Trying to turn a data frame into hierarchical json array using jsonlite in r

Question

I\'m trying to get my super-simple data frame into something a little more useful - a json array in this case. My data looks like

| V1        | V2        | V3                


        

Answer 1

Your data.frame cannot be directly written into that format. In order to get the desired json, firstly you need to turn your data.frame into this structure:

list(
     list(V1=list(id=<num>),
          results=list(
                       list(id=<num>),
                       list(id=<num>),
                       ...)),
     ...)

Here's a way to apply the transformation to your example data:

library(jsonlite)
# recreate your data.frame
DF <- 
data.frame(V1=c(717374788,429700970),
           V2=c(694405490, 420694891),
           V3=c(606978836,420694211),
           V4=c(578345907,420792447),
           V5=c(555450273,420670045))

# transform the data.frame into the described structure
idsIndexes <- which(names(DF) != 'V1')
a <- lapply(1:nrow(DF),FUN=function(i){ 
                             list(V1=list(id=DF[i,'V1']),
                                  results=lapply(idsIndexes,
                                                FUN=function(j)list(id=DF[i,j])))
                           })

# serialize to json
txt <- toJSON(a)
# if you want, indent the json
txt <- prettify(txt)