Question

M <- matrix(1:4, nrow = 2, ncol = 2)

dimnames(m) <- list(c(""a"",""b""),c(""c"",""d""))
creates ____.

A) A 2x2 matrix with rows labeled "a" and "b" and columns labeled "c" and "d."
B) A 2x2 matrix with row names "a" and "b" and column names "c" and "d."
C) A 4x4 matrix with rows labeled "a" and "b" and columns labeled "c" and "d."
D) A vector with named elements "a," "b," "c," and "d."

Answer 1

The R code constructs a 2x2 matrix with numerical entries 1 to 4 and assigns row names "a" and "b" and column names "c" and "d", which is option B.

Step-by-step explanation:

The code snippet provided is written in R, a programming language used for statistical computing and graphics. The code creates a matrix using the matrix function and assigns it to the variable m.

This matrix is structured with 2 rows and 2 columns, filled with the numbers 1 to 4. Next, with the dimnames function, row and column names are set for the matrix. Row names are given as "a" and "b", and column names as "c" and "d". Thus, option B is the correct answer as it states that the code creates a 2x2 matrix with row names "a" and "b" and column names "c" and "d".

The code m <- matrix(1:4, nrow = 2, ncol = 2) creates a 2x2 matrix with the values from 1 to 4 arranged in a row-major order. The dimnames(m) <- list(c("a","b"), c("c","d")) statement assigns row names "a" and "b" and column names "c" and "d" to the matrix m. Therefore, the correct option is B) A 2x2 matrix with row names "a" and "b" and column names "c" and "d."