Write a command to increase or decrease the number of vertical splits - vim

Question

I usually have my Vim screen split into two vertical windows, each of which may be further horizontally split. Sometimes, I want to add or delete a vertical window. Is there a way to detect how many top-level vertical splits there are and add or remove vsplits as necessary?
For example, suppose my screen looks like this:
+--------+--------+
| | |
| | |
+--------+ |
| | |
| | |
| +--------+
| | |
+--------+--------+
I want :Columns 1 to give me
+--------+
| |
| |
+--------+
| |
| |
| |
| |
+--------+
by closing the two right-most windows.
I want :Columns 2 to do nothing, detecting that two columns are already open.
And I want :Columns 3 to give me
+--------+--------+--------+
| | | |
| | | |
+--------+ | |
| | | |
| | | |
| +--------+ |
| | | |
+--------+--------+--------+
I am fine if the function ignores vertical splits within horizontal splits. For example, if I had
+--------+
| |
| |
+---+----+
| | |
| | |
| | |
| | |
+---+----+
and I ran :Columns 2, I would get
+--------+--------+
| | |
| | |
+---+----+ |
| | | |
| | | |
| | | |
| | | |
+---+----+--------+

Answer 1

There is indeed a way, but it is involved; the first step is to count the currently-open vertical windows, and I don’t know of any built-in function that facilitates this. The working approach I found to it is basically to start at the first window (the top of the first — if not the entirety of the first — vertical split), and to then, using wincmd l, move to the next window to the right for as long as wincmd l moves to a new window, adding each to a count of open vertical windows including the first one. (I think this is what Gary Fixler referred to in the comments on the question.)
I started trying to write the code for posting here, and it grew to become larger than any function I would want to put in my ~/.vimrc, so I ended up turning it into a plugin which takes the above approach and provides the :Columns command; see Columcille (on vim.org at http://www.vim.org/scripts/script.php?script_id=4742.) The plugin also provides a command for similarly managing horizontal split windows: :Rows divides the current column (or the main window, if there are no open vertical splits) into the specified number of “rows.”