Implementing a squarified treemap in javascript
I'm currently trying to implement a treemap algorithm in Javascript. More specifically the algorithm described in Squarified Treemaps. The pseudo code given looks like the following:
procedure squarify(list of real children, list of real row, real w)
begin
real c = head(children);
if worst(row, w) <= worst(row++[c], w) then
squarify(tail(children),row++[c], w)
else
layoutrow(row);
squarify(children,[], width());
fi
end
however my JavaScript looks like:
var c = children[0];
if (worst(row, w) >= worst(row.concat(c), w)) {
this.squarify(children.splice(1), row.concat(c), w);
} else {
layoutrow(row);
this.squarify(children, [], width());
}
As far as I can tell my code works correctly, but the inequality is the wrong way around. I'm assuming I'm overlooking something in my implementation, or is the inequality the wrong way around in the pseudo code? Thanks
You want to add c to the current row when doing so will improve the aspect ratio ie when
worst(row++[c], w) < worst(row, w)
I've recently committed a piece of code on github that implements the algorithm in TypeScript and includes ready-to-use JavaScript:
https://github.com/nicnguyen/treemap
If you're only interested in the layout algorithm, check out my squarify npm package. It returns the layout data only, leaving you free to render the result however you want.