YouTipR Vector
Vectors are the most basic data type in R.
There are 6 types of atomic vectors: logical, integer, double, character, complex, and raw.
## Creating Vectors
Below we create single-element vectors, which can be any of the 6 types above:
## Example
# Character atomic vector
print("tutorial");
# Double atomic vector
print(12.5)
# Integer atomic vector
print(23L)
# Logical atomic vector
print(TRUE)
# Complex atomic vector
print(2+3i)
# Raw atomic vector
print(charToRaw('hello'))
Executing the above code outputs:
"tutorial" 12.5 23 TRUE 2+3i 68 65 6c 6c 6f
Below we create multi-element vectors, using the colon : operator between numbers:
## Example
# Create a series from 5 to 13
v <-5:13
print(v)
# Create a series from 6.6 to 12.6
v <-6.6:12.6
print(v)
# If the last element doesn't belong to the series, it's discarded
v <-3.8:11.4
print(v)
Executing the above code outputs:
5 6 7 8 9 10 11 12 13 6.6 7.6 8.6 9.6 10.6 11.6 12.6 3.8 4.8 5.8 6.8 7.8 8.8 9.8 10.8
We can also use the sequence operator **seq()** to create vectors.
Below we create a vector from 5 to 9 with increment 0.4:
print(seq(5, 9, by = 0.4))
Executing the above code outputs:
5.0 5.4 5.8 6.2 6.6 7.0 7.4 7.8 8.2 8.6 9.0
The c() function can convert non-character elements to character:
## Example
# Numbers and logical values will be converted to character type
s <-c('apple','red',5,TRUE)
print(s)
Executing the above code outputs:
"apple" "red" "5" "TRUE"
* * *
## Accessing Vector Elements
To access vector elements, use square brackets []. Index values start from 1 (different from other programming languages). If the index is negative, the element at that position will be removed. You can also use TRUE, FALSE, or 0 and 1.
## Example
# Access vector elements using index
t<-c("Sun","Mon","Tue","Wed","Thurs","Fri","Sat")
u <-t[c(2,3,6)]
print(u)
# Use logical index, TRUE means read, FALSE means don't read
v <-t[c(TRUE,FALSE,FALSE,FALSE,FALSE,TRUE,FALSE)]
print(v)
# The second and fifth elements will be removed
x <-t[c(-2,-5)]
print(x)
# Use 0/1 index, 1 means read, 0 means don't read
y <-t[c(0,0,0,0,0,0,1)]
print(y)
Executing the above code outputs:
"Mon" "Tue" "Fri" "Sun" "Fri" "Sun" "Tue" "Wed" "Fri" "Sat" "Sun"
* * *
## Vector Operations
We can perform addition, subtraction, multiplication, or division on two vectors of the same length. The result is also output as a vector.
## Example
# Create two vectors
v1 <-c(3,1,4,5,0,12)
v2 <-c(5,11,9,8,1,22)
# Addition
add.result<- v1+v2
print(add.result)
# Subtraction
sub.result<- v1-v2
print(sub.result)
# Multiplication
multi.result<- v1*v2
print(multi.result)
# Division
divi.result<- v1/v2
print(divi.result)
Executing the above code outputs:
8 12 13 13 1 34 -2 -10 -5 -3 -1 -10 15 11 36 40 0 264 0.60000000 0.09090909 0.44444444 0.62500000 0.00000000 0.54545455
### Recycling Vectors
If two vectors have different lengths, the shorter one will recycle its elements until it matches the length of the longer vector.
## Example
v1 <-c(1,8,7,5,0,12)
v2 <-c(5,6)
# V2 becomes c(5,6,5,6,5,6)
add.result<- v1+v2
print(add.result)
sub.result<- v1-v2
print(sub.result)
Executing the above code outputs:
6 14 12 11 5 18 -4 2 2 -1 -5 6
### Vector Sorting
We can use the sort() function to sort vectors:
## Example
v <-c(2,11,6,5,0,21, -7, 111)
# Sorting
sort.result<-sort(v)
print(sort.result)
# Set decreasing parameter to TRUE for descending order, default is FALSE for ascending order
revsort.result<-sort(v, decreasing = TRUE)
print(revsort.result)
# Sort character type
v <-c("Tutorial","Google","Zhihu","Facebook")
sort.result<-sort(v)
print(sort.result)
# Descending order
revsort.result<-sort(v, decreasing = TRUE)
print(revsort.result)
Executing the above code outputs:
-7 0 2 5 6 11 21 111 111 21 11 6 5 2 0 -7 "Facebook" "Google" "Tutorial" "Zhihu" "Zhihu" "Tutorial" "Google" "Facebook