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NDSII histogram

Source: R/snow_or_ice.R
NDSII_hist.Rd

This function creates an NDSII histogram with a vertical line showing the selected threshold discriminating snow and ice.

Usage

NDSII_hist(NDSII, th, breaks = 64, stdev = 2)

Arguments

NDSII

SpatRaster. Normalized Difference Snow Ice Index (NDSII).

th

numeric. NDSII threshold to discriminate between snow and ice.

breaks

one of:

  • a vector giving the breakpoints between histogram cells,

  • a function to compute the vector of breakpoints,

  • a single number giving the number of cells for the histogram,

  • a character string naming an algorithm to compute the number of cells (see ‘Details’),

  • a function to compute the number of cells.

In the last three cases the number is a suggestion only; as the breakpoints will be set to pretty values, the number is limited to 1e6 (with a warning if it was larger). If breaks is a function, the x vector is supplied to it as the only argument (and the number of breaks is only limited by the amount of available memory).

stdev

numeric. Standard deviation cutoff value for histogram stretching.

See also

preproc(), snow_or_ice(), graphics::hist()

Examples

green <- system.file("extdata/athabasca_B03_20200911.tif", package = "SatRbedo")
nir <- system.file("extdata/athabasca_B8A_20200911.tif", package = "SatRbedo")
outline <- system.file("extdata/athabasca_outline.shp", package = "SatRbedo")
green <- preproc(grd = green, outline = outline)
nir <- preproc(grd = nir, outline = outline)
res <- snow_or_ice(green, nir)
NDSII_hist(res$NDSII, res$th, breaks = 16, stdev = 3)