Measure a distance between two points on a plot using locator; the function checks par("plt") and par("usr") to try to ensure that the aspect ratio y/x is 1, that is that the units of measurement in both x and y are equivalent.
Usage
airdist(ann=FALSE)
Arguments
ann
annotate the plot with line measured and distance
Value
a list with members:
distdistance measured
coordscoordinates between which distance is measured