Working with JSON Files in R Programming

JSON stands for JavaScript Object Notation. These files contain the data in human readable format, i.e. as text. Like any other file, one can read as well as write into the JSON files. In order to work with JSON files in R, one needs to install the "rjson"  package. The most common tasks done using JSON files under rjson packages are as follows:

• Install and load the rjson package in R console
• Create a JSON file
• Reading data from JSON file
• Write into JSON file
• Converting the JSON data into Dataframes
• Working with URLs 

Install and load the rjson package

One can install the rjson from the R console using the install.packages() command in the following way:

install.packages("rjson")

After installing rjson package one has to load the package using the library() function as follows:

library("rjson")

Creating a JSON file 

To create a JSON file, one can do the following steps:

• Copy the data given below into a notepad file or any text editor file. One can also create his own data as per the given format.

  { 
   "ID":["1","2","3","4","5"],
   "Name":["Mithuna","Tanushree","Parnasha","Arjun","Pankaj"],
   "Salary":["722.5","815.2","1611","2829","843.25"],
   "StartDate":["6/17/2014","1/1/2012","11/15/2014","9/23/2013","5/21/2013"],
   "Dept":["IT","IT","HR","Operations","Finance"]
  }

• Choose "all types" as the file type and save the file with .json extension.(Example: example.json)
• One must make sure that the information or data is contained within a pair or curly braces { } .

Reading a JSON file

In R, reading a JSON file is quite a simple task. One can extract and read the data of a JSON file very efficiently using the fromJSON() function. The fromJSON() function takes the JSON file and returns the extracted data from the JSON file in the list format by default.

Example:

Suppose the above data is stored in a file named example.json in the E drive. To read the file we must write the following code.

Output:

$ID
[1] "1" "2" "3" "4" "5"

$Name
[1] "Mithuna" "Tanushree" "Parnasha" "Arjun" "Pankaj"

$Salary
[1] "722.5" "815.2" "1611" "2829" "843.25"

$StartDate
[1] "6/17/2014" "1/1/2012" "11/15/2014" "9/23/2013" "5/21/2013"

$Dept
[1] "IT" "IT" "HR" "Operations" "Finance"

Writing into a JSON file 

One need to create a JSON Object using toJSON() function before he writes the data to a JSON file. To write into a JSON file use the write() function.

Example:

Output:

[[1]]
[1] "sunflower" "guava" "hibiscus"

[[2]]
[1] "flower" "fruit" "flower"

Converting the JSON data into Dataframes

In R, to convert the data extracted from a JSON file into a data frame one can use the as.data.frame() function. 

Example:

Output:

 ID Name Salary StartDate Dept
1 1 Mithuna 722.5 6/17/2014 IT
2 2 Tanushree 815.2 1/1/2012 IT
3 3 Parnasha 1611 11/15/2014 HR
4 4 Arjun 2829 9/23/2013 Operations
5 5 Pankaj 843.25 5/21/2013 Finance

Working with URLs 

One can take datasets from any websites and extract the data and use them. This can be done under any of two packages, namely RJSONIO and jsonlite.

Example:

Output:

[1] "LUCKY MART " "CUMBERLAND FARMS 1587 "
[3] "K&M SPORTS " "MASON&OLD RIDGE FARM "
[5] "HAMPTON CHUTNEY CO " "CM - HUTCHINSON "