spectacles (version 0.5-4)

split: Split a Spectra* object using factors

Description

Splits a Spectra* object into groups using a factor, either a provided as a vector or as an attribute in the features of the object.

Usage

# S4 method for Spectra
split(x, f, drop = FALSE, ...)

Value

A list of objects of same class as x.

Arguments

x

Spectra object

f

either a vector of factors (for objects inheriting from Spectra), or the name or indice of an attribute in the data slot of an object inheriting from SpectraDataFrame

drop

ignored

...

further potential arguments passed to methods.

Author

Pierre Roudier

Details

This is an adaptation of the split function in the base package.

Examples

# Loading example data
data(australia)
spectra(australia) <- sr_no ~ ... ~ 350:2500

# On a Spectra object, we need to provide a vector of factors
# to split the object
s <- as(australia, 'Spectra')
# We make up some kind of factor to split the data. 
idx <- sample(letters[1:5], replace = TRUE, size = nrow(s)) # This is a vector
r <- split(s, idx)
str(r)

# On a SpectradataFrame object, we can also provide the name or index 
# of an attribute

# Generate some kind of factor
australia$fact <- sample(LETTERS[1:3], size = nrow(australia), replace = TRUE) 
r <- split(australia, 'fact')
str(r)

# A list is returned, and is thus ready for use with lapply, or any
# of the l*ply functions from the plyr package
lapply(r, nrow)