Measure spectral intensity at one wavenumber

Measures the intensity at one user-supplied wavenumber for every spectrum in an OpenSpecy object.

Usage

point_intensity(x, ...)

# Default S3 method
point_intensity(x, ...)

# S3 method for class 'OpenSpecy'
point_intensity(x, wavenumber, method = c("nearest", "linear"), ...)

Arguments

x

an OpenSpecy object.

wavenumber

a finite numeric scalar giving the wavenumber to measure.

method

character; use "nearest" to select the nearest measured point or "linear" to interpolate between adjacent measured points.

...

additional arguments passed to methods.

Value

A named numeric vector with one intensity per spectrum. Names and order match the columns of x$spectra. A non-finite selected or interpolated intensity is returned as NA for that spectrum. If the requested wavenumber is outside the shared axis, all values are returned as NA.

Details

This function measures a specified spectral point; it does not search for a local maximum. With method = "nearest", a point exactly halfway between two measured wavenumbers uses the lower wavenumber. Linear interpolation is confined to the two adjacent measured points and never extrapolates beyond the shared wavenumber axis.

See also

peak_ratio() for ratios between two point intensities and area_under_band() for measurements over a spectral region.

Examples

data("raman_hdpe")
point_intensity(raman_hdpe, wavenumber = 2880)
#> intensity 
#>       576 
point_intensity(raman_hdpe, wavenumber = 2880, method = "linear")
#> intensity 
#>  602.4639