transect.im
Pixel Values Along a Transect
Extract the pixel values of a pixel image at each point along a linear transect.
Usage
transect.im(X, ..., from="bottomleft", to="topright",
click=FALSE, add=FALSE)Arguments
- X
A pixel image (object of class
"im").- …
Ignored.
- from,to
Optional. Start point and end point of the transect. Pairs of \((x,y)\) coordinates in a format acceptable to
xy.coords, or keywords"bottom","left","top","right","bottomleft"etc.- click
Optional. Logical value. If
TRUE, the linear transect is determined interactively by the user, who clicks two points on the current plot.- add
Logical. If
click=TRUE, this argument determines whether to perform interactive tasks on the current plot (add=TRUE) or to start by plottingX(add=FALSE).
Details
The pixel values of the image X along a line segment
will be extracted. The result is a function table ("fv" object)
which can be plotted directly.
If click=TRUE, then the user is prompted to click two points on
the plot of X. These endpoints define the transect.
Otherwise, the transect is defined by the endpoints
from and to. The default is a diagonal transect from
bottom left to top right of the frame.
Value
An object of class "fv" which can be plotted.
See Also
Examples
# NOT RUN {
Z <- density(redwood)
plot(transect.im(Z))
# }
# NOT RUN {
if(FALSE) {
plot(transect.im(Z, click=TRUE))
}
# }