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index.js
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index.js
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var createGraph = require('ngraph.graph');
var createMiserables = require('miserables').create;
module.exports = factory(createGraph);
// Allow other developers have their own createGraph
module.exports.factory = factory;
function factory(createGraph) {
return {
ladder: ladder,
complete: complete,
completeBipartite: completeBipartite,
// these are synonyms
balancedBinTree: balancedBinTree,
balancedBinaryTree: balancedBinTree,
binaryTree: balancedBinTree,
binTree: balancedBinTree,
path: path,
circularLadder: circularLadder,
grid: grid,
grid3: grid3,
noLinks: noLinks,
wattsStrogatz: wattsStrogatz,
cliqueCircle: cliqueCircle,
miserables: createMiserables
};
function ladder(n) {
/**
* Ladder graph is a graph in form of ladder
* @param {Number} n Represents number of steps in the ladder
*/
if (!n || n < 0) {
throw new Error('Invalid number of nodes');
}
var g = createGraph(),
i;
for (i = 0; i < n - 1; ++i) {
g.addLink(i, i + 1);
// first row
g.addLink(n + i, n + i + 1);
// second row
g.addLink(i, n + i);
// ladder's step
}
g.addLink(n - 1, 2 * n - 1);
// last step in the ladder;
return g;
}
function circularLadder(n) {
/**
* Circular ladder with n steps.
*
* @param {Number} n of steps in the ladder.
*/
if (!n || n < 0) {
throw new Error('Invalid number of nodes');
}
var g = ladder(n);
g.addLink(0, n - 1);
g.addLink(n, 2 * n - 1);
return g;
}
function complete(n) {
/**
* Complete graph Kn.
*
* @param {Number} n represents number of nodes in the complete graph.
*/
if (!n || n < 1) {
throw new Error('At least two nodes are expected for complete graph');
}
var g = createGraph(),
i,
j;
for (i = 0; i < n; ++i) {
for (j = i + 1; j < n; ++j) {
if (i !== j) {
g.addLink(i, j);
}
}
}
return g;
}
function completeBipartite(n, m) {
/**
* Complete bipartite graph K n,m. Each node in the
* first partition is connected to all nodes in the second partition.
*
* @param {Number} n represents number of nodes in the first graph partition
* @param {Number} m represents number of nodes in the second graph partition
*/
if (!n || !m || n < 0 || m < 0) {
throw new Error('Graph dimensions are invalid. Number of nodes in each partition should be greater than 0');
}
var g = createGraph(),
i, j;
for (i = 0; i < n; ++i) {
for (j = n; j < n + m; ++j) {
g.addLink(i, j);
}
}
return g;
}
function path(n) {
/**
* Path graph with n steps.
*
* @param {Number} n number of nodes in the path
*/
if (!n || n < 0) {
throw new Error('Invalid number of nodes');
}
var g = createGraph(),
i;
g.addNode(0);
for (i = 1; i < n; ++i) {
g.addLink(i - 1, i);
}
return g;
}
function grid(n, m) {
/**
* Grid graph with n rows and m columns.
*
* @param {Number} n of rows in the graph.
* @param {Number} m of columns in the graph.
*/
if (n < 1 || m < 1) {
throw new Error('Invalid number of nodes in grid graph');
}
var g = createGraph(),
i,
j;
if (n === 1 && m === 1) {
g.addNode(0);
return g;
}
for (i = 0; i < n; ++i) {
for (j = 0; j < m; ++j) {
var node = i + j * n;
if (i > 0) { g.addLink(node, i - 1 + j * n); }
if (j > 0) { g.addLink(node, i + (j - 1) * n); }
}
}
return g;
}
function grid3(n, m, z) {
/**
* 3D grid with n rows and m columns and z levels.
*
* @param {Number} n of rows in the graph.
* @param {Number} m of columns in the graph.
* @param {Number} z of levels in the graph.
*/
if (n < 1 || m < 1 || z < 1) {
throw new Error('Invalid number of nodes in grid3 graph');
}
var g = createGraph(),
i, j, k;
if (n === 1 && m === 1 && z === 1) {
g.addNode(0);
return g;
}
for (k = 0; k < z; ++k) {
for (i = 0; i < n; ++i) {
for (j = 0; j < m; ++j) {
var level = k * n * m;
var node = i + j * n + level;
if (i > 0) { g.addLink(node, i - 1 + j * n + level); }
if (j > 0) { g.addLink(node, i + (j - 1) * n + level); }
if (k > 0) { g.addLink(node, i + j * n + (k - 1) * n * m ); }
}
}
}
return g;
}
function balancedBinTree(n) {
/**
* Balanced binary tree with n levels.
*
* @param {Number} n of levels in the binary tree
*/
if (n === undefined || n < 0) {
throw new Error('Invalid number of levels in balanced tree');
}
var g = createGraph(),
count = Math.pow(2, n),
level;
if (n === 0) {
g.addNode(1);
}
for (level = 1; level < count; ++level) {
var root = level,
left = root * 2,
right = root * 2 + 1;
g.addLink(root, left);
g.addLink(root, right);
}
return g;
}
function noLinks(n) {
/**
* Graph with no links
*
* @param {Number} n of nodes in the graph
*/
if (n < 0) {
throw new Error('Number of nodes should be >= 0');
}
var g = createGraph(), i;
for (i = 0; i < n; ++i) {
g.addNode(i);
}
return g;
}
function cliqueCircle(cliqueCount, cliqueSize) {
/**
* A circular graph with cliques instead of individual nodes
*
* @param {Number} cliqueCount number of cliques inside circle
* @param {Number} cliqueSize number of nodes inside each clique
*/
if (cliqueCount < 1) throw new Error('Invalid number of cliqueCount in cliqueCircle');
if (cliqueSize < 1) throw new Error('Invalid number of cliqueSize in cliqueCircle');
var graph = createGraph();
for (var i = 0; i < cliqueCount; ++i) {
appendClique(cliqueSize, i * cliqueSize)
if (i > 0) {
graph.addLink(i * cliqueSize, i * cliqueSize - 1);
}
}
graph.addLink(0, graph.getNodesCount() - 1);
return graph;
function appendClique(size, from) {
for (var i = 0; i < size; ++i) {
graph.addNode(i + from)
}
for (var i = 0; i < size; ++i) {
for (var j = i + 1; j < size; ++j) {
graph.addLink(i + from, j + from)
}
}
}
}
function wattsStrogatz(n, k, p, seed) {
/**
* Watts-Strogatz small-world graph.
*
* @param {Number} n The number of nodes
* @param {Number} k Each node is connected to k nearest neighbors in ring topology
* @param {Number} p The probability of rewiring each edge
* @see https://github.com/networkx/networkx/blob/master/networkx/generators/random_graphs.py
*/
if (k >= n) throw new Error('Choose smaller `k`. It cannot be larger than number of nodes `n`');
var random = require('ngraph.random').random(seed || 42);
var g = createGraph(), i, to;
for (i = 0; i < n; ++i) {
g.addNode(i);
}
// connect each node to k/2 neighbors
var neighborsSize = Math.floor(k/2 + 1);
for (var j = 1; j < neighborsSize; ++j) {
for (i = 0; i < n; ++i) {
to = (j + i) % n;
g.addLink(i, to);
}
}
// rewire edges from each node
// loop over all nodes in order (label) and neighbors in order (distance)
// no self loops or multiple edges allowed
for (j = 1; j < neighborsSize; ++j) {
for (i = 0; i < n; ++i) {
if (random.nextDouble() < p) {
var from = i;
to = (j + i) % n;
var newTo = random.next(n);
var needsRewire = (newTo === from || g.hasLink(from, newTo));
if (needsRewire && g.getLinks(from).length === n - 1) {
// we cannot rewire this node, it has too many links.
continue;
}
// Enforce no self-loops or multiple edges
while (needsRewire) {
newTo = random.next(n);
needsRewire = (newTo === from || g.hasLink(from, newTo));
}
var link = g.hasLink(from, to);
g.removeLink(link);
g.addLink(from, newTo);
}
}
}
return g;
}
}