Org agenda - show items that are in any of a list of categories

Question

I have an org-mode file separated into multiple categories. I know I can create an agenda command that will show only items from one given category, like so:

("a" "Category A items" agenda ""
      ((org-agenda-category-filter-preset
        (quote
         ("+a")))))

and then only items from category A will show up in the custom agenda view.

How can I configure a custom view so it will show items from two specified categories (e.g. "A" and "B")?

Answer 1

You can do complex matching like this easily using org-super-agenda. Install the package with M-x packages-install org-super-agenda then load it using

(use-package org-super-agenda
  :config
  (org-super-agenda-mode t))

Then set the agenda groups to show things in CATEGORY A, things in CATEGORY B and finally discard anything else:

(add-to-list 'org-agenda-custom-commands
             '("a" "Category A or B" agenda ""
              ((org-super-agenda-groups
                '((:category ("A"))
                  (:category ("B"))
                  (:discard (:anything))
                  ))
                )))

Answer 2

You can add multiple filters to a single agenda item by making the type a list of matches.

("c" "Category A and B items" ((agenda "" (org-agenda-category-filter-preset
                                       (quote
                                        ("+a"))))
                           (agenda "" (org-agenda-category-filter-preset
                                       (quote
                                        ("+b"))))))

Look in the org manual for more details.