perpDists | R Documentation |
Computes off-transect (also called 'perpendicular') distances from measures of sighting distance and sighting angle.
perpDists(sightDist, sightAngle, data)
sightDist |
Character, name of column in |
sightAngle |
Character, name of column in |
data |
data.frame object containing sighting distance and sighting angle. |
If observers recorded sighting distance and sighting angle (as is often common in line transect surveys), use this function to convert
to off-transect distances, the required input data for F.dfunc.estim
.
A vector of off-transect (or perpendicular) distances. Units are the same as sightDist
.
Buckland, S.T., Anderson, D.R., Burnham, K.P. and Laake, J.L. 1993. Distance Sampling: Estimating Abundance of Biological Populations. Chapman and Hall, London.
dfuncEstim
# Load the example dataset of sparrow detections from package
data(sparrowDetectionData)
# Compute perpendicular, off-transect distances from the observer's sight distance and angle
sparrowDetectionData$perpDist <- perpDists(sightDist="sightdist", sightAngle="sightangle",
data=sparrowDetectionData)
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