# Dollar In R: Sign($) How To Use How does R code use Dollar$, and what does it mean? The operator $is used in R programming to access, add, update, and delete elements from the named list or dataframe. Follow this article to get helpful information. Table of Contents ## What is a Dollar in R? We can add, update, and delete elements and access variables in lists and data frames using the Dollar symbol ($) operator in R.

The examples that follow illustrate typical applications for this operator.

## Dollar in R: The Example

### Using Dollar to create a variable in a list

First, we need to create a list as shown below:

# Create a list
myList <- list(
a = c("A", "B", "C"),
b = c(12,20),
d = 10:20
)

# Print list
myList

Output

$a [1] "A" "B" "C"$b
[1] 12 20

$d [1] 10 11 12 13 14 15 16 17 18 19 20 Now, we will use the Dollar to create a variable in the list. # Create a list myList <- list( a = c("A", "B", "C"), b = c(12,20), d = 10:20 ) myList$e <- c("D","E","F")

# Print list
myList

Output

$a [1] "A" "B" "C"$b
[1] 12 20

$d [1] 10 11 12 13 14 15 16 17 18 19 20$e
[1] "D" "E" "F"

You can see that we have a new e-variable in this list.

### Using Dollar to access a variable in a list

If you want to access a specific variable in the list, you can use Dollar sign.

Following the code below:

# Create a list
myList <- list(
a = c("A", "B", "C"),
b = c(12,20),
d = 10:20
)

# Access b variable
myList$b Output [1] 12 20 ### Using Dollar to delete a column in a list We will access this variable and assign it a NULL value to delete a specific variable in a list. # Create a list myList <- list( a = c("A", "B", "C"), b = c(12,20), d = 10:20 ) # Delete b variable myList$b <- NULL

# Print list
myList

Output

$a [1] "A" "B" "C"$d
[1] 10 11 12 13 14 15 16 17 18 19 20

### Using Dollar to create a variable in a data frame

Similarly, we need to create a dataframe:

# Create a dataframe
df <- data.frame(
id= 1:5,
math = c(8,6,9,7,4),
english = c(10,5,7,5,8)
)

# Print data frame
df

Output

  id math english
1  1    8      10
2  2    6       5
3  3    9       7
4  4    7       5
5  5    4       8

Here, we will use Dollar sign to create a variable in this data frame.

# Create a dataframe
df <- data.frame(
id= 1:5,
math = c(8,6,9,7,4),
english = c(10,5,7,5,8)
)

df$physics <- c(9,7,6,9,8) # Print data frame df Output  id math english physics 1 1 8 10 9 2 2 6 5 7 3 3 9 7 6 4 4 7 5 9 5 5 4 8 8 ### Using Dollar to access a variable in a data frame For instance, the English variable in the data frame can be accessed using the code below: # Create a dataframe df <- data.frame( id= 1:5, math = c(8,6,9,7,4), english = c(10,5,7,5,8) ) # Access english variable df$english

Output

[1] 10  5  7  5  8

### Using Dollar to delete a column in a data frame

To delete a column in a data frame, we will access this column and assign it a NULL value.

# Create a dataframe
df <- data.frame(
id= 1:5,
math = c(8,6,9,7,4),
english = c(10,5,7,5,8)
)

# Delete english column
df\$english <- NULL

# Print data frame
df

Output

  id math
1  1    8
2  2    6
3  3    9
4  4    7
5  5    4