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Grid vector coordinates

matrix-gridVector.Rd

Creates rectangular grid coordinates from two vectors.

Usage

gridVector(x, y = NULL)

Arguments

x,y

numeric vectors

Details

The grid is obtained by pairing each element of y with all elements of x. The X and Y coordinates of the points are stored in separate vectors. This is convenient, for example, for plotting. It can be useful also for brute force optimisation or simulation.

If y is NULL, the default, then y = x.

Value

a list with two components, X and Y, giving the coordinates which span the bivariate grid.

See also

expand.grid

Examples

## a small grid vector with row and col transformations
gridVector(0:2)
#> $X
#> [1] 0 1 2 0 1 2 0 1 2
#> 
#> $Y
#> [1] 0 0 0 1 1 1 2 2 2
#> 
data.frame(gridVector(0:2))
#>   X Y
#> 1 0 0
#> 2 1 0
#> 3 2 0
#> 4 0 1
#> 5 1 1
#> 6 2 1
#> 7 0 2
#> 8 1 2
#> 9 2 2
do.call("rbind", gridVector(0:2))
#>   [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9]
#> X    0    1    2    0    1    2    0    1    2
#> Y    0    0    0    1    1    1    2    2    2

gridVector(0:2, 0:3)
#> $X
#>  [1] 0 1 2 0 1 2 0 1 2 0 1 2
#> 
#> $Y
#>  [1] 0 0 0 1 1 1 2 2 2 3 3 3
#> 

## grid over a unit square
gridVector((0:10)/10) # equivalently: gridVector((0:10)/10, (0:10)/10)
#> $X
#>   [1] 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.0 0.1 0.2 0.3 0.4 0.5 0.6
#>  [19] 0.7 0.8 0.9 1.0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.0 0.1 0.2
#>  [37] 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
#>  [55] 1.0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.0 0.1 0.2 0.3 0.4 0.5
#>  [73] 0.6 0.7 0.8 0.9 1.0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.0 0.1
#>  [91] 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
#> [109] 0.9 1.0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
#> 
#> $Y
#>   [1] 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.1 0.1 0.1 0.1 0.1 0.1
#>  [19] 0.1 0.1 0.1 0.1 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.3 0.3 0.3
#>  [37] 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4
#>  [55] 0.4 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.6 0.6 0.6 0.6 0.6 0.6
#>  [73] 0.6 0.6 0.6 0.6 0.6 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.8 0.8
#>  [91] 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9
#> [109] 0.9 0.9 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0
#>