Useful Tricks for Matrix Manipulation (original) (raw)

Useful tricks for matrix manipulation

Installation

matricks is available on CRAN, so you can install it using simply:

If you rather want to install dev version, you can do it with devtools.

Usage

Main matricks functions are m and v, which provide convenient API to create matrices and vectors.
Why should we write:

matrix(c(5, 6, 7,
         8, 0, 9,
         3, 7, 1), nrow = 3, byrow = TRUE)
#>      [,1] [,2] [,3]
#> [1,]    5    6    7
#> [2,]    8    0    9
#> [3,]    3    7    1

if we can simply create such a matrix like that:

library(matricks)

m(5, 6, 7|
  8, 0, 9|
  3, 7, 1)
#>      [,1] [,2] [,3]
#> [1,]    5    6    7
#> [2,]    8    0    9
#> [3,]    3    7    1

v function is an useful shortcut for creating vertical vectors (single columns)

v(1,2,3)
#>      [,1]
#> [1,]    1
#> [2,]    2
#> [3,]    3
v(1:5)
#>      [,1]
#> [1,]    1
#> [2,]    2
#> [3,]    3
#> [4,]    4
#> [5,]    5

Setting values in easier with matricks

mat <- matrix(0, 3, 3)
set_values(mat, c(1, 2) ~ 0.5, c(3, 1) ~ 7)
#>      [,1] [,2] [,3]
#> [1,]    0  0.5    0
#> [2,]    0  0.0    0
#> [3,]    7  0.0    0