json - 如何使用 R 解析 DataFrame 列中的 JSON

Question

我怎么从这里来...

| ID | JSON Request                                                          |
==============================================================================
|  1 | {"user":"xyz1","weightmap": {"P1":0,"P2":100}, "domains":["a1","b1"]} |
------------------------------------------------------------------------------
|  2 | {"user":"xyz2","weightmap": {"P1":100,"P2":0}, "domains":["a2","b2"]} |
------------------------------------------------------------------------------

到这里(要求是在第 2 列中制作一个 JSON 表):

| User | P1 | P2 | domains | 
============================
| xyz1 |  0 |100 | a1, b1  |
----------------------------
| xyz2 |100 | 0  | a2, b2  |
----------------------------

这是生成 data.frame 的代码:

raw_df <- 
  data.frame(
    id   = 1:2,
    json = 
      c(
        '{"user": "xyz2", "weightmap": {"P1":100,"P2":0}, "domains": ["a2","b2"]}', 
        '{"user": "xyz1", "weightmap": {"P1":0,"P2":100}, "domains": ["a1","b1"]}'
      ), 
    stringsAsFactors = FALSE
  )

Answer 1

如果您愿意以长格式工作(在本例中为 domains)，这里有一个 tidyverse 解决方案(也使用 jsonlite):

library(jsonlite)
library(dplyr)
library(purrr)
library(tidyr)

d <- data.frame(
  id = c(1, 2),
  json = c(
    '{"user":"xyz1","weightmap": {"P1":0,"P2":100}, "domains":["a1","b1"]}',
    '{"user":"xyz2","weightmap": {"P1":100,"P2":0}, "domains":["a2","b2"]}'
  ),
  stringsAsFactors = FALSE
)

d %>% 
  mutate(json = map(json, ~ fromJSON(.) %>% as.data.frame())) %>% 
  unnest(json)
#>   id user weightmap.P1 weightmap.P2 domains
#> 1  1 xyz1            0          100      a1
#> 2  1 xyz1            0          100      b1
#> 3  2 xyz2          100            0      a2
#> 4  2 xyz2          100            0      b2

mutate...正在从字符串转换为嵌套数据框列。

unnest...正在将这些数据框拆分为多列