Get an Array of Values into a Cell within a Dataframe Using Jsonlite Package in R

The jsonlite package in R is a powerful tool for working with JSON data. One common task when working with JSON data is extracting specific values from a JSON object and placing them in a data frame.

JSON: JavaScript Object Notation, is a lightweight data-interchange format that is easy for humans to read and write and easy for machines to parse and generate.

• jsonlite package: A package in R for working with JSON data. It provides flexible, robust, high-performance tools for working with JSON in R.
• data frame: Data frames are a popular way to store and manipulate data in R Programming Language, they are similar to tables in a relational database.

Steps to store an array of values in a cell

• First, you will need to install the jsonlite package if it is not already installed. You can do this by running the command “install.packages(“jsonlite”)” in the R console.
• Next, you will need to load the jsonlite package by running the command “library(jsonlite)” in the R console.
• Then, you will use the fromJSON() function to parse the JSON data into a dataframe.
• After that, you can extract the values you need using the $ operator or the square bracket notation.
• Finally, you can append the extracted values to a new dataframe or an existing one.

Store an Array of Values into a Cell using jsonlite

After loading the jsonlite package we will create some demo json_data. Now as we have a demo JSON dataset we can apply fromJSON function to that data.

R

# Loading jsonlite package
library(jsonlite)

# JSON data
json_data <- '{"name":"John",
               "age":30,
               "city":"New York"}'

# Convert JSON to data frame
df <- fromJSON(json_data)

# Extract 'name' value
name <- df$name

# Extract 'age' value
age <- df$age

# Create a new dataframe with extracted values
new_df <- data.frame(name, age)

# Print new dataframe
print(new_df)

Output:

  name age
1 John  30

Let’s look at one more a little complex example.

R

# Loading jsonlite package
library(jsonlite)

# Convert JSON to data frame
df <- data.frame(col1 = c("A", "B", "C"),
                 col2 = NA)

# generating an array
arr <- list(list(name = "John", age = 30),
            list(name = "Jane", age = 28))

# defining value
df[2, "col2"] <- toJSON(arr)

# printing output
df

Output:

Dataframe created using JSON data

Now let’s try to show an example with nested elements in the in the JSON data.

R

# loading jsonlite package
library(jsonlite)

# converting JSON to dataframe
df <- data.frame(col1 = c("A", "B", "C"),
                 col2 = NA)

# defining object
obj <- list(person = list(name = "John",
                          age = 30),
            location = list(city = "New York",
                            country = "USA"))

# assigning value
df[3, "col2"] <- toJSON(obj)

# printing output
df

Output:

Nested  JSON object