Write JSON with multiple inputs in R - r

Question

I have a tibble and a list which I would like to write to a json file.
# A tibble: 2 x 12
i n c x
<chr> <chr> <chr> <chr>
1 NYC New York City United States LON,271;BOS,201
2 LON London United Kingdom NYC,270
I would like to replace the 'x' column with a list.
When I try to merge by the 'i' column with the element of the list, a lot of data is duplicated... :/
sample list:
$NYC
d p
1: LON 271
2: BOS 201
$LON
d p
1: NYC 270
I would like to end up with something that looks like this:
[
{
"i": "NYC",
"n": "New York City",
"c": "United States",
"C": "US",
"r": "Northern America",
"F": 66.256,
"L": -166.063,
"b": 94.42,
"s": 0.752,
"q": 4417,
"t": "0,0,0,0,0",
"x": [{
"d": "LON",
"p": 271
},
{
"d": "BOS",
"p": 201
}]
}
...
]
I'm thinking there should be a way to write the json file without merging the list and the tibble, or maybe there is a way to merge them in a ragged way ?
ah. I just had another idea. maybe I can convert my dataframe to a list then use Reduce to combine the lists...
http://www.sharecsv.com/s/2e1dc764430c6fe746d2299f71879c2e/routes-before-split.csv
http://www.sharecsv.com/s/b114e2cc6236bd22b23298035fb7e042/tibble.csv

Answer 1

We may do the following:
tbl
# A tibble: 1 x 13
# X i n c C r F L b s q t x
# <int> <fct> <fct> <fct> <fct> <fct> <dbl> <dbl> <dbl> <dbl> <int> <fct> <fct>
# 1 1 LON London United Kingd… GB Northern Eur… 51.5 -0.127 55.4 1.25 2088 0,0,1,3… AAL,15;AAR,15;A…
require(tidyverse)
tbl$x <- map(tbl$x, ~ strsplit(., ";|,")[[1]] %>%
{data.frame(d = .[c(T, F)], p = as.numeric(.[c(F, T)]))})
The latter two lines are a shortened version of this base R equivalent:
tbl$x <- lapply(tbl$x, function(r) {
tmp <- strsplit(r, ";|,")[[1]]
data.frame(d = tmp[seq(1, length(tmp), 2)],
p = as.numeric(tmp[seq(2, length(tmp), 2)]))
})
We go over the x column, split its elements by ; and , whenever possible, and then use the fact that the resulting odd elements will correspond do the d column in the desired outcome, and the even elements to the p column.
Output:
toJSON(tbl, pretty = TRUE)
[
{
"X": 1,
"i": "LON",
"n": "London",
"c": "United Kingdom",
"C": "GB",
"r": "Northern Europe",
"F": 51.508,
"L": -0.127,
"b": 55.43,
"s": 1.25,
"q": 2088,
"t": "0,0,1,3,1",
"x": [
{
"d": "AAL",
"p": 15
},
{
"d": "AAR",
"p": 15
},
{
"d": "ABZ",
"p": 48
}
]
}
]