diff options
| author | Xavier Morel <xmo@openerp.com> | 2012-03-05 12:08:13 +0100 |
|---|---|---|
| committer | Xavier Morel <xmo@openerp.com> | 2012-03-05 12:08:13 +0100 |
| commit | 06abe5aa3d7a79159b79e5d321cabca7e4f90f1a (patch) | |
| tree | c8df4bbfcc6b1c45f1026fc85950903725c8ffcc /addons/web_process/static/lib/dracula/dracula_algorithms.js | |
| parent | fc887bfb2f5e5985a68590017e4eac9202e3428a (diff) | |
[FIX] re-add Dracula removed in rev xmo@openerp.com-20120305103353-w8r6fk9cv8wjklts: turns out Process needs it
bzr revid: xmo@openerp.com-20120305110813-b00fhngx0e5p0efo
Diffstat (limited to 'addons/web_process/static/lib/dracula/dracula_algorithms.js')
| -rw-r--r-- | addons/web_process/static/lib/dracula/dracula_algorithms.js | 599 |
1 files changed, 599 insertions, 0 deletions
diff --git a/addons/web_process/static/lib/dracula/dracula_algorithms.js b/addons/web_process/static/lib/dracula/dracula_algorithms.js new file mode 100644 index 00000000000..0fbb0857fc8 --- /dev/null +++ b/addons/web_process/static/lib/dracula/dracula_algorithms.js @@ -0,0 +1,599 @@ +/* + * Various algorithms and data structures, licensed under the MIT-license. + * (c) 2010 by Johann Philipp Strathausen <strathausen@gmail.com> + * http://strathausen.eu + * + */ + + + +/* + Bellman-Ford + + Path-finding algorithm, finds the shortest paths from one node to all nodes. + + + Complexity + + O( |E| · |V| ), where E = edges and V = vertices (nodes) + + + Constraints + + Can run on graphs with negative edge weights as long as they do not have + any negative weight cycles. + + */ +function bellman_ford(g, source) { + + /* STEP 1: initialisation */ + for(var n in g.nodes) + g.nodes[n].distance = Infinity; + /* predecessors are implicitly null */ + source.distance = 0; + + step("Initially, all distances are infinite and all predecessors are null."); + + /* STEP 2: relax each edge (this is at the heart of Bellman-Ford) */ + /* repeat this for the number of nodes minus one */ + for(var i = 1; i < g.nodes.length; i++) + /* for each edge */ + for(var e in g.edges) { + var edge = g.edges[e]; + if(edge.source.distance + edge.weight < edge.target.distance) { + step("Relax edge between " + edge.source.id + " and " + edge.target.id + "."); + edge.target.distance = edge.source.distance + edge.weight; + edge.target.predecessor = edge.source; + } + //Added by Jake Stothard (Needs to be tested) + if(!edge.style.directed) { + if(edge.target.distance + edge.weight < edge.source.distance) { + g.snapShot("Relax edge between "+edge.target.id+" and "+edge.source.id+"."); + edge.source.distance = edge.target.distance + edge.weight; + edge.source.predecessor = edge.target; + } + } + } + step("Ready."); + + /* STEP 3: TODO Check for negative cycles */ + /* For now we assume here that the graph does not contain any negative + weights cycles. (this is left as an excercise to the reader[tm]) */ +} + + + +/* + Path-finding algorithm Dijkstra + + - worst-case running time is O((|E| + |V|) · log |V| ) thus better than + Bellman-Ford for sparse graphs (with less edges), but cannot handle + negative edge weights + */ +function dijkstra(g, source) { + + /* initially, all distances are infinite and all predecessors are null */ + for(var n in g.nodes) + g.nodes[n].distance = Infinity; + /* predecessors are implicitly null */ + + g.snapShot("Initially, all distances are infinite and all predecessors are null."); + + source.distance = 0; + /* set of unoptimized nodes, sorted by their distance (but a Fibonacci heap + would be better) */ + var q = new BinaryMinHeap(g.nodes, "distance"); + + /* pointer to the node in focus */ + var node; + + /* get the node with the smallest distance + as long as we have unoptimized nodes. q.min() can have O(log n). */ + while(q.min() != undefined) { + /* remove the latest */ + node = q.extractMin(); + node.optimized = true; + + /* no nodes accessible from this one, should not happen */ + if(node.distance == Infinity) + throw "Orphaned node!"; + + /* for each neighbour of node */ + for(e in node.edges) { + var other = (node == node.edges[e].target) ? node.edges[e].source : node.edges[e].target; + + if(other.optimized) + continue; + + /* look for an alternative route */ + var alt = node.distance + node.edges[e].weight; + + /* update distance and route if a better one has been found */ + if (alt < other.distance) { + + /* update distance of neighbour */ + other.distance = alt; + + /* update priority queue */ + q.heapify(); + + /* update path */ + other.predecessor = node; + g.snapShot("Enhancing node.") + } + } + } +} + + +/* All-Pairs-Shortest-Paths */ +/* Runs at worst in O(|V|³) and at best in Omega(|V|³) :-) + complexity Sigma(|V|²) */ +/* This implementation is not yet ready for general use, but works with the + Dracula graph library. */ +function floyd_warshall(g, source) { + + /* Step 1: initialising empty path matrix (second dimension is implicit) */ + var path = []; + var next = []; + var n = g.nodes.length; + + /* construct path matrix, initialize with Infinity */ + for(j in g.nodes) { + path[j] = []; + next[j] = []; + for(i in g.nodes) + path[j][i] = j == i ? 0 : Infinity; + } + + /* initialize path with edge weights */ + for(e in g.edges) + path[g.edges[e].source.id][g.edges[e].target.id] = g.edges[e].weight; + + /* Note: Usually, the initialisation is done by getting the edge weights + from a node matrix representation of the graph, not by iterating through + a list of edges as done here. */ + + /* Step 2: find best distances (the heart of Floyd-Warshall) */ + for(k in g.nodes){ + for(i in g.nodes) { + for(j in g.nodes) + if(path[i][j] > path[i][k] + path[k][j]) { + path[i][j] = path[i][k] + path[k][j]; + /* Step 2.b: remember the path */ + next[i][j] = k; + } + } + } + + /* Step 3: Path reconstruction, get shortest path */ + function getPath(i, j) { + if(path[i][j] == Infinity) + throw "There is no path."; + var intermediate = next[i][j]; + if(intermediate == undefined) + return null; + else + return getPath(i, intermediate) + .concat([intermediate]) + .concat(getPath(intermediate, j)); + } + + /* TODO use the knowledge, e.g. mark path in graph */ +} + +/* + Ford-Fulkerson + + Max-Flow-Min-Cut Algorithm finding the maximum flow through a directed + graph from source to sink. + + + Complexity + + O(E * max(f)), max(f) being the maximum flow + + + Description + + As long as there is an open path through the residual graph, send the + minimum of the residual capacities on the path. + + + Constraints + + The algorithm works only if all weights are integers. Otherwise it is + possible that the Ford–Fulkerson algorithm will not converge to the maximum + value. + + + Input + + g - Graph object + s - Source ID + t - Target (sink) ID + + + Output + + Maximum flow from Source s to Target t + + */ +/* + Edmonds-Karp + + Max-Flow-Min-Cut Algorithm finding the maximum flow through a directed + graph from source to sink. An implementation of the Ford-Fulkerson + algorithm. + + + Complexity + + O(|V|*|E|²) + + + Input + + g - Graph object (with node and edge lists, capacity is a property of edge) + s - source ID + t - sink ID + + */ +function edmonds_karp(g, s, t) { + +} + +/* + A simple binary min-heap serving as a priority queue + - takes an array as the input, with elements having a key property + - elements will look like this: + { + key: "... key property ...", + value: "... element content ..." + } + - provides insert(), min(), extractMin() and heapify() + - example usage (e.g. via the Firebug or Chromium console): + var x = {foo: 20, hui: "bla"}; + var a = new BinaryMinHeap([x,{foo:3},{foo:10},{foo:20},{foo:30},{foo:6},{foo:1},{foo:3}],"foo"); + console.log(a.extractMin()); + console.log(a.extractMin()); + x.foo = 0; // update key + a.heapify(); // call this always after having a key updated + console.log(a.extractMin()); + console.log(a.extractMin()); + - can also be used on a simple array, like [9,7,8,5] + */ +function BinaryMinHeap(array, key) { + + /* Binary tree stored in an array, no need for a complicated data structure */ + var tree = []; + + var key = key || 'key'; + + /* Calculate the index of the parent or a child */ + var parent = function(index) { return Math.floor((index - 1)/2); }; + var right = function(index) { return 2 * index + 2; }; + var left = function(index) { return 2 * index + 1; }; + + /* Helper function to swap elements with their parent + as long as the parent is bigger */ + function bubble_up(i) { + var p = parent(i); + while((p >= 0) && (tree[i][key] < tree[p][key])) { + /* swap with parent */ + tree[i] = tree.splice(p, 1, tree[i])[0]; + /* go up one level */ + i = p; + p = parent(i); + } + } + + /* Helper function to swap elements with the smaller of their children + as long as there is one */ + function bubble_down(i) { + var l = left(i); + var r = right(i); + + /* as long as there are smaller children */ + while(tree[l] && (tree[i][key] > tree[l][key]) || tree[r] && (tree[i][key] > tree[r][key])) { + + /* find smaller child */ + var child = tree[l] ? tree[r] ? tree[l][key] > tree[r][key] ? r : l : l : l; + + /* swap with smaller child with current element */ + tree[i] = tree.splice(child, 1, tree[i])[0]; + + /* go up one level */ + i = child; + l = left(i); + r = right(i); + } + } + + /* Insert a new element with respect to the heap property + 1. Insert the element at the end + 2. Bubble it up until it is smaller than its parent */ + this.insert = function(element) { + + /* make sure there's a key property */ + (element[key] == undefined) && (element = {key:element}); + + /* insert element at the end */ + tree.push(element); + + /* bubble up the element */ + bubble_up(tree.length - 1); + } + + /* Only show us the minimum */ + this.min = function() { + return tree.length == 1 ? undefined : tree[0]; + } + + /* Return and remove the minimum + 1. Take the root as the minimum that we are looking for + 2. Move the last element to the root (thereby deleting the root) + 3. Compare the new root with both of its children, swap it with the + smaller child and then check again from there (bubble down) + */ + this.extractMin = function() { + var result = this.min(); + + /* move the last element to the root or empty the tree completely */ + /* bubble down the new root if necessary */ + (tree.length == 1) && (tree = []) || (tree[0] = tree.pop()) && bubble_down(0); + + return result; + } + + /* currently unused, TODO implement */ + this.changeKey = function(index, key) { + throw "function not implemented"; + } + + this.heapify = function() { + for(var start = Math.floor((tree.length - 2) / 2); start >= 0; start--) { + bubble_down(start); + } + } + + /* insert the input elements one by one only when we don't have a key property (TODO can be done more elegant) */ + for(i in (array || [])) + this.insert(array[i]); +} + + + +/* + Quick Sort: + 1. Select some random value from the array, the median. + 2. Divide the array in three smaller arrays according to the elements + being less, equal or greater than the median. + 3. Recursively sort the array containg the elements less than the + median and the one containing elements greater than the median. + 4. Concatenate the three arrays (less, equal and greater). + 5. One or no element is always sorted. + TODO: This could be implemented more efficiently by using only one array object and several pointers. +*/ +function quickSort(arr) { + /* recursion anchor: one element is always sorted */ + if(arr.length <= 1) return arr; + /* randomly selecting some value */ + var median = arr[Math.floor(Math.random() * arr.length)]; + var arr1 = [], arr2 = [], arr3 = []; + for(var i in arr) { + arr[i] < median && arr1.push(arr[i]); + arr[i] == median && arr2.push(arr[i]); + arr[i] > median && arr3.push(arr[i]); + } + /* recursive sorting and assembling final result */ + return quickSort(arr1).concat(arr2).concat(quickSort(arr3)); +} + +/* + Selection Sort: + 1. Select the minimum and remove it from the array + 2. Sort the rest recursively + 3. Return the minimum plus the sorted rest + 4. An array with only one element is already sorted +*/ +function selectionSort(arr) { + /* recursion anchor: one element is always sorted */ + if(arr.length == 1) return arr; + var minimum = Infinity; + var index; + for(var i in arr) { + if(arr[i] < minimum) { + minimum = arr[i]; + index = i; /* remember the minimum index for later removal */ + } + } + /* remove the minimum */ + arr.splice(index, 1); + /* assemble result and sort recursively (could be easily done iteratively as well)*/ + return [minimum].concat(selectionSort(arr)); +} + +/* + Merge Sort: + 1. Cut the array in half + 2. Sort each of them recursively + 3. Merge the two sorted arrays + 4. An array with only one element is considered sorted + +*/ +function mergeSort(arr) { + /* merges two sorted arrays into one sorted array */ + function merge(a, b) { + /* result set */ + var c = []; + /* as long as there are elements in the arrays to be merged */ + while(a.length > 0 || b.length > 0){ + /* are there elements to be merged, if yes, compare them and merge */ + var n = a.length > 0 && b.length > 0 ? a[0] < b[0] ? a.shift() : b.shift() : b.length > 0 ? b.shift() : a.length > 0 ? a.shift() : null; + /* always push the smaller one onto the result set */ + n != null && c.push(n); + } + return c; + } + /* this mergeSort implementation cuts the array in half, wich should be fine with randomized arrays, but introduces the risk of a worst-case scenario */ + median = Math.floor(arr.length / 2); + var part1 = arr.slice(0, median); /* for some reason it doesn't work if inserted directly in the return statement (tried so with firefox) */ + var part2 = arr.slice(median - arr.length); + return arr.length <= 1 ? arr : merge( + mergeSort(part1), /* first half */ + mergeSort(part2) /* second half */ + ); +} + +/* Balanced Red-Black-Tree */ +function RedBlackTree(arr) { + +} + +function BTree(arr) { + +} + +function NaryTree(n, arr) { + +} + +/** + * Knuth-Morris-Pratt string matching algorithm - finds a pattern in a text. + * FIXME: Doesn't work correctly yet. + */ +function kmp(p, t) { + + /** + * PREFIX, OVERLAP or FALIURE function for KMP. Computes how many iterations + * the algorithm can skip after a mismatch. + * + * @input p - pattern (string) + * @result array of skippable iterations + */ + function prefix(p) { + /* pi contains the computed skip marks */ + var pi = [0], k = 0; + for(q = 1; q < p.length; q++) { + while(k > 0 && (p.charAt(k) != p.charAt(q))) + k = pi[k-1]; + + (p.charAt(k) == p.charAt(q)) && k++; + + pi[q] = k; + } + return pi; + } + + /* The actual KMP algorithm starts here. */ + + var pi = prefix(p), q = 0, result = []; + + for(var i = 0; i < t.length; i++) { + /* jump forward as long as the character doesn't match */ + while((q > 0) && (p.charAt(q) != t.charAt(i))) + q = pi[q]; + + (p.charAt(q) == t.charAt(i)) && q++; + + (q == p.length) && result.push(i - p.length) && (q = pi[q]); + } + + return result; +} + +/* step for algorithm visualisation */ +function step(comment, funct) { + //wait for input + //display comment (before or after waiting) +// next.wait(); + /* execute callback function */ + funct(); +} + +/** + * Curry - Function currying + * Copyright (c) 2008 Ariel Flesler - aflesler(at)gmail(dot)com | http://flesler.blogspot.com + * Licensed under BSD (http://www.opensource.org/licenses/bsd-license.php) + * Date: 10/4/2008 + * + * @author Ariel Flesler + * @version 1.0.1 + */ +function curry( fn ){ + return function(){ + var args = curry.args(arguments), + master = arguments.callee, + self = this; + + return args.length >= fn.length ? fn.apply(self,args) : function(){ + return master.apply( self, args.concat(curry.args(arguments)) ); + }; + }; +}; + +curry.args = function( args ){ + return Array.prototype.slice.call(args); +}; + +Function.prototype.curry = function(){ + return curry(this); +}; + +/** + * Topological Sort + * + * Sort a directed graph based on incoming edges + * + * Coded by Jake Stothard + */ +function topological_sort(g) { + //Mark nodes as "deleted" instead of actually deleting them + //That way we don't have to copy g + + for(i in g.nodes) + g.nodes[i].deleted = false; + + var ret = topological_sort_helper(g); + + //Cleanup: Remove the deleted property + for(i in g.nodes) + delete g.nodes[i].deleted + + return ret; +} +function topological_sort_helper(g) { + //Find node with no incoming edges + var node; + for(i in g.nodes) { + if(g.nodes[i].deleted) + continue; //Bad style, meh + + var incoming = false; + for(j in g.nodes[i].edges) { + if(g.nodes[i].edges[j].target == g.nodes[i] + && g.nodes[i].edges[j].source.deleted == false) { + incoming = true; + break; + } + } + if(!incoming) { + node = g.nodes[i]; + break; + } + } + + // Either unsortable or done. Either way, GTFO + if(node == undefined) + return []; + + //"Delete" node from g + node.deleted = true; + + var tail = topological_sort_helper(g); + + tail.unshift(node); + + return tail; +} |
