R scripts => Data Structures:
a. Vectors –
Vectors are the most basic R
data objects and there are six types of atomic vectors. They are logical,
integer, double, complex, character and raw
Single Element Vector –
When you write just one value in
R, it becomes a vector of length 1 and belongs to one of the above vector
types.
# Atomic vector of type character.
print("abc");
# Atomic vector of type double.
print(12.5)
# Atomic vector of type integer.
print(63L)
# Atomic vector of type logical.
print(TRUE)
# Atomic vector of type complex.
print(2+3i)
# Atomic vector of type raw.
print(charToRaw('hello'))
When we execute the above code,
it produces the following result −
[1] "abc"
[1] 12.5
[1] 63
[1] TRUE
[1] 2+3i
[1] 68 65 6c 6c 6f
Multiple Elements Vector –
Using colon operator with numeric data #
Creating a sequence from 5 to 13. v <- 5:13
print(v)
# Creating a sequence from 6.6
to 12.6.
v <- 6.6:12.6
print(v)
# If the final element specified does not belong to
the sequence then it is discarded. v <- 3.8:11.4
print(v)
When we execute the above code,
it produces the following result –
[1]
5 6 7
8 9 10
11 12 13
[1]
6.6 7.6 8.6
9.6 10.6 11.6 12.6
[1]
3.8 4.8 5.8
6.8 7.8 8.8 9.8
10.8
Using sequence (Seq.) operator –
# Create vector with elements
from 5 to 9 incrementing by 0.4.
print(seq(5, 9, by = 0.4))
When we execute the above code,
it produces the following result –
[1] 5.0 5.4 5.8 6.2 6.6 7.0 7.4 7.8 8.2
8.6 9.0
Using the c() function –
The non-character values are
coerced to character type if one of the elements is a character.
# The logical and numeric values
are converted to characters.
s <- c('apple', 'red', 5, TRUE)
print(s)
When we execute the above code,
it produces the following result –
[1] "apple"
"red" "5" "TRUE"
b. Lists –
Lists are the R objects which
contain elements of different types like − numbers, strings, vectors and
another list inside it. A list can also contain a matrix or a function as its
elements. List is created using list() function
Creating a List –
Following is an example to
create a list containing strings, numbers, vectors and a logical values.
# Create a list containing strings, numbers, vectors
and a logical # values.
list_data <- list("Red",
"Green", c(21,32,11), TRUE, 51.23,
119.1) print(list_data)
When we execute the above code,
it produces the following result –
[[1]]
[1] "Red"
[[2]]
[1] "Green"
[[3]]
[1] 21 32 11
[[4]]
[1] TRUE
[[5]]
[1] 51.23
[[6]]
Naming List Elements –
The list elements can be given
names and they can be accessed using these names.
# 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)
When we execute the above code,
it produces the following result –
$`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"
$A_Inner_list[[2]]
[1] 12.3
Accessing List Elements
Elements of the list can be
accessed by the index of the element in the list. In case of named lists it can
also be accessed using the names.
We continue to use the list in
the above example –
# Create a list containing a
vector, a matrix and a list.
list_data <-
list(c("Jan","Feb","Mar"), matrix(c(3,9,5,1,-
2,8), nrow = 2),
list("green",12.3))
# Give names to the elements in
the list.
names(list_data) <- c("1st
Quarter", "A_Matrix", "A Inner list")
# Access the first element of the list. print(list_data[1])
# Access the thrid element. As
it is also a list, all its elements will be printed. print(list_data[3])
# Access the list element using
the name of the element.
print(list_data$A_Matrix)
When we execute the above code,
it produces the following result –
$`1st_Quarter`
[1] "Jan" "Feb"
"Mar"
$A_Inner_list
$A_Inner_list[[1]]
[1] "green"
$A_Inner_list[[2]]
[1] 12.3
[,1] [,2] [,3]
[1,]
3 5 -2
[2,]
9 1 8
Manipulating List Elements –
We can add, delete and update
list elements as shown below. We can add and delete elements only at the end of
a list. But we can update any element.
# 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")
# Add element at the end of the
list.
list_data[4] <- "New
element" print(list_data[4])
# Remove the last element.
list_data[4] <- NULL
# Print the 4th Element.
print(list_data[4])
# Update the 3rd Element.
list_data[3] <- "updated
element" print(list_data[3])
When we execute the above code,
it produces the following result –
[[1]]
[1] "New element"
$<NA>
NULL
$`A Inner list`
[1] "updated element"
Merging Lists –
You can merge many lists into
one list by placing all the lists inside one list() function.
# Create two lists.
list1 <- list(1,2,3)
list2 <-
list("Sun","Mon","Tue")
# Merge the two lists.
merged.list <- c(list1,list2)
# Print the merged list.
print(merged.list)
When we execute the above code,
it produces the following result –
[[1]]
[1] 1
[[2]]
[1] 2
[[3]]
[1] 3
[[4]]
[1] "Sun"
[[5]]
[1] "Mon"
[[6]]
[1] "Tue"
Converting List to Vector –
A list can be converted to a
vector so that the elements of the vector can be used for further manipulation.
All the arithmetic operations on vectors can be applied after the list is
converted into vectors. To do this conversion, we use the unlist() function. It
takes the list as input and produces a vector.
# Create lists.
list1 <- list(1:5) print(list1) list2 <-list(10:14)
print(list2)
# Convert the lists to vectors. v1
<- unlist(list1) v2 <- unlist(list2)
print(v1) print(v2)
# Now add the vectors
result <- v1+v2
print(result)
When we execute the above code,
it produces the following result –
[[1]]
[1] 1 2 3 4 5
[[1]]
[1] 10 11 12 13 14
[1] 1 2 3 4 5
[1] 10 11 12 13 14
[1] 11 13 15 17 19