Lists

LISTS

Creation

list_data <- list("Red", "Green", c(21,32,11), TRUE, 51.23, 119.1)
print(list_data)

## [[1]]
## [1] "Red"
## 
## [[2]]
## [1] "Green"
## 
## [[3]]
## [1] 21 32 11
## 
## [[4]]
## [1] TRUE
## 
## [[5]]
## [1] 51.23
## 
## [[6]]
## [1] 119.1

Naming Lists

# Create a list containing a vector, a matrix and a list.
list_data <- list(c("Jan","Feb","Mar"), matrix(c(3,9,5,1,-2,8), nrow = 2),
   list("green",12.3))

# Give names to the elements in the list.
names(list_data) <- c("1st Quarter", "A_Matrix", "A Inner list")

# Show the list.
print(list_data)

## $`1st Quarter`
## [1] "Jan" "Feb" "Mar"
## 
## $A_Matrix
##      [,1] [,2] [,3]
## [1,]    3    5   -2
## [2,]    9    1    8
## 
## $`A Inner list`
## $`A Inner list`[[1]]
## [1] "green"
## 
## $`A Inner list`[[2]]
## [1] 12.3

Accessing List Elements

# Create a list containing a vector, a matrix and a list.
list_data <- list(c("Jan","Feb","Mar"), matrix(c(3,9,5,1,-2,8), nrow = 2),
   list("green",12.3))

# Give names to the elements in the list.
names(list_data) <- c("1st Quarter", "A_Matrix", "A Inner list")

# Access

list_data[1]

## $`1st Quarter`
## [1] "Jan" "Feb" "Mar"

list_data[3]

## $`A Inner list`
## $`A Inner list`[[1]]
## [1] "green"
## 
## $`A Inner list`[[2]]
## [1] 12.3

# Using name element
list_data$A_Matrix

##      [,1] [,2] [,3]
## [1,]    3    5   -2
## [2,]    9    1    8

Manipulating List Elements

# Add element
list_data[4] <- 'New element'
list_data

## $`1st Quarter`
## [1] "Jan" "Feb" "Mar"
## 
## $A_Matrix
##      [,1] [,2] [,3]
## [1,]    3    5   -2
## [2,]    9    1    8
## 
## $`A Inner list`
## $`A Inner list`[[1]]
## [1] "green"
## 
## $`A Inner list`[[2]]
## [1] 12.3
## 
## 
## [[4]]
## [1] "New element"

# Removing element
list_data[4] <- NULL
list_data

## $`1st Quarter`
## [1] "Jan" "Feb" "Mar"
## 
## $A_Matrix
##      [,1] [,2] [,3]
## [1,]    3    5   -2
## [2,]    9    1    8
## 
## $`A Inner list`
## $`A Inner list`[[1]]
## [1] "green"
## 
## $`A Inner list`[[2]]
## [1] 12.3

# Update element
list_data[3] <- 'Updated element'
list_data

## $`1st Quarter`
## [1] "Jan" "Feb" "Mar"
## 
## $A_Matrix
##      [,1] [,2] [,3]
## [1,]    3    5   -2
## [2,]    9    1    8
## 
## $`A Inner list`
## [1] "Updated element"

Merging Lists

list1 <- list(1,2,3)
list2 <- list("Sun","Mon","Tue")

# Merge
merged.list <- c(list1, list2)
merged.list

## [[1]]
## [1] 1
## 
## [[2]]
## [1] 2
## 
## [[3]]
## [1] 3
## 
## [[4]]
## [1] "Sun"
## 
## [[5]]
## [1] "Mon"
## 
## [[6]]
## [1] "Tue"

List-to-Vector

list1 <- list(1:5)
print(list1)

## [[1]]
## [1] 1 2 3 4 5

list2 <-list(10:14)
print(list2)

## [[1]]
## [1] 10 11 12 13 14

# Converting lists to vectors
v1 <- unlist(list1)
v2 <- unlist(list2)

print(v1)

## [1] 1 2 3 4 5

print(v2)

## [1] 10 11 12 13 14

result <- v1 + v2
print(result)

## [1] 11 13 15 17 19