need to assign/edit values in multidimensional associative arrays

[Golf Nut]

I am finding that altering and affecting values in elements in
multidimensiona l arrays is a huge pain in the ass. I cannot seem to find a
consistent way to assign values to arrays. Foreach would clearly be the most
efficient way to do it, but it only works on a copy of the original array
and not the original (which is counter intuitive in my estimation). Using
each doesn't work consistently either. Not only that, it's unduly complex
for multidimensiona l arrays that are more than 3 dimensions. For example,
here's an array $data:

0 => Array (8)
id => 8
name => test entry3 3 2fsdfsdfs sdf sdf
address => empty
city => empty
state => 66
closingdate => empty
loanamount => 0
date => empty
1 => Array (8)
id => 9
name => test entry 2
address => empty
city => empty
state => 66
closingdate => empty
loanamount => 0
date => empty
2 => Array (8)
id => 10
name => empty
address => empty
city => empty
state => 66
closingdate => empty
loanamount => 0
date => empty

I would like to iterate through this array and add an element to each called
url which will be assigned based on a function of id. In pseudocode:

foreach ($data as $array) {
$array['url'] = SomeCoolFunctio n("$array['id']");
}

How can I do this? Assigning values to elements and working with existing
arrays in Perl is extremely easy. This appears to be a weakness in the
design of PHP. Thoughts?

TIA

GN

[Pedro Graca]

Re: need to assign/edit values in multidimensiona l associative arrays

Golf Nut wrote:
(snip)[color=blue]
> I would like to iterate through this array and add an element to each called
> url which will be assigned based on a function of id. In pseudocode:
>
> foreach ($data as $array) {
> $array['url'] = SomeCoolFunctio n("$array['id']");
> }
>
> How can I do this? Assigning values to elements and working with existing
> arrays in Perl is extremely easy. This appears to be a weakness in the
> design of PHP. Thoughts?[/color]

Try

foreach ($data as $k=>$array) {
$data[$k]['url'] = SomeCoolFunctio n($array['id']);
}



Or, if you don't like it (I don't), use the array_walk() function

http://www.php.net/array_walk

function AnotherCoolFunc tion(&$element, $key) {
$element['url'] = SomeCoolFunctio n($element['id']);
}
array_walk($dat a, 'AnotherCoolFun ction');


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[Andy Hassall]

Re: need to assign/edit values in multidimensiona l associative arrays

On Thu, 27 May 2004 19:55:49 GMT, "Golf Nut"
<trippsathyperc oncom-golfnut@yahoo.c om> wrote:
[color=blue]
>I am finding that altering and affecting values in elements in
>multidimension al arrays is a huge pain in the ass. I cannot seem to find a
>consistent way to assign values to arrays. Foreach would clearly be the most
>efficient way to do it, but it only works on a copy of the original array
>and not the original (which is counter intuitive in my estimation).[/color]

Fair point there.
[color=blue]
>For example, here's an array $data:
>
>0 => Array (8)
> id => 8[/color]
[snip]
[color=blue]
>I would like to iterate through this array and add an element to each called
>url which will be assigned based on a function of id. In pseudocode:
>
>foreach ($data as $array) {
> $array['url'] = SomeCoolFunctio n("$array['id']");
>}
>
>How can I do this? Assigning values to elements and working with existing
>arrays in Perl is extremely easy. This appears to be a weakness in the
>design of PHP. Thoughts?[/color]

Depends how you look at it - possibly it's more that Perl has some outstanding
syntax in this area; processing data structures can be done very concisely with
things like map and hash slices that don't have equivalents in many other
languages.

Since you can't get a reference to the original array element out of a plain
PHP foreach loop, one idiom is to get the key and reference the array again in
the loop.

foreach ($data as $key => $array) {
$data[$key]['url'] = SomeCoolFunctio n($array['id']);
}

If you still want something Perl-ish there's always array_map or array_walk
but anonymous sub syntax in PHP isn't as neat as Perl either. Something like:

array_walk($dat a,
create_function ('&$a', '$a["url"] = SomeCoolFunctio n($a["id"]);'));

Yuk :-(

--
Andy Hassall <andy@andyh.co. uk> / Space: disk usage analysis tool
http://www.andyh.co.uk / http://www.andyhsoftware.co.uk/space

[Golf Nut]

Re: need to assign/edit values in multidimensiona l associative arrays

Thanks so much both of you who responded - I could have sworn that I tried
this particular idiom, but apparently not!

A thought for php is perhaps to modify it so that if you're performing an
assignment on an array within a foreach construct (or any construct, for
that matter), that it performs it on the original. I don't know if this
would add any overhead to the code; the compiler would only do this in case
of assignments, so normal foreach use and other iterations wouldn't impact
performance at all. Thoughts?

Thanks again!

GN

"Pedro Graca" <hexkid@hotpop. com> wrote in message
news:2hn0caFeqr brU1@uni-berlin.de...[color=blue]
> Golf Nut wrote:
> (snip)[color=green]
> > I would like to iterate through this array and add an element to each[/color][/color]
called[color=blue][color=green]
> > url which will be assigned based on a function of id. In pseudocode:
> >
> > foreach ($data as $array) {
> > $array['url'] = SomeCoolFunctio n("$array['id']");
> > }
> >
> > How can I do this? Assigning values to elements and working with[/color][/color]
existing[color=blue][color=green]
> > arrays in Perl is extremely easy. This appears to be a weakness in the
> > design of PHP. Thoughts?[/color]
>
> Try
>
> foreach ($data as $k=>$array) {
> $data[$k]['url'] = SomeCoolFunctio n($array['id']);
> }
>
>
>
> Or, if you don't like it (I don't), use the array_walk() function
> http://www.php.net/array_walk
>
>
> function AnotherCoolFunc tion(&$element, $key) {
> $element['url'] = SomeCoolFunctio n($element['id']);
> }
> array_walk($dat a, 'AnotherCoolFun ction');
>
>
> --
> USENET would be a better place if everybody read: : mail address :
> http://www.catb.org/~esr/faqs/smart-questions.html : is valid for :
> http://www.netmeister.org/news/learn2quote2.html : "text/plain" :
> http://www.expita.com/nomime.html : to 10K bytes :[/color]

[Andy Hassall]

Re: need to assign/edit values in multidimensiona l associative arrays

On Thu, 27 May 2004 21:09:04 GMT, "Golf Nut"
<trippsathyperc oncom-golfnut@yahoo.c om> wrote:
[color=blue]
>A thought for php is perhaps to modify it so that if you're performing an
>assignment on an array within a foreach construct (or any construct, for
>that matter), that it performs it on the original. I don't know if this
>would add any overhead to the code; the compiler would only do this in case
>of assignments, so normal foreach use and other iterations wouldn't impact
>performance at all. Thoughts?[/color]

Or perhaps as:

foreach ($array as $value) // work on a copy

foreach ($array as &$value) // reference to the actual value

Avoids breaking backwards compatibility that way.

--
Andy Hassall <andy@andyh.co. uk> / Space: disk usage analysis tool
http://www.andyh.co.uk / http://www.andyhsoftware.co.uk/space

[Philipp Kern]

Re: need to assign/edit values in multidimensiona l associative arrays

On 2004-05-27, Andy Hassall <andy@andyh.co. uk> wrote:[color=blue]
> foreach ($array as &$value) // reference to the actual value[/color]

I would be in favour of this one. But adding the key to the foreach construct
and refer to the original array by the key isn't that hard either, it's just
a bit uncommon.
AFAIK in PHP5 all variables are references, so I hope this will be automagically
implemented there and the comments at php.net for `foreach' seem to prove this.

Bye,
phil
--
Please send replys (not followups) to the address set in Reply-To.
Philipp Kern - PK2186-RIPE - http://www.philkern.de