Expand array into multiple elements per item?

Expand array into multiple elements per item?

[Benjamin R. Haskell]

Three questions:

1. How can I easily take:

     somelist=( 'a b' c 'd e' )

and get back:

     anotherlist=( -id 'a b' -id c -id 'd e' )

2. ...relatedly, I'm confused by the following:

      $ somelist=( 'a b' c 'd e' )
      $ print -l - $somelist
      a b
      c
      d e
(i)  $ print -l - $^somelist(e:'reply=( -id $REPLY )':)
      zsh: no matches found: a b(e:reply=( -id $REPLY ):)
(ii) $ print -l - $^somelist(Ne:'reply=( -id $REPLY )':)
      (...nothing printed...)
      $

Why does neither (i) nor (ii) work?

3. I thought I recalled a relatively recent addition to parameter 
expansion flags for just this use-case.  But I can't seem to find the 
flag in zsh-4.3.12 patchlevel 1.5346.  Still interested in the answer to 
the rest, regardless.

-- 
Best,
Ben

Re: Expand array into multiple elements per item?

[Anthony Charles]

Hi,

You can try this :
 print -l -- "-id "$^somelist

anotherlist=( "-id "$^somelist )

But I can't give you any answer for question 2 :/

-- 
Anthony CHARLES

On Tue, Sep 13, 2011 at 04:15:50AM -0400, Benjamin R. Haskell wrote:
> Three questions:
> 
> 1. How can I easily take:
> 
>     somelist=( 'a b' c 'd e' )
> 
> and get back:
> 
>     anotherlist=( -id 'a b' -id c -id 'd e' )
> 
> 2. ...relatedly, I'm confused by the following:
> 
>      $ somelist=( 'a b' c 'd e' )
>      $ print -l - $somelist
>      a b
>      c
>      d e
> (i)  $ print -l - $^somelist(e:'reply=( -id $REPLY )':)
>      zsh: no matches found: a b(e:reply=( -id $REPLY ):)
> (ii) $ print -l - $^somelist(Ne:'reply=( -id $REPLY )':)
>      (...nothing printed...)
>      $
> 
> Why does neither (i) nor (ii) work?
> 
> 3. I thought I recalled a relatively recent addition to parameter
> expansion flags for just this use-case.  But I can't seem to find
> the flag in zsh-4.3.12 patchlevel 1.5346.  Still interested in the
> answer to the rest, regardless.
> 

Re: Expand array into multiple elements per item?

[Benjamin R. Haskell]

On Tue, 13 Sep 2011, Anthony Charles wrote:

> Hi,
>
> You can try this :
> print -l -- "-id "$^somelist
>
> anotherlist=( "-id "$^somelist )
>
> But I can't give you any answer for question 2 :/

anotherlist should end up as I specified before:

     $ anotherlist=( -id 'a b' -id c -id 'd e' )

I.e. separate elements, but not just word-splitting everything:

     $ print -l - $^anotherlist
     -id     <-- separate
     a b     <-- kept as one argument
     -id     <-- separate
     c
     -id     <-- separate
     d e     <-- kept as one argument

With your suggestions the -id isn't a separate element:

     $ print -l - "-id "$^somelist
     -id a b
     -id c
     -id d e
     $ anotherlist=( "-id "$^somelist )
     $ print -l - $^anotherlist
     -id a b
     -id c
     -id d e

-- 
Best,
Ben

Re: Expand array into multiple elements per item?

[Peter Stephenson]

On Tue, 13 Sep 2011 04:15:50 -0400
"Benjamin R. Haskell" <zsh@benizi.com> wrote:

> Three questions:
> 
> 1. How can I easily take:
> 
>      somelist=( 'a b' c 'd e' )
> 
> and get back:
> 
>      anotherlist=( -id 'a b' -id c -id 'd e' )

anotherlist=({-id,${^somelist}})

> 2. ...relatedly, I'm confused by the following:
> 
>       $ somelist=( 'a b' c 'd e' )
>       $ print -l - $somelist
>       a b
>       c
>       d e
> (i)  $ print -l - $^somelist(e:'reply=( -id $REPLY )':)
>       zsh: no matches found: a b(e:reply=( -id $REPLY ):)
> (ii) $ print -l - $^somelist(Ne:'reply=( -id $REPLY )':)
>       (...nothing printed...)
>       $
> 
> Why does neither (i) nor (ii) work?

The main problem is that globbing flags rely on globbing; if there's no
matching file, it doesn't work.  You'd probably want "oN" in the
globbing flags to turn off sorting if you did have files.

> 3. I thought I recalled a relatively recent addition to parameter 
> expansion flags for just this use-case.  But I can't seem to find the 
> flag in zsh-4.3.12 patchlevel 1.5346.  Still interested in the answer to 
> the rest, regardless.

You might be thinking of the globbing flag, P.  If you did have files,
*(P:-id:) would have done what you wanted.  But you don't.  The actual
effect is a bit bizarre (turning off nomatch):

-id
a b(P:-id:)
-id
c(P:-id:)
-id
d e(P:-id:)

-- 
Peter Stephenson <pws@csr.com>            Software Engineer
Tel: +44 (0)1223 692070                   Cambridge Silicon Radio Limited
Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, UK


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Re: Expand array into multiple elements per item?

[Mikael Magnusson]

On 13 September 2011 10:57, Peter Stephenson <Peter.Stephenson@csr.com> wrote:
>> Why does neither (i) nor (ii) work?
>
> The main problem is that globbing flags rely on globbing; if there's no
> matching file, it doesn't work.  You'd probably want "oN" in the
> globbing flags to turn off sorting if you did have files.
>
>> 3. I thought I recalled a relatively recent addition to parameter
>> expansion flags for just this use-case.  But I can't seem to find the
>> flag in zsh-4.3.12 patchlevel 1.5346.  Still interested in the answer to
>> the rest, regardless.
>
> You might be thinking of the globbing flag, P.  If you did have files,
> *(P:-id:) would have done what you wanted.  But you don't.  The actual
> effect is a bit bizarre (turning off nomatch):
>
> -id
> a b(P:-id:)
> -id
> c(P:-id:)
> -id
> d e(P:-id:)

One fun thing you can do is use .(e,'reply=(foo bar baz)',) if you
want to use some other globbing flags on your data. It's not
applicable for this problem, at least I can't think of a way. I did
suggest it on irc once for sorting an array by the basename:

22:39 <offbyone> I want to sort this by basename so that I order the
elements in this pair of expansions asciibetically regardless of the
directory they're found in.
22:39 <offbyone> (so, for example, if I had A/02_something
B/01_something B/03_something, it'd come out as B/01_something
A/02_something B/03_something)
22:47 <Mikachu> a=( oneglob anotherglob )
22:47 <Mikachu> echo .(e:'reply=($a)':oe,'REPLY=$REPLY:t',)

It would be nice to have a similar mechanism for sorting arrays maybe :).

Oh wait, I just realized it does work, just do this:

% print -l - .(e:'reply=($somelist)':P:-id:)
-id
a b
-id
c
-id
d e

Obviously, this does qualify in the 'a bit of a hack' category. (And
yes, it does fail if $PWD is chmoded -x, maybe / is a safer bet.)

-- 
Mikael Magnusson

Re: Expand array into multiple elements per item?

[Benjamin R. Haskell]

On Tue, 13 Sep 2011, Peter Stephenson wrote:

> On Tue, 13 Sep 2011 04:15:50 -0400 "Benjamin R. Haskell" wrote:
>
>> Three questions:
>>
>> 1. How can I easily take:
>>      somelist=( 'a b' c 'd e' )
>>
>> and get back:
>>
>>      anotherlist=( -id 'a b' -id c -id 'd e' )
>
> anotherlist=({-id,${^somelist}})

Elegant.  I didn't think about brace expansion.  Thanks, this is what 
I'll use.


>> 2. ...relatedly, I'm confused by the following:
>>
>>      $ somelist=( 'a b' c 'd e' )
>> (i)  $ print -l - $^somelist(e:'reply=( -id $REPLY )':)
>>      zsh: no matches found: a b(e:reply=( -id $REPLY ):)
>> (ii) $ print -l - $^somelist(Ne:'reply=( -id $REPLY )':)
>>      (...nothing printed...)
>>      $
>>
>> Why does neither (i) nor (ii) work?
>
> The main problem is that globbing flags rely on globbing; if there's 
> no matching file, it doesn't work.

I think it's just the fact that the glob is expanded (and thus tested 
for the resultant filenames existing) before the qualifiers that trips 
me up, but yes: Don't use globs on non-files.  Makes sense.


>> 3. I thought I recalled a relatively recent addition to parameter 
>> expansion flags for just this use-case.  But I can't seem to find the 
>> flag in zsh-4.3.12 patchlevel 1.5346.  Still interested in the answer 
>> to the rest, regardless.
>
> You might be thinking of the globbing flag, P.  If you did have files,
> *(P:-id:) would have done what you wanted.  But you don't.  The actual
> effect is a bit bizarre (turning off nomatch):
>
> -id
> a b(P:-id:)
> -id
> c(P:-id:)
> -id
> d e(P:-id:)

Interesting.  Yes.  'P' was the flag I failed to find.

-- 
Thanks,
Ben

Re: Expand array into multiple elements per item?

[Benjamin R. Haskell]

On Tue, 13 Sep 2011, Mikael Magnusson wrote:

> On 13 September 2011 10:57, Peter Stephenson wrote:
>>> Why does neither (i) nor (ii) work?
>>
>> The main problem is that globbing flags rely on globbing; if there's 
>> no matching file, it doesn't work. [...]
>>
>
> One fun thing you can do is use .(e,'reply=(foo bar baz)',) if you 
> want to use some other globbing flags on your data. It's not 
> applicable for this problem, at least I can't think of a way. I did 
> suggest it on irc once for sorting an array by the basename:
>
> 22:39 <offbyone> I want to sort this by basename so that I order the 
> elements in this pair of expansions asciibetically regardless of the 
> directory they're found in.
> 22:39 <offbyone> (so, for example, if I had A/02_something 
> B/01_something B/03_something, it'd come out as B/01_something 
> A/02_something B/03_something)
> 22:47 <Mikachu> a=( oneglob anotherglob )
> 22:47 <Mikachu> echo .(e:'reply=($a)':oe,'REPLY=$REPLY:t',)
>
> It would be nice to have a similar mechanism for sorting arrays maybe :).

+1.


> Oh wait, I just realized it does work, just do this:
>
> % print -l - .(e:'reply=($somelist)':P:-id:)
> -id
> a b
> -id
> c
> -id
> d e
>
> Obviously, this does qualify in the 'a bit of a hack' category. (And 
> yes, it does fail if $PWD is chmoded -x, maybe / is a safer bet.)

Cool.  Nice hack.

-- 
Best,
Ben

Re: Expand array into multiple elements per item?

[Oliver Kiddle]

On 13 Sep, "Benjamin R. Haskell" wrote:
> > You can try this :
> > print -l -- "-id "$^somelist
> 
> anotherlist should end up as I specified before:
> 
>      $ anotherlist=( -id 'a b' -id c -id 'd e' )
> 
> I.e. separate elements, but not just word-splitting everything:

If you join the list up and then re-split it, it might work:
  print -l -- ${(0)${(pj:\0:):--id$'\0'$a}}

Oliver