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rjsonlite

Write json scalars in R

In , I have some data in a data frame and need to export it to jsonl. In jsonl each line is its own valid json. As the linked question shows, you can easily do that by applying jsonlite::toJSON() to each row. My problem is that I need one of the variables to be a scalar string, but toJSON makes any vector R vector into a list:

library(tidyverse)
library(jsonlite)
#> 
#> Attaching package: 'jsonlite'
#> The following object is masked from 'package:purrr':
#> 
#>     flatten
d <- tibble(
  id = 1:3,
  text = c("this is a string", "this is another string", "yet another string")
) 

jl <- d |> 
  transpose() |> 
  map_chr(toJSON) 

jl
#> [1] "{\"id\":[1],\"text\":[\"this is a string\"]}"      
#> [2] "{\"id\":[2],\"text\":[\"this is another string\"]}"
#> [3] "{\"id\":[3],\"text\":[\"yet another string\"]}"

I need text to be scalar. Desired output:

#> [1] "{\"id\":[1],\"text\":\"this is a string\"}"      
#> [2] "{\"id\":[2],\"text\":\"this is another string\"}"
#> [3] "{\"id\":[3],\"text\":\"yet another string\"}"
Solution

  • We may use auto_unbox = TRUE

    library(purrr)
library(jsonlite)
d |> 
  transpose() |> 
  map_chr(toJSON, auto_unbox = TRUE)

    -output

    [1] "{\"id\":1,\"text\":\"this is a string\"}" 
[2] "{\"id\":2,\"text\":\"this is another string\"}"
[3] "{\"id\":3,\"text\":\"yet another string\"}"