Emacs: how to find that at least one windows was vertically split - emacs

Question

I don't know, how to write a function like this in elisp:
if(any window was split vertically)
return t;
else
return nil;
true:
|----------| |----------|----------|
| | | | |
| | | | |
|----------| |----------|----------|
false:
|--------| |--------|-------|
| | | | |
| | | | |
|--------| | |-------|
| | | | |
| | | | |
|--------| |--------|-------|
I found, that there is window-list function, that returns a list of all the windows. So, the algorithm should be like this:
(setq windows (window-list))
dolist(windows)
{
if($_->is_vertically_split())
{
return nil;
}
}
return t;
How can I determine, that this window is vertically split? It's height shouldn't be 100%.
Update
Using #lawlist answer I wrote the following, but it doesn't work (always returns nil):
(defun no-window-is-vertically-split ()
(let (windows (window-list)
(result nil))
(dolist (w windows)
(when (or
(window-in-direction 'above w)
(window-in-direction 'below w))
(setq result t)))
result))
(no-window-is-vertically-split)
Is it possible to break the dolist loop and just return the value, when 1-st split window is found?

Answer 1

You can use any of these to test whether there is a window above, below, left or right:
(window-in-direction 'above)
or
(window-in-direction 'below)
or
(window-in-direction 'left)
or
(window-in-direction 'right)
And here is an example using conditions -- just replace [... do something] with your preferred action:
(cond
((window-in-direction 'above)
[... do something])
((window-in-direction 'below)
[... do something])
((window-in-direction 'left)
[... do something])
((window-in-direction 'right)
[... do something]))
To test whether there is only one window, the following is useful:
(one-window-p t)
Here is a test similar to the call of the question, which is based upon the the test being performed from the selected window:
(if
(or
(window-in-direction 'above)
(window-in-direction 'below))
(message "There is either a window above or below the selected window.")
(message "There is are no windows above or below the selected window."))
EDIT (August 1, 2014):  Based on the updated question of the original poster, the following is an example of how to break the dolist loop and throw the result:
(defun no-window-is-vertically-split ()
(catch 'done
(let* (
result
(windows (window-list)))
(dolist (w windows)
(when (or
(window-in-direction 'above w)
(window-in-direction 'below w))
(setq result t)
(throw 'done result))))))

Answer 2

These two functions will detect horizontal and vertical splits:
(defun any-vertical-splits-p ()
"Return t if any windows have been split vertically."
(when (member nil (mapcar #'window-full-height-p (window-list))) t))
(defun any-horizontal-splits-p ()
"Return t if any windows have been split horizontally."
(when (member nil (mapcar #'window-full-width-p (window-list))) t))
I wasn't quite sure I knew what you meant in your diagram. Vertical and horizontal are used here as Emacs uses them with split-window-vertically and split-window-horizontally.