place_rule {pixelclasser} | R Documentation |
Places a line on the rgb plot
Description
A wrapper function for graphics::locator
that helps in creating rules.
Usage
place_rule(x_axis, y_axis, line_type = "f")
is.rule_points(x)
Arguments
x_axis |
a character string indicating the colour variable that
corresponds to the x axis, one of |
y_axis |
a character string indicating the colour variable that
corresponds to the y axis, one of |
line_type |
a character string indicating that the line is vertical
( |
x |
the R object being tested |
Details
This function calls graphics::locator
on a previously plotted
rgb plane to select two points with the mouse. Then it plots the line
joining them and returns an object of class "pixel_rule_object"
.
These objects are passed as parameters to pixel_rule()
to create
"pixel_rule"
objects.
True horizontal and vertical lines are difficult to create by hand. In
these cases, specifying "vertical"
or "horizontal"
(partial
match allowed, i.e. "h"
) will copy the appropriate coordinate value
from the first point to the second to make them the same. Note that this is
done after locator()
returns, so the plot will show the line joining
the original points, not the corrected ones. Use plot_rule()
to see
the corrected line.
Value
An object of class "pixel_rule_points"
containing these
elements:
-
x_axis
: a character string containing the colour variable selected asx
axis (one of "r, "g or "b"). -
y_axis
: a character string containing the colour variable selected asy
axis.
See Also
locator
, pixel_rule
,
plot_rule
, plot_rgb_plane
Examples
## Not run:
plot_rgb_plane("r", "g")
line01 <- place_rule("r", "g") # A "free" line
line02 <- place_rule("r", "g", "h") # A horizontal line
## End(Not run)