Bumped to 1.0.0 (and included an apparent fix for dimensions > 2).

Author: jaspervdg

.travis.yml

@@ -0,0 +1,8 @@
+language: node_js
+node_js:
+  - "0.8"
+  - "0.10"
+  - "0.12"
+before_install:
+  - npm install -g npm@">=1.4.6"
+sudo: false

README.md

@@ -2,38 +2,58 @@ ndarray-select
 ==============
 Finds the kth element in an ndarray in linear time with high probability.  This implementation is based on the [quick select algorithm](http://en.wikipedia.org/wiki/Quickselect) and mutates the array in place.
 
-# Example
+[![build status](https://secure.travis-ci.org/scijs/ndarray-select.png)](http://travis-ci.org/scijs/ndarray-select)
 
+## Examples
+### Single list
 ```javascript
 var pack = require("ndarray-pack")
 var ndselect = require("ndarray-select")
 
+var points = pack([0, 0, 1, 2.5, -1])
+
+//Find the median element in the list
+var median = ndselect(points, points.shape[0]>>1)
+
+console.log(median.get())
+```
+
+#### Output
+```
+0 2.5 -1
+```
+
+### Multiple lists
+It is also possible to select vectors (using lexicographical comparisons):
+```javascript
+var pack = require("ndarray-pack")
+var ndselect = require("ndarray-select")
 
 var points = pack([
   [0, 0, 1],
   [100, 0, 10],
   [50, 1, 10],
   [0, 2.5, -1],
-
-  // ... etc.
-
   [-1, -1, -1]
 ])
 
-
 //Find the median element in the list
 var median = ndselect(points, points.shape[0]>>1)
 
 console.log(median.get(0), median.get(1), median.get(2))
 ```
 
-# Install
-
-```sh
-npm install ndarray-select
+#### Output
+```
+0 2.5 -1
 ```
 
-# API
+## Install
+Install using [npm](https://www.npmjs.com/):
+
+    npm install ndarray-select
+
+## API
 
 ```javascript
 var ndselect = require("ndarray-select")
@@ -48,16 +68,16 @@ Selects the kth item from the ndarray `array` along the first axis of `array`.
 
 **Returns** An ndarray view of `array.pick(k)`
 
-**Note** This method modifies `array`.  After completion, the element at position `k` will be in sorted order, with all elements `<array.pick(k)` occuring before `k` and all elements `>array.pick(k)` after `k` in the list.
+**Note** This method modifies `array`. After completion, the element at position `k` will be in sorted order, with all elements `<array.pick(k)` occuring before `k` and all elements `>array.pick(k)` after `k` in the list.
 
 #### `ndselect.compile(order, useCompare, dtype)`
-Precompiles an optimized selection algorithm for an array with the given index order and datatype
+Precompiles an optimized selection algorithm for an array with the given index order and datatype.
 
 * `order` is the order of the ndarray
 * `useCompare` is a flag which if set uses a comparison function
 * `dtype` is the datatype of the array
 
 **Returns** An optimized `ndselect` function
 
-# Credits
+## License
 (c) 2014 Mikola Lysenko. MIT License

example/example.js

@@ -0,0 +1,37 @@
+"use strict"
+var pack = require("ndarray-pack")
+var ndselect = require("../select.js")
+
+// Vectors
+var points = pack([
+  [0, 0, 1],
+  [100, 0, 10],
+  [50, 1, 10],
+  [0, 2.5, -1],
+  [-1, -1, -1]
+])
+
+//Find the median element in the list
+var median = ndselect(points, points.shape[0]>>1)
+
+console.log(median.get(0), median.get(1), median.get(2))
+
+// Matrices
+var points = pack([
+  [[0, 0],[0, 1]],
+  [[0, 1],[0, 0]],
+  [[0, 0],[1, 0]],
+  [[1, 0],[0, 0]],
+  [[0, 1],[0, 1]]
+])
+/* Sorted:
+  [[0, 0],[0, 1]]
+  [[0, 1],[0, 0]]
+  [[0, 1],[0, 1]]
+  [[0, 0],[1, 0]]
+  [[1, 0],[0, 0]]
+*/
+//Find the median element in the list
+var median = ndselect(points, points.shape[0]>>1)
+
+console.log(require("ndarray-unpack")(median))

package.json

@@ -8,20 +8,21 @@
   },
   "dependencies": {},
   "devDependencies": {
-    "ndarray": "~1.0.11",
-    "ndarray-pack": "~1.0.1",
-    "ndarray-unpack": "~0.0.0",
-    "tape": "~2.12.3",
-    "dup": "0.0.0"
+    "ndarray": "^1.0.18",
+    "ndarray-pack": "^1.1.1",
+    "ndarray-unpack": "^1.0.0",
+    "tape": "^4.0.0",
+    "dup": "^1.0.0"
   },
   "scripts": {
     "test": "tape test/*.js"
   },
   "repository": {
     "type": "git",
-    "url": "git://github.com/mikolalysenko/ndarray-select.git"
+    "url": "git://github.com/scijs/ndarray-select.git"
   },
   "keywords": [
+    "scijs",
     "quick",
     "select",
     "median",
@@ -30,9 +31,11 @@
     "sort"
   ],
   "author": "Mikola Lysenko",
+  "contributors": [
+    "Jasper van de Gronde <[email protected]>"
+  ],
   "license": "MIT",
   "bugs": {
-    "url": "https://github.com/mikolalysenko/ndarray-select/issues"
-  },
-  "homepage": "https://github.com/mikolalysenko/ndarray-select"
+    "url": "https://github.com/scijs/ndarray-select/issues"
+  }
 }

select.js

@@ -76,9 +76,9 @@ function compileQuickSelect(order, useCompare, dtype) {
       INDEX(i) + "=0")
   }
   for(var i=1; i<dimension; ++i) {
-    if(i < dimension-1) {
-      vars.push(STEP_CMP(i) + "=(" + STRIDE(i) + "-" + SHAPE(i+1) + "*" + STRIDE(i+1) + ")|0",
-                STEP(order[i]) + "=(" + STRIDE(order[i]) + "-" + SHAPE(order[i+1]) + "*" + STRIDE(order[i+1]) + ")|0")
+    if(i > 1) {
+      vars.push(STEP_CMP(i) + "=(" + STRIDE(i) + "-" + SHAPE(i-1) + "*" + STRIDE(i-1) + ")|0",
+                STEP(order[i]) + "=(" + STRIDE(order[i]) + "-" + SHAPE(order[i-1]) + "*" + STRIDE(order[i-1]) + ")|0")
     } else {
       vars.push(STEP_CMP(i) + "=" + STRIDE(i),
                 STEP(order[i]) + "=" + STRIDE(order[i]))
@@ -162,19 +162,19 @@ function compileQuickSelect(order, useCompare, dtype) {
       PIVOT, "=(", RND, "()*(", HI, "-", LO, "+1)+", LO, ")|0;")
 
   //Partition array by pivot
-  swap(PIVOT, HI)
+  swap(PIVOT, HI) // Store pivot temporarily at the end of the array
 
   code.push(
-    PIVOT, "=", LO, ";",
+    PIVOT, "=", LO, ";", // PIVOT will now be used to keep track of the end of the interval of elements less than the pivot
     "for(", INDEX(0), "=", LO, ";",
       INDEX(0), "<", HI, ";",
-      INDEX(0), "++){")
-  compare(TMP, INDEX(0), HI)
+      INDEX(0), "++){") // Loop over other elements (unequal to the pivot), note that HI now points to the pivot
+  compare(TMP, INDEX(0), HI) // Lexicographical compare of element with pivot
   code.push("if(", TMP, "<0){")
-    swap(PIVOT, INDEX(0))
-    code.push(PIVOT, "++;")
+  swap(PIVOT, INDEX(0)) // Swap current element with element at index PIVOT if it is less than the pivot
+  code.push(PIVOT, "++;")
   code.push("}}")
-  swap(PIVOT, HI)
+  swap(PIVOT, HI) // Store pivot right after all elements that are less than the pivot (implying that all elements >= the pivot are behind the pivot)
 
   //Check pivot bounds
   code.push(

test/test.js

@@ -117,6 +117,13 @@ tape("ndarray-select", function(t) {
     [0,0,0,0,6],
   ])
 
+  verifyArray2D([
+    [0, 0, 1],
+    [100, 0, 10],
+    [50, 1, 10],
+    [0, 2.5, -1],
+    [-1, -1, -1]
+  ])
 
   ndselect(pack([
       [[0,0],