makeraster: makeraster

In hyperSpec: Work with Hyperspectral Data, i.e. Spectra + Meta Information (Spatial, Time, Concentration, ...)

Description

find an evenly spaced grid for x

Usage

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.

Details

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.

Value

list with elements

x	the values of x, possibly rounded to the raster values
levels	the values of the raster

Author(s)

Claudia Beleites

Examples

x <- c (sample (1:20, 10), (0 : 5) + 0.5)
raster <- makeraster (x, x [1], 2)
raster
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
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
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)

hyperSpec documentation built on Sept. 13, 2021, 5:09 p.m.