I inherited a function written either for an older version of R or SPlus
to draw a brace, "{", in a graph. It uses par("uin") to determine the
scaling of the
quarter circles that make up segments of the brace, but that setting
doesn't
exist in current R.
I'm guessing that, in the function below, ux, uy can be defined from
par("usr") and par("pin"), but maybe someone remembers what par("uin")
was supposed to refer to.
brace <- function (x1 = 0, y1 = 0, x2 = 0, y2 = 1, right = TRUE, rad = 0.2)
{
uin <- par("uin")
ux <- uin[1]
uy <- uin[2]
dx <- x2 - x1
dy <- y2 - y1
alpha <- atan(ux * dx, uy * dy)
scale <- sqrt((ux * dx)^2 + (uy * dy)^2)
if (scale > 5 * rad)
rad <- rad/scale
qcirc <- cbind(cos((0:10) * pi/20), sin((0:10) * pi/20))
qcircr <- cbind(cos((10:0) * pi/20), sin((10:0) * pi/20))
rot <- function(theta) t(cbind(c(cos(theta), sin(theta)),
c(-sin(theta), cos(theta))))
seg1 <- t(t(rad * qcirc %*% rot(-pi/2)) + c(0, rad))
seg4 <- t(t(rad * qcirc) + c(0, 1 - rad))
seg3 <- t(t((rad * qcircr) %*% rot(pi)) + c(2 * rad, 0.5 +
rad))
seg2 <- t(t((rad * qcircr) %*% rot(pi/2)) + c(2 * rad, 0.5 -
rad))
bra <- rbind(seg1, seg2, seg3, seg4)
if (!right)
bra <- bra %*% diag(c(-1, 1))
bra <- scale * bra %*% rot(-alpha)
bra <- bra %*% diag(c(1/ux, 1/uy))
bra <- t(t(bra) + c(x1, y1))
bra
}
--
Michael Friendly Email: friendly AT yorku DOT ca
Professor, Psychology Dept.
York University Voice: 416 736-5115 x66249 Fax: 416 736-5814
4700 Keele Street Web: http://www.datavis.ca
Toronto, ONT M3J 1P3 CANADA
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