Guess Appropriate Ordering for Generalized Horizon Labels

This function makes an (educated) guess at an appropriate set of levels for generalized horizon labels using the median of horizon depth mid-points.

Usage

guessGenHzLevels(x, hz = GHL(x, required = TRUE))

Arguments

x: a SoilProfileCollection object
hz: name of horizon-level attribute containing generalized horizon labels, see details

Value

a list:

levels: a vector of levels sorted by median horizon depth mid-point
median.depths: a vector of median horizon mid-points

Details

This function is useful when groups of horizons have been generalized via some method other than generalize.hz. For example, it may be useful to generalize horizons using labels derived from slice depths. The default sorting of these labels will not follow a logical depth-wise sorting when converted to a factor. guessGenHzLevels does a good job of "guessing" the proper ordering of these labels based on median horizon depth mid-point.

Author

D.E. Beaudette

Examples


# load some example data
data(sp1, package='aqp')

# upgrade to SoilProfileCollection
depths(sp1) <- id ~ top + bottom

# generalize horizon names
n <- c('O', 'A', 'B', 'C')
p <- c('O', 'A', 'B', 'C')
sp1$genhz <- generalize.hz(sp1$name, n, p)

# note: levels are in the order in which originally defined:
levels(sp1$genhz)
#> [1] "O"        "A"        "B"        "C"        "not-used"

# generalize horizons by depth slice
s <- dice(sp1, c(5, 10, 15, 25, 50, 100, 150) ~ .)
#> dropping horizons with invalid depth logic, see `metadata(x)$removed.horizons`
#> filling gaps left by HzDepthLogicSubset
s$slice <- paste0(s$top, ' cm')
# not a factor
levels(s$slice)
#> NULL

# the proper ordering of these new labels can be guessed from horizon depths
guessGenHzLevels(s, 'slice')
#> $levels
#> [1] "5 cm"   "10 cm"  "15 cm"  "25 cm"  "50 cm"  "100 cm" "150 cm"
#> 
#> $median.depths
#>   5 cm  10 cm  15 cm  25 cm  50 cm 100 cm 150 cm 
#>    5.5   10.5   15.5   25.5   50.5  100.5  150.5 
#> 

# convert to factor, and set proper order
s$slice <- factor(s$slice, levels=guessGenHzLevels(s, 'slice')$levels)

# that is better
levels(s$slice)
#> [1] "5 cm"   "10 cm"  "15 cm"  "25 cm"  "50 cm"  "100 cm" "150 cm"