pgirmess (version 1.6.9)

diag2edge: Computes the edge of a square from its diagonal

Description

Computes the edge of a square from its diagonal.

Usage

diag2edge(cordseg)

Arguments

cordseg

The diagonal coordinates. This can be a vector c(x1,y1,x2,y2), a 2 x 2 matrix or a data.frame (each line a coordinate)

Value

A 2x2 matrix of points coordinates

Details

The first point coordinates are the left top of the diagonal. The other coordinates computed are the other top of the square edge. Can be used e.g. to pass a square edge to pave in order to compute a sampling grid.

See Also

pave

Examples

# NOT RUN {
# diagonal sloping up
coord<-matrix(c(20,20,90,90),nr=2,byrow=TRUE)
plot(coord,type="n",xlim=c(0,100),ylim=c(0,110),asp=1)
lines(coord,lty=2)
# square edge
lines(diag2edge(coord),col="red")

# diagonal sloping down
coord<-matrix(c(20,90,90,20),nr=2,byrow=TRUE)
plot(coord,type="n",xlim=c(0,100),ylim=c(0,110),asp=1)
lines(coord,lty=2)
# square edge
lines(diag2edge(coord),col="red")

# diagonal vertical
coord<-matrix(c(20,90,20,20),nr=2,byrow=TRUE)
plot(coord,type="n",xlim=c(0,100),ylim=c(0,110),asp=1)
lines(coord,lty=2)
# square edge
lines(diag2edge(coord),col="red")

# }

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