CODEWITHSUNDEEP
rmatrix
Jamie Warren
Jamie Warren

Reputation: 95

How to convert data set into a specific type of matrix? (RStudio)

I am currently trying to convert this data set of team scores:

      week AwayTeam AwayScore HomeTeam HomeScore
1    1        A         1        B         1
2    1        C         0        D         1
3    2        A         1        D         0
4    2        B         1        C         0
5    3        C         4        A         0
6    3        D         2        B         2

Into a matrix that looks something like this:

A = matrix(c(1,-1,0,0,
             0,0,1,-1,
             1,0,0,-1,
             0,1,-1,0,
             -1,0,1,0,
             0,-1,0,1),6,4,byrow = TRUE)

The rows of matrix A works as follows: "1" equals the away team, "-1" equals the home team, and "0" is the remaining space in each row. The first row of matrix A, therefore, is team A (away) versus team B (home).

If anyone could help convert this data into a matrix like this, it would be greatly appreciated.

Upvotes: 1

Views: 37

Answers (1)

ThomasIsCoding
ThomasIsCoding

Reputation: 101403

You can try the code below

v <- LETTERS[1:4]
A <- matrix(0,nrow = nrow(df),ncol = 4)
A[cbind(1:nrow(df),match(df$AwayTeam,v))] <- 1
A[cbind(1:nrow(df),match(df$HomeTeam,v))] <- -1

such that

> A
     [,1] [,2] [,3] [,4]
[1,]    1   -1    0    0
[2,]    0    0    1   -1
[3,]    1    0    0   -1
[4,]    0    1   -1    0
[5,]   -1    0    1    0
[6,]    0   -1    0    1

DATA

df <- structure(list(week = c(1L, 1L, 2L, 2L, 3L, 3L), AwayTeam = c("A", 
"C", "A", "B", "C", "D"), AwayScore = c(1L, 0L, 1L, 1L, 4L, 2L
), HomeTeam = c("B", "D", "D", "C", "A", "B"), HomeScore = c(1L, 
1L, 0L, 0L, 0L, 2L)), class = "data.frame", row.names = c("1", 
"2", "3", "4", "5", "6"))

Upvotes: 1

Related Questions