Re: [External] : Re: Any faster way to find frequency of words?

[Jean Louis]

* Drew Adams <drew.adams@oracle.com> [2021-05-10 17:03]:
> I use this, FWIW:
> 
> (defun hash-table-to-alist (hash-table)
>   "Create and return an alist created from HASH-TABLE.
> The order of alist entries is undefined, but it seems to be the same
> as the order of hash-table entries (which seems to be the order in
> which the entries were added to the table)."
>   (let ((al  ()))
>     (maphash (lambda (key val) (push (cons key val) al))
>              hash-table)
>     (nreverse al)))

That may be better, nicer.

I wonder if nreverse is really needed as function just returns some
data, is that data anyway destroyed thereafter?

Then I was also using reverse, I will take it out, as I don't think
there is any order in the hash, if I reverse it or not, it does not
matter.

(setq hash (make-hash-table))
(puthash 'Name "Jimmy" hash)
(puthash "City" "New York" hash)
(puthash "Brigade" "II" hash)

hash ⇒ #s(hash-table size 65 test eql rehash-size 1.5 rehash-threshold 0.8125 
data (Name "Jimmy" "City" "New York" "Brigade" "II"))

(puthash 'Name "Jimmy2" hash)

hash ⇒ #s(hash-table size 65 test eql rehash-size 1.5 rehash-threshold 0.8125 
data (Name "Jimmy2" "City" "New York" "Brigade" "II"))

I can see that hash keeps order of entries, but I don't believe
that is guaranteed. Visually it gives us the same order:

(hash-table-to-alist hash) ⇒ ((Name . "Jimmy2") ("City" . "New York") 
("Brigade" . "II"))

(setq alist (hash-table-to-alist hash)) ⇒ ((Name . "Jimmy2") ("City" . "New 
York") ("Brigade" . "II"))

(assoc 'Name alist) ⇒ (Name . "Jimmy2")

I just wonder if the order matters. It should not matter in hash,
alist, plist I guess.




-- 
Jean

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