From e60e40b21cbf1616cc7fab917e7b7a3c08c4cab1 Mon Sep 17 00:00:00 2001
From: Waldir Leoncio <w.l.netto@medisin.uio.no>
Date: Thu, 22 Dec 2022 10:41:26 +0100
Subject: [PATCH] Translated myintersect()

---
 R/myintersect.R | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/R/myintersect.R b/R/myintersect.R
index b2c19f1..e2e8f26 100644
--- a/R/myintersect.R
+++ b/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)
+}