which does the same thing without copying all the keys to an array or sorting one set of them for no reason. Actually, if your low on memory, avoiding that sort and the (re-)allocation of those arrays might help your performance.
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal?
"Science is about questioning the status quo. Questioning authority".
The "good enough" maybe good enough for the now, and perfection maybe unobtainable, but that should not preclude us from striving for perfection, when time, circumstance or desire allow.
.. builds a hash where the key is something like "a.b.c.d". .. The problem is the total for a.b.c needs to be a sum of all the categories beneath it a.b.c.* and thus the top level category is the sum of "a.*".