z      -19.8            19
4 2020-12-17T20:20:00Z      -19.7            20
5 2020-12-17T20:25:00Z      -19.7            19
6 2020-12-17T20:30:00Z      -19.5            16

在此处了解有关使用 dplyr 进行编程的更多信息：

https://cran.r-project.org/web/packages/dplyr/vignettes/programming.html

jsonliterrtidyverse