Lists, Matrices, and Tables
Matrices
Rows and Columns
A matrix stores one data type in two dimensions. Column functions summarize values by column.
Program
Play the script to build a two-row matrix and choose the last column total.
matrices.R
grid <- matrix(1:6, nrow = 2)
column_totals <- colSums(grid)
last_total <- column_totals[3]
cat(last_total, "\n", sep = "")
matrix
`matrix(1:6, nrow = 2)` creates a rectangular numeric structure.
colSums
`colSums` adds values down each column.
dimension
Matrices keep row and column shape in `dim`.