Mutate a Spectra* object by transforming the spectra values, and/or adding new or replacing existing attributes.
This function is very similar to transform but it executes the
transformations iteratively so that later transformations can use the
columns created by earlier transformations. Like transform, unnamed
components are silently dropped.
Either the spectra, and/or the attributes (if the .data inherits from
the SpectraDataFrame class) can be affected:
To
affect the spectra, one should use the nir placeholder, eg nir
= log(1/nir)
To affect the attributes of the object, the definitions
of new columns are simply given using attributes names, newAttribute =
1/sqrt(attribute)
Both spectra and attrbutes can be transformed in one command.
## S4 method for signature 'Spectra' mutate(.data, ...)
.data |
an object inheriting from the |
... |
named parameters giving definitions of new columns |
Pierre Roudier pierre.roudier@gmail.com, from code from Hadley Wickham
Hadley Wickham (2011). The Split-Apply-Combine Strategy for Data Analysis. Journal of Statistical Software, 40(1), 1-29. URL http://www.jstatsoft.org/v40/i01/.
# Loading example data data(australia) spectra(australia) <- sr_no ~ ... ~ 350:2500 # Modifying spectra m <- mutate(australia, nir = log1p(1/nir)) plot(m) # Modifying and creating attributes m <- mutate( australia, sqrt_carbon = sqrt(carbon), foo = clay + ph, nir = log1p(1/nir) ) plot(m)
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