Slice Transect Into Shorter Sections
This function splits the transects in a ‘transect’ or ‘transectX’ traps object into multiple shorter sections. The function may also be applied directly to a capthist object based on transect data. This makes it easy to convert detection data collected along linear transects to point detection data (see Example).
snip(object, from = 0, by = 1000, length.out = NULL, keep.incomplete = TRUE)
object |
secr ‘traps’ or ‘capthist’ object based on transects |
from |
numeric starting posiiton (m) |
by |
numeric length of new transects (m) |
length.out |
numeric number of new transects, as alternative to ‘by’ |
keep.incomplete |
logical; if TRUE then initial or terminal sections of each original transect that are less than ‘by’ will be retained in the output |
If a positive length.out is specified, by will be computed as
(transectlength(object) - from) / length.out.
A ‘traps’ or ‘capthist’ object, according to the input.
If keep.incomplete == FALSE animals and detections from the
x <- seq(0, 4*pi, length = 41)
temptrans <- make.transect(x = x*100, y = sin(x)*300)
plot (snip(temptrans, by = 200), markvertices = 1)
## Not run:
## simulate some captures
tempcapt <- sim.capthist(temptrans, popn = list(D = 2,
buffer = 300), detectfn = 'HHN', binomN = 0,
detectpar = list(lambda0 = 0.5, sigma = 50))
## snip capture histories
tempCH <- snip(tempcapt, by = 20)
## collapse from 'transect' to 'count', discarding location within transects
tempCH <- reduce(tempCH, outputdetector = "count")
## fit secr model and examine H-T estimates of density
derived(secr.fit(tempCH, buffer = 300, CL = TRUE, trace = FALSE))
## also, may split an existing transect into equal lengths
## same result:
plot(snip(temptrans, by = transectlength(temptrans)/10),
markvertices = 1)
plot(snip(temptrans, length.out = 10), markvertices = 1)
## End(Not run)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.