Create a matrix!
Matrices are similar to vectors, except they are in 2 dimensions! Let's create a 2x2 matrix "by hand" using matrix().
matrix(data = c(2, 3, 4, 5), nrow = 2, ncol = 2)
[,1] [,2]
[1,] 2 4
[2,] 3 5
Notice that the actual data for the matrix is passed in as a vector using c(), and is then converted to a matrix by specifying the number of rows and columns (also known as the dimensions).
Because the matrix is just created from a vector, the following is equivalent to the above code.
my_vector <- c(2, 3, 4, 5)
matrix(data = my_vector, nrow = 2, ncol = 2)
This is a part of the course
“Introduction to R for Finance”
Exercise instructions
my_vectorhas been defined for you.- Replace the
___to create a 3x3 matrix frommy_vector. - Print
my_matrix. - By default, matrices fill down each row. Run the code in the last example and note how the matrix fills across by using
byrow = TRUE. Compare this to the example given above.
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
# A vector of 9 numbers
my_vector <- c(1, 2, 3, 4, 5, 6, 7, 8, 9)
# 3x3 matrix
my_matrix <- matrix(data = ___, nrow = ___, ncol = ___)
# Print my_matrix
# Filling across using byrow = TRUE
matrix(data = c(2, 3, 4, 5), nrow = 2, ncol = 2, byrow = TRUE)