Data commit

Task/Spiral-matrix/R/spiral-matrix-1.r

@@ -0,0 +1,3 @@
+spiral <- function(n) matrix(order(cumsum(rep(rep_len(c(1, n, -1, -n), 2 * n - 1), n - seq(2 * n - 1) %/% 2))), n, byrow = T) - 1
+
+spiral(5)

Task/Spiral-matrix/R/spiral-matrix-2.r

@@ -0,0 +1,15 @@
+spiral_matrix <- function(n) {
+    spiralv <- function(v) {
+        n <- sqrt(length(v))
+        if (n != floor(n))
+            stop("length of v should be a square of an integer")
+        if (n == 0)
+            stop("v should be of positive length")
+        if (n == 1)
+            m <- matrix(v, 1, 1)
+        else
+            m <- rbind(v[1:n], cbind(spiralv(v[(2 * n):(n^2)])[(n - 1):1, (n - 1):1], v[(n + 1):(2 * n - 1)]))
+        m
+    }
+    spiralv(1:(n^2))
+}

Task/Spiral-matrix/R/spiral-matrix-3.r

@@ -0,0 +1,27 @@
+spiralMatrix <- function(n)
+{
+  spiral <- matrix(0, nrow = n, ncol = n)
+  firstNumToWrite <- 0
+  neededLength <- n
+  startPt <- cbind(1, 0)#(1, 0) is needed for the first call to writeRight to work. We need to start in row 1.
+  writingDirectionIndex <- 0
+  #These two functions select a collection of adjacent elements and replaces them with the needed sequence.
+  #This heavily uses R's vector recycling rules.
+  writeDown <- function(seq) spiral[startPt[1] + seq, startPt[2]] <<- seq_len(neededLength) - 1 + firstNumToWrite
+  writeRight <- function(seq) spiral[startPt[1], startPt[2] + seq] <<- seq_len(neededLength) - 1 + firstNumToWrite
+  while(firstNumToWrite != n^2)
+  {
+    writingDirectionIndex <- writingDirectionIndex %% 4 + 1
+    seq <- seq_len(neededLength)
+    switch(writingDirectionIndex,
+           writeRight(seq),
+           writeDown(seq),
+           writeRight(-seq),
+           writeDown(-seq))
+    if(writingDirectionIndex %% 2) neededLength <- neededLength - 1
+    max <- max(spiral)
+    firstNumToWrite <- max + 1
+    startPt <- which(max == spiral, arr.ind = TRUE)
+  }
+  spiral
+}