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))
}
# }