aqp (version 1.18)

denormalize: Create a (redundant) horizon-level attribute from a site-level attribute

Description

Create a (redundant) horizon-level attribute from a site-level attribute. Specify a SoilProfileCollection and a site-level attribute from that SPC (by name) to recieve a vector of length equal to the number of horizons containing the site-level values. This vector is directly usable with the SoilProfileCollection horizon setter.

Usage

denormalize(obj, attr)

Arguments

obj

A SoilProfileCollection

attr

Site-level attribute name (character string) to denormalize to horizon.

Value

A vector of values of equal length to the number of rows in the horizon table of the input SPC.

Details

Denormalization is the process of trying to improve the read performance of a database, at the expense of losing some write performance, by adding redundant copies of data or by grouping data. Sometimes it is beneficial to have site-level attributes denormalized for grouping of horizon-level data in analyses. denormalize achieves this result for SoilProfileCollections.

Examples

# NOT RUN {
  data(sp1)
  
  # create a SoilProfileCollection from horizon data
  depths(sp1) <- ~ top + bottom
  
  # create random site-level attribute `sitevar` with a binary (0/1) outcome
  sp1$sitevar <- round(runif(length(sp1)))
  
  # use denormalize() to create a mirror of sitevar in the horizon table
  # name the attribute something different (e.g. `hz.sitevar`) to 
  # prevent collision with the site attribute
  # the attributes can have the same name but you will then need 
  # site() or horizons() to access explicitly
  sp1$hz.sitevar <- denormalize(sp1, 'sitevar')
  
  # compare number of profiles to number of sitevar assignments
  length(sp1)
  table(sp1$sitevar)
  
  # compare number of horizons to number of horizon-level copies of sitevar `hz.sitevar`
  nrow(sp1)
  table(sp1$hz.sitevar)
# }