R convert dataframe to JSON

r json dataframe rjson
user1471980 picture user1471980 · Aug 28, 2014 · Viewed 50.1k times · Source

I have a dataframe that I'd like to convert to json format:

my data frame called res1:

library(rjson)

structure(list(id = c(1, 2, 3, 4, 5), value = structure(1:5, .Label = c("server1", 
"server2", "server3", "server4", "server5"), class = "factor")), .Names = c("id", 
"value"), row.names = c(NA, -5L), class = "data.frame")

when I do:

toJSON(res1)

I get this:

{"id":[1,2,3,4,5],"value":["server1","server2","server3","server4","server5"]}

I need this json output to be like this, any ideas?

[{"id":1,"value":"server1"},{"id":2,"value":"server2"},{"id":3,"value":"server3"},{"id":4,"value":"server4"},{"id":5,"value":"server5"}]

Answer

nycdatawrangler picture nycdatawrangler · Jul 2, 2015

The jsonlite package exists to address exactly this problem: "A practical and consistent mapping between JSON data and R objects."

Its toJSON function provides this desired result with the default options:

library(jsonlite)
x <- toJSON(res1)
cat(x)

## [{"id":1,"value":"server1"},{"id":2,"value":"server2"},
## {"id":3,"value":"server3"},{"id":4,"value":"server4"},
## {"id":5,"value":"server5"}]

Related questions

R: Generic flattening of JSON to data.frame

This question is about a generic mechanism for converting any collection of non-cyclical homogeneous or heterogeneous data structures into a dataframe. This can be particularly useful when dealing with the ingestion of many JSON documents or with a large JSON …

Read More
Importing data from a JSON file into R

Is there a way to import data from a JSON file into R? More specifically, the file is an array of JSON objects with string fields, objects, and arrays. The RJSON Package isn't very clear on how to deal with …

Read More
Parse JSON with R

I am fairly new to R, but the more use it, the more I see how powerful it really is over SAS or SPSS. Just one of the major benefits, as I see them, is the ability to get and …

Read More