Find an evenly spaced grid for x

makeraster() fits the data to the specified raster.

fitraster() tries different raster parameter and returns the raster that covers most of the x values: The differences between the values of x are calculated (possible step sizes). For each of those step sizes, different points are tried (until all points have been covered by a raster) and the parameter combination leading to the best coverage (i.e. most points on the grid) ist used.

Note that only differences between the sorted values of x are considered as step size.

makeraster(x, startx, d, newlevels, tol = 0.1)

fitraster(x, tol = 0.1)

Arguments

x	numeric to be fitted with a raster
startx	starting point ("origin") for calculation of the raster
d	step size of the raster
newlevels	levels of the raster
tol	tolerance for rounding to new levels: elements of x within tol of the distance between the levels of the new grid are rounded to the new grid point.

Value

list with elements

x

the values of x, possibly rounded to the raster values

levels

the values of the raster

Author

Claudia Beleites

Examples

x <- c(sample(1:20, 10), (0:5) + 0.5)
raster <- makeraster(x, x[1], 2)
raster
#> $x
#>  [1] 10.0  9.0  8.0 20.0 15.0  1.0 19.0 11.0  5.0 18.0  0.5  1.5  2.5  3.5  4.5
#> [16]  5.5
#> 
#> $levels
#> [1]  8 10 12 14 16 18 20
#> 
plot(x)
abline(h = raster$levels, col = "#00000040")

## unoccupied levels
missing <- setdiff(raster$levels, raster$x)
abline(h = missing, col = "red")

## points acutally on the raster
onraster <- raster$x %in% raster$levels
points(which(onraster), raster$x[onraster], col = "blue", pch = 20)

raster <- fitraster(x)
raster
#> $x
#>  [1] 10.0  9.0  8.0 20.0 15.0  1.0 19.0 11.0  5.0 18.0  0.5  1.5  2.5  3.5  4.5
#> [16]  5.5
#> 
#> $levels
#>  [1]  0.5  1.0  1.5  2.0  2.5  3.0  3.5  4.0  4.5  5.0  5.5  6.0  6.5  7.0  7.5
#> [16]  8.0  8.5  9.0  9.5 10.0 10.5 11.0 11.5 12.0 12.5 13.0 13.5 14.0 14.5 15.0
#> [31] 15.5 16.0 16.5 17.0 17.5 18.0 18.5 19.0 19.5 20.0
#> 
plot(x)
abline(h = raster$levels, col = "#00000040")

## unoccupied levels
missing <- setdiff(raster$levels, raster$x)
abline(h = missing, col = "red")

## points acutally on the raster
onraster <- raster$x %in% raster$levels
points(which(onraster), raster$x[onraster], col = "blue", pch = 20)

x <- c(sample(1:20, 10), (0:5) + 0.45)
raster <- fitraster(x)
raster
#> $x
#>  [1]  7.00 18.00  6.00 10.00  1.00 13.00  2.00 19.00 14.00  4.00  0.45  1.45
#> [13]  2.45  3.45  4.45  5.45
#> 
#> $levels
#>  [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19
#> 
plot(x)
abline(h = raster$levels, col = "#00000040")

## unoccupied levels
missing <- setdiff(raster$levels, raster$x)
abline(h = missing, col = "red")

## points acutally on the raster
onraster <- raster$x %in% raster$levels
points(which(onraster), raster$x[onraster], col = "blue", pch = 20)