prototype.batchTransform = function(input, data) {
log.debug(input, ['treeifying']);
var fields = this.param('groupby').field,
childField = this._output.children,
parentField = this._output.parent,
summary = [{name:'*', ops: ['values'], as: [childField]}],
aggrs = fields.map(function(f) {
return dl.groupby(f).summarize(summary);
}),
prev = this._internal || [], curr = [], i, n;
function level(index, node, values) {
var vals = aggrs[index].execute(values);
node[childField] = vals;
vals.forEach(function(n) {
n[parentField] = node;
curr.push(Tuple.ingest(n));
if (index+1 < fields.length) level(index+1, n, n[childField]);
else n[childField].forEach(function(c) { c[parentField] = n; });
});
}
var root = Tuple.ingest({});
root[parentField] = null;
curr.push(root);
level(0, root, data);
// update changeset with internal nodes
for (i=0, n=curr.length; i<n; ++i) {
input.add.push(curr[i]);
}
for (i=0, n=prev.length; i<n; ++i) {
input.rem.push(prev[i]);
}
this._internal = curr;
return input;
};
function tuple(gb, gv, ob, ov) {
var t = {_imputed: true}, i;
for (i=0; i<gv.length; ++i) t[gb[i]] = gv[i];
for (i=0; i<ov.length; ++i) t[ob[i]] = ov[i];
return Tuple.ingest(t);
}
vals.forEach(function(n) {
n[parentField] = node;
curr.push(Tuple.ingest(n));
if (index+1 < fields.length) level(index+1, n, n[childField]);
else n[childField].forEach(function(c) { c[parentField] = n; });
});