permutation-rank - npm Package Compare versions

Comparing version 0.0.0 to 0.1.0

index.js

 "use strict"
 
+var pool = require("typedarray-pool")
 var inverse = require("invert-permutation")
 
 function rank(permutation) {
-  switch(permutation.length) {
+  var n = permutation.length
+  switch(n) {
     case 0:
@@ -15,6 +17,10 @@ case 1:
   }
-  var p = permutation.slice(0)
-    , pinv = inverse(p)
-    , r = 0, s, t, i
-  for(i=p.length-1; i>0; --i) {
+  var p = pool.mallocUint32(n)
+  var pinv = pool.mallocUint32(n)
+  var r = 0, s, t, i
+  inverse(permutation, pinv)
+  for(i=0; i<n; ++i) {
+    p[i] = permutation[i]
+  }
+  for(i=n-1; i>0; --i) {
     t = pinv[i]
@@ -28,20 +34,38 @@ s = p[i]
   }
+  pool.freeUint32(pinv)
+  pool.freeUint32(p)
   return r
 }
 
-function unrank(n, r) {
+function unrank(n, r, p) {
   switch(n) {
     case 0:
+      if(p) { return p }
       return []
     case 1:
-      return [0]
+      if(p) {
+        p[0] = 0
+      } else {
+        return [0]
+      }
     case 2:
-      return r ? [0,1] : [1,0]
+      if(p) {
+        if(r) {
+          p[0] = 0
+          p[1] = 1
+        } else {
+          p[0] = 1
+          p[1] = 0
+        }
+        return p
+      } else {
+        return r ? [0,1] : [1,0]
+      }
     default:
       break
   }
-  var p = new Array(n)
-    , s, t, i, nf=1
+  p = p || new Array(n)
+  var s, t, i, nf=1
   p[0] = 0
-  for(i=1; i<p.length; ++i) {
+  for(i=1; i<n; ++i) {
     p[i] = i
@@ -48,0 +72,0 @@ nf = (nf*i)|0

package.json

 {
   "name": "permutation-rank",
-  "version": "0.0.0",
+  "version": "0.1.0",
   "description": "Ranks and unranks permutations",
@@ -10,3 +10,4 @@ "main": "index.js",
   "dependencies": {
-    "invert-permutation": "~0.0.0"
+    "invert-permutation": "~0.1.0",
+    "typedarray-pool": "~0.1.1"
   },
@@ -29,3 +30,4 @@ "devDependencies": {
     "compare",
-    "sort"
+    "sort",
+    "group"
   ],
@@ -32,0 +34,0 @@ "author": "Mikola Lysenko",

README.md

@@ -32,10 +32,19 @@ permutation-rank
 
+* `permutation` is an array encoding some permutation
 
-`require("permutation-rank").unrank(length, rank)`
+**Returns** An integer representing the ranked encoding of the permutation
+
+
+`require("permutation-rank").unrank(length, rank[, result])`
 --------------------------------------------------
 Computes a permutation from a rank order with the given length
 
+* `length` is the length of the permuation
+* `rank` is the index of the permutation
+* `result` is an optional argument which stores the result of the inversion
 
+**Returns** The permutation at the given rank
+
 Credits
 =======
 (c) 2013 Mikola Lysenko. MIT License

No alert changes

Improved metrics

Total package byte prevSize

5621

increased by51.43%

Number of package files

6

increased by20%

Lines of code

130

increased by22.64%

Number of lines in readme file

49

increased by22.5%

Worsened metrics

Dependency count

2

increased by100%

Dependency changes

• + Addedtypedarray-pool@~0.1.1

• + Addedbit-twiddle@0.0.2(transitive)

• + Addeddup@0.0.0(transitive)

• + Addedinvert-permutation@0.1.0(transitive)

• + Addedtypedarray-pool@0.1.2(transitive)

• - Removedinvert-permutation@0.0.0(transitive)

• Updatedinvert-permutation@~0.1.0