I have a vector with random numbers from 1-7 and I want to be able to determine the next number in the vector that follows the first value so that I can look for patterns and get a 7x7 matrix of values that shows how often a specific number follows another.
First number in rows and count of next number in columns.
I am trying to do this with a double loop currently, but am getting confused in the process.
For example-
Example vector-
floor(runif(10,1,8))
[1] 3 5 6 6 6 1 7 7 5 3
Answer-
1 2 3 4 5 6 7
1 0 0 0 0 0 0 1
2 NA NA NA NA NA NA NA
3 0 0 0 0 1 0 0
4 NA NA NA NA NA NA NA
5 0 0 1 0 0 1 0
6 1 0 0 0 0 3 0
7 0 0 0 0 1 0 1
Given a vector
v <- c(3, 5, 6, 6, 6, 1, 7, 7, 5, 3)
if you call table() on the vector you get a count of each element
table( v )
# v
# 1 3 5 6 7
# 1 2 2 3 2
If you call table() on mulitple vectors, you get a count for each combination of values.
Since you want to 'count' the number of times a value appears with the value next to it, you can call table() on the original vector, and the same vector shifted one-value to the right.
table( v[1:(length(v)-1)], v[2:length(v)] )
# y
# x 1 3 5 6 7
# 1 0 0 0 0 1
# 3 0 0 1 0 0
# 5 0 1 0 1 0
# 6 1 0 0 2 0
# 7 0 0 1 0 1
Which can be made more succinct (courtesy of Julius Vainora ) by
table(head(v, -1), tail(v, -1))
Note: the result doesn't include the NA rows you've got in your question.