How can I change the installation folder for Melpa packages?

Question

I have just started using Melpa, and I installed the first package. The package though goes to the folder

~/Library/Preferences/Aquamacs Emacs/Pakcages/elpa/

but I would prefer if it went to my .emacs.d/packages folder.

Is there a way to do that or is it not advisable for some reason? If not advisable, is there a way to ensure that if I use another computer that I still have that package installed so that the configurations are the same?

This is what I put on my .emacs file to get Melpa working as per this answer

;; Package installation - MELPA
(require 'package) ;; You might already have this line
(add-to-list 'package-archives
             '("melpa" . "https://melpa.org/packages/"))
(when (< emacs-major-version 24)
  ;; For important compatibility libraries like cl-lib
  (add-to-list 'package-archives '("gnu" . "http://elpa.gnu.org/packages/")))
(package-initialize) ;; You might already have this line

Answer 1

You want to change the variable package-user-dir:

(setq package-user-dir "~/.emacs.d/packages")

Change this setting before calling (package-initialize) or anything involving loading or installing packages, but after (require 'package).

How I found this:

I use Helm, which makes it easy to search through Emacs's functions and variables. I called describe-variable with C-h v and searched for package dir, and the variable came up. Without Helm, I would use the command apropos-variable and search for the same thing.