stub to generalize angle in dev/

.Rbuildignore

@@ -19,3 +19,4 @@ docs/
 pkgdown/
 ^\.Rproj\.user$
 ^CRAN-SUBMISSION$
+dev/

R/util.R

@@ -42,10 +42,15 @@ formatNumbers <- function(x, fractions=FALSE, tol=sqrt(.Machine$double.eps)){
 	ret
 }
 
+# radians and degrees
 r2d <-function(r) r/pi * 180
 
 d2r <-function(d) pi*d / 180
 
+rad2deg <- function(rad) (rad * 180) / pi
+
+deg2rad <- function(deg) (deg * pi) / 180
+
 Fractions <- function(x, ...){
   opts <- getOption("fractions")
   if (is.null(opts)){

dev/angle.R

@@ -0,0 +1,40 @@
+# Generalize the angle function to allow angle(X, Y), where X, Y are matrices
+# and we want to calculate the angles between the columns of X, Y.
+# Or, angle(X), and want to calculate the angles between the columns of X
+
+angle <- function(x, y, degree = TRUE) {
+  if(missing(y)) y <- x
+  if(is.vector(x) && is.atomic(x)) {
+    theta <- acos(x %*% y / (len(x) * len(y)))
+  }
+  else {
+    theta <- acos(t(x) %*% y / outer(len(x), len(y)))
+  }
+  if(degree) theta <- r2d(theta)
+  theta
+}
+
+if(FALSE) {
+# one or two vectors
+x <- c(-2,1)
+y <- c(1,1)
+angle(x, y) # degrees
+angle(x, y, degree = FALSE) # radians
+angle(x)    # for one arg case
+
+# matrices
+
+X <- matrix(
+      c(1, 0, 1, 1, -2, 1),
+      ncol = 2,
+      byrow = TRUE)
+
+Y <- matrix(
+      c(1, 1, -1, -1),
+      ncol = 2,
+      byrow = TRUE)
+
+angle(X, Y)
+angle(X)
+
+}