Parse JSON with R

Question

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 analyze data from the web. I imagine this is possible (and maybe even straightforward), but I am looking to parse JSON data that is publicly available on the web. I am not a programmer by any stretch, so any help and instruction you can provide will be greatly appreciated. Even if you point me to a basic working example, I probably can work through it.

Answer 1

RJSONIO from Omegahat is another package which provides facilities for reading and writing data in JSON format.

rjson does not use S4/S3 methods and so is not readily extensible, but still useful. Unfortunately, it does not used vectorized operations and so is too slow for non-trivial data. Similarly, for reading JSON data into R, it is somewhat slow and so does not scale to large data, should this be an issue.

Update (new Package 2013-12-03):

jsonlite : This package is a fork of the RJSONIO package. It builds on the parser from RJSONIO but implements a different mapping between R objects and JSON strings. The C code in this package is mostly from the RJSONIO Package, the R code has been rewritten from scratch. In addition to drop-in replacements for fromJSON and toJSON , the package has functions to serialize objects. Furthermore, the package contains a lot of unit tests to make sure that all edge cases are encoded and decoded consistently for use with dynamic data in systems and applications.

Answer 2

The jsonlite package is easy to use and tries to convert json into data frames.

Example:

library(jsonlite)

# url with some information about project in Andalussia
url <- 'https://api.stackexchange.com/2.2/badges?order=desc&sort=rank&site=stackoverflow'

# read url and convert to data.frame
document <- fromJSON(txt=url)

Answer 3

Here is the missing example

library(rjson)
url <- 'http://someurl/data.json'
document <- fromJSON(file=url, method='C')

Answer 4

The function fromJSON() in RJSONIO, rjson and jsonlite don't return a simple 2D data.frame for complex nested json objects.

To overcome this you can use tidyjson . It takes in a json and always returns a data.frame. It is currently not availble in CRAN, you can get it here: https://github.com/sailthru/tidyjson

Update: tidyjson is now available in cran, you can install it directly using install.packages("tidyjson")

Answer 5

For the record, rjson and RJSONIO do change the file type, but they don't really parse per se. For instance, I receive ugly MongoDB data in JSON format, convert it with rjson or RJSONIO, then use unlist and tons of manual correction to actually parse it into a usable matrix.

Answer 6

Try below code using RJSONIO in console

library(RJSONIO)
library(RCurl)


json_file = getURL("https://raw.githubusercontent.com/isrini/SI_IS607/master/books.json")

json_file2 = RJSONIO::fromJSON(json_file)

head(json_file2)