Translated myintersect()

R/myintersect.R

@@ -1 +1,29 @@
-myintersect <- function(A, B) {}
+myintersect <- function(A, B) {
+  #  MYINTERSECT Intersection of two sets of positive integers (much faster than built - in intersect)
+  #  C <- myintersect(A, B)
+
+  A <- t(A)
+  B <- t(B)
+
+  if (is.null(A)) {
+    ma <- 0
+  } else {
+    ma <- max(A)
+  }
+
+  if (is.null(B)) {
+    mb <- 0
+  } else {
+    mb <- max(B)
+  }
+
+  if (ma == 0 | mb == 0) {
+    C <- vector()
+  } else {
+    # bits <- sparse(1, max(ma, mb))
+    bits <- zeros(1, max(ma, mb))
+    bits[A] <- 1
+    C <- B[as.logical(bits[B])]
+  }
+  return(C)
+}