How to convert to a sf-object?

to_sf.R

# see also https://github.com/r-spatial/sf/issues/185#issuecomment-304093929

library(sf)
library(purrr)
library(jsonlite)
# devtools::install_github("ropensci/crul")
library(crul)

x <- HttpClient$new(url = "http://dati.mit.gov.it/catalog/api/action/datastore_search")
res <- x$get(query = list(resource_id="484e08bf-3e0d-4b89-81b5-407b80c5f5e8", limit=5))
res <- jsonlite::fromJSON(res$parse())
z <- res$result$records
w <- z$`Multipoint WGS84 EPSG:4386 Coordinates`

w

# [1] "[16.578441,40.669874]"                                                                                          
# [2] "[16.390963,39.752256]"                                                                                          
# [3] "[[15.229943,40.441221],[15.889952,40.516008]]"                                                                  
# [4] "[[13.565973,37.322554],[13.837775,37.371788],[13.672253,37.317606],[13.685218,37.422153],[13.750323,37.403225]]"
# [5] "[[11.903521,42.324303],[12.024773,42.311299]]"

# Apparently "single points" are not in the correct format
w[1] <- paste0("[", w[1], "]")
w[2] <- paste0("[", w[2], "]")

mm <- function(x) paste0('{"type":"MultiPoint","coordinates":', x, "}")

k <- map(w, mm) %>% 
       map(read_sf)

k[[1]]

# > k[[1]]
# Simple feature collection with 1 feature and 0 fields
# geometry type:  MULTIPOINT
# dimension:      XY
# bbox:           xmin: 16.57844 ymin: 40.66987 xmax: 16.57844 ymax: 40.66987
# epsg (SRID):    4326
# proj4string:    +proj=longlat +datum=WGS84 +no_defs
#                         geometry
# 1 MULTIPOINT (16.578441 40.66...