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"}]

Whitener

Why do you think you want it in that format? jsonlint.com says it's not valid. – Blunderbuss

@doctorlove, I've update the json format I need to see. Thank you. – Whitener

Still not valid ;-) Parse error on line 20: ... 5, "value:"server5"}] ----------------------^ Expecting '}', ':', ',', ']' – Blunderbuss

@doctorlove, I missed ", updated. – Whitener

Better :-) Do consider using jsonlint.com just to check in future. – Blunderbuss

Answer 1

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.

Edmead

Thanks. And if we want split by row. library(rjson);library(dplyr);res1<-data.frame(id= c(1, 2, 3, 4, 5),server=c("server1", "server2", "server3", "server4", "server5"),y1=letters[1:5],y2=LETTERS[1:5]) with res1$JsonList<-lapply ( (unname( split( (res1 %>% select_at (vars(starts_with("y")))), 1:nrow(res1)) ) ), function(x) rjson::toJSON(x) ) and with res1 %>% select_at (vars(-starts_with("y"))) – Fouquiertinville

Answer 2

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"}]

Hanna

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) – Disturbing

Answer 3

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

Secretion

read_json and write_json are designed to read/write from disk. jsonlite::toJSON(res1) is still the correct answer for this question. – Carcanet

Answer 4

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"}]

Carcanet

Answer 5

library(jsonlite)
library(cat)

jasonRES1 <- jsonlite::toJSON(res1)
cat(jasonRES1)

Pelagianism

While this code may answer the question, providing additional context regarding why and/or how this code answers the question and how it differs from the previous similar will make it more useful for others in the future. Please consider updating your answer with some explanatory notes. Thanks – Mope