cond.reclass: Test conditions and reclassify

In scapesClassification: User-Defined Classification of Raster Surfaces

Test conditions and reclassify

Description

Evaluate conditions for cells of a class and reclassify them if conditions are true.

Usage

cond.reclass(
  attTbl,
  ngbList = NULL,
  rNumb = FALSE,
  classVector,
  class,
  cond,
  reclass,
  peval = 1
)

Arguments

attTbl	data.frame, the attribute table returned by the function attTbl.
ngbList	list, the list of neighborhoods returned by the function ngbList. Only necessary if using an absolute neighborhood condition (see conditions).
rNumb	logic, the neighborhoods of the argument ngbList are identified by cell numbers (rNumb=FALSE) or by row numbers (rNumb=TRUE) (see ngbList). It is advised to use row numbers for large rasters.
classVector	numeric vector, defines the cells in the attribute table that have already been classified. See conditions for more information about class vectors.
class	numeric or numeric vector, indicates the class(es) for which conditions have to be evaluated.
cond	character string, the conditions a cell have to meet to be classified as indicated by the argument reclass. See conditions for more details.
reclass	numeric, the classification number to assign to all cells that meet the function conditions.
peval	numeric value between 0 and 1. If absolute neighborhood conditions are considered, test cells are classified if the number of positive evaluations is equal or greater than the percentage specified by the argument peval (see conditions).

Details

• The function evaluates the conditions of the argument cond for all cells in the classes of the argument class.

• Cells that meet the function conditions are re-classified as indicted by the argument reclass.

• Absolute test cell and neighborhood conditions can be used. The condition string can only include one neighborhood condition ('{}') (see conditions).

Value

Update classVector with the new cells that were classified by the function. See conditions for more information about class vectors.

See Also

conditions(), attTbl(), ngbList()

Examples

# DUMMY DATA
######################################################################################
library(scapesClassification)
library(terra)

# LOAD THE DUMMY RASTER
r <- list.files(system.file("extdata", package = "scapesClassification"),
                pattern = "dummy_raster\\.tif", full.names = TRUE)
r <- terra::rast(r)

# COMPUTE THE ATTRIBUTE TABLE
at <- attTbl(r, "dummy_var")

# COMPUTE THE LIST OF NEIGBORHOODS
nbs <- ngbList(r)

################################################################################
# RECLASS.NBS
################################################################################

# Compute an example class vector
cv <- cond.4.all(attTbl = at, cond = "dummy_var > 1", class = 1)

# Reclassify cells
cr <- cond.reclass(attTbl = at, ngbList = nbs,

                   # CLASS VECTOR COMPUTED WITH THE RULE "dummy_var > 1"
                   classVector = cv,

                   # CELLS TO RECLASSIFY HAVE THIS CLASS
                   class = 1,

                   # ABSOLUTE NEIGHBORHOOD CONDITION
                   cond = "dummy_var{} >= 5", peval = 1,

                   # NEW CLASSIFICATION NUMBER
                   reclass = 2)

# Convert class vectors to rasters
r_cv <- cv.2.rast(r, cv)
r_cr <- cv.2.rast(r, cr)

################################################################################
# PLOTS
################################################################################
oldpar <- par(mfrow = c(1,2))
m <- c(3, 1, 5, 4)

# 1.
r_cv[which(is.na(values(r_cv)))] <- 10
plot(r_cv, type="classes", mar=m, col=c("#78b2c4","#818792"), axes=FALSE,
     plg=list(x=1, y=1, cex=.80, title="Classes",legend=c("1", "NA")))
text(r); lines(r)
mtext(side=3, line=1, adj=0, cex=1, font=2, "1. COND.4.ALL")
mtext(side=3, line=0, adj=0, cex=0.9, "New class vector")
mtext(side=1, line=0, cex=1, adj=0, "Class: 1")
mtext(side=1, line=1, cex=1, adj=0, "Rule: 'dummy_var > 1'")

# 2.
r_cr[which(is.na(values(r_cr)))] <- 10
plot(r_cr, type="classes", mar=m, col=c("#78b2c4","#cfad89","#818792"), axes=FALSE,
     plg=list(x=1, y=1, cex=.80, title="Classes",legend=c("1", "reclass", "NA")))
text(r); lines(r)
mtext(side=3, line=1, adj=0, cex=1, font=2, "2. COND.RECLASS")
mtext(side=3, line=0, adj=0, cex=0.9, "Reclassify cells meeting conditions")
mtext(side=1, line=0, cex=1, adj=0, "Class: 2")
mtext(side=1, line=1, cex=1, adj=0, "Rule: 'dummy_var{ } >= 5'; peval = 1")
par(oldpar)

scapesClassification documentation built on March 18, 2022, 6:32 p.m.