R convert dataframe to JSON

Question

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"}]

Why do you think you want it in that format? http://jsonlint.com/ says it's not valid. — doctorlove, Aug 28 '14 at 14:03
@doctorlove, I've update the json format I need to see. Thank you. — user1471980, Aug 28 '14 at 14:14
Still not valid ;-) `Parse error on line 20: ... 5, "value:"server5"}] ----------------------^ Expecting '}', ':', ',', ']'` — doctorlove, Aug 28 '14 at 14:15
Better :-) Do consider using http://jsonlint.com/ just to check in future. — doctorlove, Aug 28 '14 at 14:19

nycdatawrangler · Answer 1 · 2015-07-03T21:51:16.650

59

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"}]

edited Jul 03 '15 at 21:51

answered Jul 02 '15 at 20:35

nycdatawrangler

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if you have the issue, that you have your values nested within an array, instead of a single value: use the option auto_unbox=TRUE in the toJSON function to unbox "value":["server1"] to "value": "server1". example command: toJSON(res1, pretty=TRUE, flatten=TRUE, auto_unbox=TRUE) – klickagent.ch Mar 25 '18 at 16:53

MrFlick · Accepted Answer · 2014-08-28T17:13:18.963

33

How about

library(rjson)
x <- toJSON(unname(split(res1, 1:nrow(res1))))
cat(x)
# [{"id":1,"value":"server1"},{"id":2,"value":"server2"},
# {"id":3,"value":"server3"},{"id":4,"value":"server4"},
# {"id":5,"value":"server5"}]

By using split() we are essentially breaking up the large data.frame into a separate data.frame for each row. And by removing the names from the resulting list, the toJSON function wraps the results in an array rather than a named object.

edited Aug 28 '14 at 17:13

answered Aug 28 '14 at 14:56

MrFlick

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Thanks. And if we want split by row. `library(rjson);library(dplyr);res1% select_at (vars(starts_with("y")))), 1:nrow(res1)) ) ), function(x) rjson::toJSON(x) ) ` and with `res1 %>% select_at (vars(-starts_with("y")))` – phili_b Jan 15 '20 at 13:56

score 5 · Answer 3 · answered Dec 30 '17 at 07:36

5

Now you can easily just call jsonlite::write_json() directly on the dataframe.

answered Dec 30 '17 at 07:36

Jared Wilber

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6

`read_json` and `write_json` are designed to read/write from disk. `jsonlite::toJSON(res1)` is still the correct answer for this question. – SymbolixAU Jul 18 '18 at 03:38

score 1 · Answer 4 · answered Jul 12 '19 at 01:25

1

You can also use library(jsonify)

jsonify::to_json( res1 )
# [{"id":1.0,"value":"server1"},{"id":2.0,"value":"server2"},{"id":3.0,"value":"server3"},{"id":4.0,"value":"server4"},{"id":5.0,"value":"server5"}]

answered Jul 12 '19 at 01:25

SymbolixAU

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R convert dataframe to JSON

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