Re: array element subsetting

["S. Cowles" <scowles@xxxxxxxx>]

On Fri, 26 Mar 2010, Bart Schaefer wrote:

> Date: Fri, 26 Mar 2010 07:41:48 -0700
> From: Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>
> On Mar 26,  2:24am, S. Cowles wrote:
> } I am trying to figure out the correct syntax for constructing two
> } one-liner subsetting operations on arrays.  I have two objectives: 1)
> } select nth character from each array element, and 2) select nth element
> } within each array element.
> }
> } The array these methods operate upon is something simple such as:
> } a=(
> } ...
> } )
> (1) can be done with the (M) parameter flag and simple head/tail:
> 	print ${(M)a#?}

Simpler and more straightforward than backreferencing.  Thank you, Bart.

> (2) is more difficult to do without looping, because zsh doesn't
> support multidimensional arrays, so you have to force an eval step
> via the (e) flag:
> 	print ${(e):-'${${=:-'${^a}' ""}[2]}'}

I hadn't previously used the parameter expansion (e) or array creation 
${=...} methods.  The inline array element addition is new to me; I missed 
it in Peter's Manual, book, and the zshall man page.

Would it be worth considering adding a new subsection on Array Subsetting 
to the ARRAY PARAMETERS section of the man pages, just after the Subscript 
Parsing section and just prior to POSITIONAL PARAMETERS?