Interpolate/re-express spectral irradiance (or other spectral quantity) values at new wavelengths values. This is a low-level function operating on numeric vectors and called by higher level functions in the package, such as mathematical operators for classes for spectral data.
interpolate_spectrum(w.length.in, s.irrad, w.length.out, fill = NA, ...)a numeric vector of interpolated spectral values.
numeric vector of wavelengths (nm).
a numeric vector of spectral values.
numeric vector of wavelengths (nm).
a value to be assigned to out of range wavelengths.
additional arguments passed to spline().
Depending on the extent of the data natural spline interpolation or
linear interpolation are used. In the first case a call to
spline with method = "natural" is
used when 25 or fewer distinct wavelengths are available as input, or if
the wavelengths in the output are more than three times those in the input.
In the second case, a call to approx is
used.
If w.length.out is a numeric vector and length.out = NULL, it
directly gives the target wavelengths for interpolation. If it is
NULL, and length.out is an integer value evenly spaced
wavelength values covering the same wavelength range as in the input are
generated. If w.length.out is a numeric vector and length.out
is an integer value, length.out evenly spaced wavelengths covering
the wavelength range of w.length.out are generated.
Extrapolation is not supported.
With default fill = NA if the output exceeds the wavelength range of
the input, extrapolated values are filled with NA values. With
fill = NULL wavelengths outside the wavelength range of input data
are discarded. A numerical value can be also be provided as fill. While
interpolate_spectrum supports interpolation of a single numeric
vector, interpolate_wl applies, one at a time, interpolation to all
numeric columns found in x.
Other low-level functions operating on numeric vectors.:
as_energy(),
as_quantum_mol(),
calc_multipliers(),
div_spectra(),
energy_irradiance(),
energy_ratio(),
insert_hinges(),
integrate_xy(),
irradiance(),
l_insert_hinges(),
oper_spectra(),
photon_irradiance(),
photon_ratio(),
photons_energy_ratio(),
prod_spectra(),
s_e_irrad2rgb(),
split_energy_irradiance(),
split_photon_irradiance(),
subt_spectra(),
sum_spectra(),
trim_tails(),
v_insert_hinges(),
v_replace_hinges()
my.w.length <- 300:700
with(sun.data, interpolate_spectrum(w.length, s.e.irrad, my.w.length))
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