removing an item from an array

2012/8/20 Andrew Faulds ajf@ajf.me:

2012/8/20 Andrew Faulds ajf@ajf.me:

2012/8/20 Etienne Kneuss colder@php.net:

On Sun, Aug 19, 2012 at 11:57 PM, Yasuo Ohgaki yohgaki@ohgaki.net
wrote:

2012/8/18 Rasmus Lerdorf rasmus@lerdorf.com:

if(($key = array_search($del_val, $messages)) !== false) {
unset($messages[$key]);
}

Nothing horrible here.

I disagree - this is (or should be) a simple, atomic operation...
yet, you've got a function-call, an intermediary variable, a boolean
test,
and an unset statement repeating the name of the array you're
deleting
from.

This should be a simple statement or function/method-call, and in
most
other languages it would be...

Really? I can't think of a single language that has a call to remove
an
element by value in a key-value hash. Do you have some examples? What
do
you do with duplicates?

Ruby can do (using irb)

ruby-1.9.2-p180 :007 > h = {"apple"=>150, "banana"=>300, "lemon"=>300}
=> {"apple"=>150, "banana"=>300, "lemon"=>300}
ruby-1.9.2-p180 :008 > h.delete_if { |k,v| v==300 }
=> {"apple"=>150}

May be we should have something like

array_delete_if($array, function($v, $k=null) { if ($v == 300) return
true; })

So array_filter?

I'll use it or like for deleting, but the point of this thread is
"intuitive function for deleting element(s)"

array_delete($array, $value|callable)

would be nicer for users, perhaps.

A callable? Wouldn't that mean you couldn't delete strings? :(

If you read my previous post, you'll see why it would be nicer with
callable.

Being unable to remove callables from an array would be very strange, and I
think for the use case you presented array_filter works fine.

Of course it works.

$array = array_filter($array, function($v) use ($del_val) {
return ($v !== $del_val);
});

It does not delete element(s), but creates new array.

void array_delete ( array &$input [, callable $callback = "" |
$values_to_be_deleted ] )

This will delete element(s).
We can use array_walk() to delete element(s) from array also.

php > $array = array(1,2,3,4,5);
php > array_walk($array, function($val, $key) use (&$array) {if ($val
== 3) unset($array[$key]);});
php > var_dump($array);
array(4) {
[0]=>
int(1)
[1]=>
int(2)
[3]=>
int(4)
[4]=>
int(5)
}

I suppose this isn't an intuitive way for novices because stack
overflow's answers
didn't have this method that actually delete element(s) from an array.

Adding an intuitive element deletion function is the point of this
thread, isn't it?
I'll vote +1 for adding array_delete().

Regards,

--
Yasuo Ohgaki

Ruby can do (using irb)

ruby-1.9.2-p180 :007 > h = {"apple"=>150, "banana"=>300, "lemon"=>300}
=> {"apple"=>150, "banana"=>300, "lemon"=>300}
ruby-1.9.2-p180 :008 > h.delete_if { |k,v| v==300 }
=> {"apple"=>150}

May be we should have something like

array_delete_if($array, function($v, $k=null) { if ($v == 300) return
true; })

--
Yasuo Ohgaki

--
Andrew Faulds
http://ajf.me/

Adding array_delete would allow you to use it like a set more
It's not a set and wasn't meant to be. If you want really bad set
behavior, feel free to use an array as one.
Arrays also aren't lists or associative arrays, strictly speaking.

And there is another use case: removing of list items by value, instead
of key.

--
Andrew Faulds
http://ajf.me/

You are basically asking to alias array_filter with "array_delete". That is
a very slippery slope. I think array_filter is a very obvious choice
to remove something from an array. The "filter" function/method is common
in functional languages (and functional frameworks like Underscore).
This about sums up my opinion on deleting things by value on a PHP array.
** Me and Levi had a private email back-and-forth about this. Like many
things here, this discussion has become a pseudo-argument, and it's
unclear whether people actually think it's a good idea or not. So let's
make an RFC (I think array_delete($array, $value, $all=false), mirrors
Python's replace-one-only by default), vote on it, and that can decide
things. So we can avoid argument. Don't like the syntax? Vote against
it, but I don't see how it could be much better.

--
Andrew Faulds
http://ajf.me/

Some major points to consider for array_delete's behavior:

1. Should items be compared with ==, ===, or custom comparison? If
   we use == or === we'd probably add array_udelete to allow a
   custom comparator.
2. Should it stop when it encounters the first value that matches? If
   it does, should we add a function that searches in the reverse
   direction?
3. Should it modify the array in-place? If so, should we have another
   function that returns a copy of the array that does not include the
   removed value(s) instead?

If someone wants to go through and define all of these cases and
propose a patch, more power to them.

Here are some reasons that aren't related to the above as to why I'm
against adding array_delete:

1. PHP arrays are not sets. PHP arrays are meant to be a list and an
   associative array. As such, a PHP array can act as any* data structure
   that can be built from a list or associative array. A data structure
   that removes something by value is typically associated with a set and
   therefore does not belong in an array.
2. Using other array functions cover this use case AND do a better
   job. Want to remove the first instance of the value? Use
   array_search to find the index and unset it. If you want to reorder
   the array you can use array_search to find the index and use
   array_slice. Want to remove all instances of the value in the
   array? Use array_filter.

Am 20.08.2012 19:00, schrieb Andrew Faulds:

May be we should have something like

array_delete_if($array, function($v, $k=null) { if ($v == 300)
return
true; })
So array_filter?
I'll use it or like for deleting, but the point of this thread is
"intuitive function for deleting element(s)"

array_delete($array, $value|callable)

would be nicer for users, perhaps.

You are basically asking to alias array_filter with "array_delete".
That is
a very slippery slope. I think array_filter is very a very obvious
choice
to remove something from an array. The "filter" function/method is
common
in functional languages (and functional frameworks like Underscore).

These are things developers just need to learn as part of development.
Really, this is entire thread should be on stack overflow, not
internals.

You seem a little arrogant. Arguably, a lot of array functions are
unnecessary. But PHP is not supposed to be an extremely minimal
language. Convenience functions are a good thing.

We have array_pad for instance: completely unnecessary, you can do it
manually with other array functions. Array_fill_keys and array_fill,
too. array_flip is also unnecessary. Heck, who needs sorting, you can do
that manually too.

array_delete would be a more convenient, and more readable way to remove
a value from an array. Yes, you can already remove array items, that's
not the point. The point is this way is simpler and more convenient.

So you just want a convenient and readable way and you realise
yourself, that it is really simple to implement. So: Why don't you
just implement it yourself?

function array_delete($array, $value) {
// Your code here
}

What I don't understand is, why should every function goes directly
into the core, if you can achieve exactly the same without core changes?

I'd rather not argue any further about this (let's make an RFC and
vote). I've already addressed this point.

Regards,
Sebastian

Also, as someone else mentioned, PHP's universal collection datatype is
a great thing. It is an associative array, it is a list, it is a tuple,
it is a set, it can be used in many ways, it's incredibly versatile.
Adding array_delete would allow you to use it like a set more easily.

Just my 2½¢ :)

--
Andrew Faulds
http://ajf.me/

I have a login (mindplay) but I do not have permission to post or edit
anything on the wiki...

Please let this die until someone is serious enough to come up with an
rfc. This has been nothing but counterproductive arguing. If someone feels
strongly about it, write an rfc then we can discuss?

Hi,

2012/8/21 Herman Radtke hermanradtke@gmail.com:

May be we should have something like

array_delete_if($array, function($v, $k=null) { if ($v == 300)
return
true; })

So array_filter?

I'll use it or like for deleting, but the point of this thread is
"intuitive function for deleting element(s)"

array_delete($array, $value|callable)

would be nicer for users, perhaps.

You are basically asking to alias array_filter with "array_delete".
That is
a very slippery slope. I think array_filter is very a very obvious
choice to
remove something from an array. The "filter" function/method is common
in
functional languages (and functional frameworks like Underscore).

These are things developers just need to learn as part of development.
Really, this is entire thread should be on stack overflow, not
internals.

I guess you haven't read later post.

You've also made a novice mistake.
array_filter() DO NOT delete elements, but creates new array.
array_delete() is another form of array_walk(), not array_filter().
See my posts.

Having a API for dedicated task is good thing.
Who would argue array_pop()/array_push() isn't needed?

Regards,

--
Yasuo Ohgaki
yohgaki@ohgaki.net