I have a question about creating vectors. If I do a <- 1:10
, "a" has the values 1,2,3,4,5,6,7,8,9,10.
My question is how do you create a vector with specific intervals between its elements. For example, I would like to create a vector that has the values from 1 to 100 but only count in intervals of 5 so that I get a vector that has the values 5,10,15,20,...,95,100
I think that in Matlab we can do 1:5:100
, how do we do this using R?
I could try doing 5*(1:20)
but is there a shorter way? (since in this case I would need to know the whole length (100) and then divide by the size of the interval (5) to get the 20)
Use the code
x = seq(0,100,5) #this means (starting number, ending number, interval)
the output will be
[1] 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75
[17] 80 85 90 95 100
Usually, we want to divide our vector into a number of intervals. In this case, you can use a function where (a) is a vector and (b) is the number of intervals. (Let's suppose you want 4 intervals)
a <- 1:10
b <- 4
FunctionIntervalM <- function(a,b) {
seq(from=min(a), to = max(a), by = (max(a)-min(a))/b)
}
FunctionIntervalM(a,b)
# 1.00 3.25 5.50 7.75 10.00
Therefore you have 4 intervals:
1.00 - 3.25
3.25 - 5.50
5.50 - 7.75
7.75 - 10.00
You can also use a cut function
cut(a, 4)
# (0.991,3.25] (0.991,3.25] (0.991,3.25] (3.25,5.5] (3.25,5.5] (5.5,7.75]
# (5.5,7.75] (7.75,10] (7.75,10] (7.75,10]
#Levels: (0.991,3.25] (3.25,5.5] (5.5,7.75] (7.75,10]
Source: Stackoverflow.com