Trim spectra from LUCAS database

The spectra from LUCAS database (ESDAC*) seem to come from a XDS  (VIS + NIR) instrument, and this instrument give two options when exporting the spectra (every 0.5 nm, and every 2 nm), the data comes in 0.5 nm, and that means that we have 4200  data poits per spectrum, and that means a huge spectra matrix.

We can trim the spectra keeping just the spectral data every two nanometers, so we will have the reflectance values from 400 to 2498 nm every 2nm, so we have a less heavy matrix of 1050 data points per spectrum. This fuction will give us the spectra like a NIR6500.

Just create a sequence to select one column of every four, and call that function (like in my case) "trim05to2":

dim(lucas_spain$spc)
 2604 4200

spec2nm <- trim05to2(lucas_spain$spc)

dim(spec2nm)
 2604 1050

*European Soil Data Centre (ESDAC), esdac.jrc.ec.europa.eu, European Commission, Joint Research Centre