Help needed to build an array

[Sims]

Hi

I have a table with something like

ID PARENT

0 | -1
1 | -1
2 | 1
3 | 1
4 | 2
5 | -1
6 | 4

And i want to build an array so i can output the data in the form

0
1
|--2
|----4
| |----5
|--3
5

Where 2 is a child of 1, and 4 is a child of 2 and so on.
I could create an array like $data[$id][$parent] but how would i output the
data where i get all the children of, say, ID=1 and all the children of ID =
4.
What would be the best way to achieve the above using MySQL db and php?

If i read all the data sorted by PARENT i might be able to read the whole
table at once and add all the data to one array?

Any ideas?

Regards.
Simon/

[John Smith]

Re: Help needed to build an array

Children and Parents aren't used in Arrays, are you using Objects or
Arrays???

"Sims" <siminfrance@ho tmail.com> schreef in bericht
news:c1vnh8$1ne iht$1@ID-162430.news.uni-berlin.de...[color=blue]
> Hi
>
> I have a table with something like
>
> ID PARENT
>
> 0 | -1
> 1 | -1
> 2 | 1
> 3 | 1
> 4 | 2
> 5 | -1
> 6 | 4
>
> And i want to build an array so i can output the data in the form
>
> 0
> 1
> |--2
> |----4
> | |----5
> |--3
> 5
>
> Where 2 is a child of 1, and 4 is a child of 2 and so on.
> I could create an array like $data[$id][$parent] but how would i output[/color]
the[color=blue]
> data where i get all the children of, say, ID=1 and all the children of ID[/color]
=[color=blue]
> 4.
> What would be the best way to achieve the above using MySQL db and php?
>
> If i read all the data sorted by PARENT i might be able to read the whole
> table at once and add all the data to one array?
>
> Any ideas?
>
> Regards.
> Simon/
>
>[/color]

[Sims]

Re: Help needed to build an array

Hi,

"John Smith" <someone@nobody .com> wrote in message
news:c1vq20$ro9 $1@news3.tilbu1 .nb.home.nl...[color=blue]
> Children and Parents aren't used in Arrays, are you using Objects or
> Arrays???
>[/color]

I am not using anything yet, i just want to know what would be the best way
to read the data
so that i can get the children(s) of all ids.

It could be a class i guess, I want a function that would read the data from
the database and build all the parents recursively so that i could, for
example, get all the children for ID = 1 and i would return 2, 3.

I want to build the array/class in one call of the database and not all
every time i need to find the child of an ID.
[color=blue][color=green]
> > ID PARENT
> >
> > 0 | -1
> > 1 | -1
> > 2 | 1
> > 3 | 1
> > 4 | 2
> > 5 | -1
> > 6 | 4
> >
> > And i want to build an array so i can output the data in the form
> >
> > 0
> > 1
> > |--2
> > |----4
> > | |----5
> > |--3
> > 5
> >
> > Where 2 is a child of 1, and 4 is a child of 2 and so on.
> > I could create an array like $data[$id][$parent] but how would i output[/color]
> the[color=green]
> > data where i get all the children of, say, ID=1 and all the children of[/color][/color]
ID[color=blue]
> =[color=green]
> > 4.
> > What would be the best way to achieve the above using MySQL db and php?
> >
> > If i read all the data sorted by PARENT i might be able to read the[/color][/color]
whole[color=blue][color=green]
> > table at once and add all the data to one array?
> >
> > Any ideas?
> >
> > Regards.
> > Simon/
> >
> >[/color]
>
>[/color]

[col]

Re: Help needed to build an array


"John Smith" <someone@nobody .com> wrote in message
news:c1vq20$ro9 $1@news3.tilbu1 .nb.home.nl...[color=blue]
> Children and Parents aren't used in Arrays, are you using Objects or
> Arrays???
>
> "Sims" <siminfrance@ho tmail.com> schreef in bericht
> news:c1vnh8$1ne iht$1@ID-162430.news.uni-berlin.de...[color=green]
> > Hi
> >
> > I have a table with something like
> >
> > ID PARENT
> >
> > 0 | -1
> > 1 | -1
> > 2 | 1
> > 3 | 1
> > 4 | 2
> > 5 | -1
> > 6 | 4
> >
> > And i want to build an array so i can output the data in the form
> >
> > 0
> > 1
> > |--2
> > |----4
> > | |----5
> > |--3
> > 5
> >
> > Where 2 is a child of 1, and 4 is a child of 2 and so on.
> > I could create an array like $data[$id][$parent] but how would i output[/color]
> the[color=green]
> > data where i get all the children of, say, ID=1 and all the children of[/color][/color]
ID[color=blue]
> =[color=green]
> > 4.
> > What would be the best way to achieve the above using MySQL db and php?
> >
> > If i read all the data sorted by PARENT i might be able to read the[/color][/color]
whole[color=blue][color=green]
> > table at once and add all the data to one array?
> >
> > Any ideas?
> >
> > Regards.
> > Simon/
> >[/color][/color]
think he wants arrays inside arrays... to output.. something like this would
work

foreach($data['array of some sort'] as $key => $value)

{

if(is_array($va lue))

{

foreach($value as $key1 => $value1)

{

if(is_array($va lue1))

{

foreach($value1 as $key2 => $value2)

{

do something with $value2

}

}

else { do something with $value1}

}

}

else {do something with $value}

}

not the best way of doing thing but that should get you 3 deep, sure ya see
whats happening

[Sims]

Re: Help needed to build an array

Hi,

[color=blue]
> think he wants arrays inside arrays... to output.. something like this[/color]
would[color=blue]
> work
>[/color]

<snip code>
[color=blue]
>
> not the best way of doing thing but that should get you 3 deep, sure ya[/color]
see[color=blue]
> whats happening
>[/color]

Thanks but i do not know how deep it goes, maybe that is what i should use a
class.
Where class definition is something like

class ITEMS
{
var $iParent = // int id of parent or -1 if no parent
var $aChildren = // array of class ITEMS or false if no children

// and some functions like
function GetChild( $id )
{
// return the array all the children
}
}

Or something like that.
But i would i build the class.

Simon.

[Shawn Wilson]

Re: Help needed to build an array

Sims wrote:[color=blue]
>
> Hi
>
> I have a table with something like
>
> ID PARENT
>
> 0 | -1
> 1 | -1
> 2 | 1
> 3 | 1
> 4 | 2
> 5 | -1
> 6 | 4
>
> And i want to build an array so i can output the data in the form
>
> 0
> 1
> |--2
> |----4
> | |----5
> |--3
> 5
>
> Where 2 is a child of 1, and 4 is a child of 2 and so on.
> I could create an array like $data[$id][$parent] but how would i output the
> data where i get all the children of, say, ID=1 and all the children of ID =
> 4.
> What would be the best way to achieve the above using MySQL db and php?
>
> If i read all the data sorted by PARENT i might be able to read the whole
> table at once and add all the data to one array?[/color]

Try a recursive function and 2 arrays, passed by reference.
Arrays: oldarray()(cont aining table results) and newarray() (empty)

function makelist(& $oldarray,& $newarray, $id) {
//go through old array, searching for anything with parent $id
//if found, add to new array in correct place, delete from old array and call
makelist with new id
}

Start your function off with $id=-1.
The actual code is a bit trickier than the comments.
Consider what happens if:
-parent doesn't exist
-there are >1 children - how do you suborder them?
-there's a loop (id=>1, parent=>2)(id=> 2,parent=>1) //should never happen

Anyway, that should order your stuff.
For echoing the results, you could write a function getindent($id)

function getindent($id, $newarray) {
$indent=0;
$foundit=0;

foreach($newarr ay as $foo){
if ($foo['id'] == $id) {
$parent=$foo['parent'];
if ($parent == -1)
return $indent;
break;
}
}

while ($foundit==0) {
foreach($newarr ay as $foo){
if ($parent == $foo['id']) {
$indent++;
if ($foo['parent'] == -1)
return $indent;
$parent = $foo['parent'];
break;
}
}
}
}

This function is untested and likely contains typos and/or small logic errors.
It does not have any failsafes (if an array element has the id of a non-existant
parent or if there's a loop in the parents, as above, it will loop until the
script times out). If you use it, I suggest you improve it.

Then to display:

foreach($newarr ay as $foo) {
$indents = getindent(-1, $newarray);
for($i=0;$i<$in dents;++$i)
echo '-';
echo $foo['id']."<br>";
}

Regards,
Shawn
--
Shawn Wilson
shawn@glassgian t.com

http://www.glassgiant.com

[Erik Johnson]

Re: Help needed to build an array

I would strongly disagree with Mr. Smith's broad assertion that children
and parents aren't used in arrays. Arrays are a tool to serve their master.
If I am understanding the goal here, you want to map a parent id to an array
of children id's. Array elements can themselves be arrays, so this is no big
deal. You call the database, say with something like "select * from parent",
and you get back all the rows in your table.

You then iterate through each row in the table, building up your data
structure (I'm assuming -1 is being used here to represent no parent).

#set $n_rows to the number of rows in your table
for ($i = 0; $i < $n_rows; $i++)
{
# get your parent id poked into $pid, child id poked into $cid
if ($pid != -1)
$data[$pid][] = $cid;
}

$data then is built as a 2-D array and comes out looking like:
$data[1] = array(2, 3);
$data[2] = array(4);
$data[4] = array(6);

The formatted output you show below doesn't make any sense to me, so
I'll leave that part to you, but given a parent id, $data maps to an array
of children ID - that is the crux of your issue as I understand it.

Just FYI, this looks like a relatively expensive thing to do - I don't
know anything about caching data from one page invocation to the next, but
unless you have some sort of a caching mechanism you are (potentially)
downloading this whole table and building your mapping on every page
request. Maybe this is in a standalone script so it doesn't matter, or maybe
you don't care about performance anyway - but just something to consider.

HTH,
-ej


"Sims" <siminfrance@ho tmail.com> wrote in message
news:c1vqsh$1mo l76$1@ID-162430.news.uni-berlin.de...[color=blue]
> Hi,
>
> "John Smith" <someone@nobody .com> wrote in message
> news:c1vq20$ro9 $1@news3.tilbu1 .nb.home.nl...[color=green]
> > Children and Parents aren't used in Arrays, are you using Objects or
> > Arrays???
> >[/color]
>
> I am not using anything yet, i just want to know what would be the best[/color]
way[color=blue]
> to read the data
> so that i can get the children(s) of all ids.
>
> It could be a class i guess, I want a function that would read the data[/color]
from[color=blue]
> the database and build all the parents recursively so that i could, for
> example, get all the children for ID = 1 and i would return 2, 3.
>
> I want to build the array/class in one call of the database and not all
> every time i need to find the child of an ID.
>[color=green][color=darkred]
> > > ID PARENT
> > >
> > > 0 | -1
> > > 1 | -1
> > > 2 | 1
> > > 3 | 1
> > > 4 | 2
> > > 5 | -1
> > > 6 | 4
> > >
> > > And i want to build an array so i can output the data in the form
> > >
> > > 0
> > > 1
> > > |--2
> > > |----4
> > > | |----5
> > > |--3
> > > 5
> > >
> > > Where 2 is a child of 1, and 4 is a child of 2 and so on.
> > > I could create an array like $data[$id][$parent] but how would i[/color][/color][/color]
output[color=blue][color=green]
> > the[color=darkred]
> > > data where i get all the children of, say, ID=1 and all the children[/color][/color][/color]
of[color=blue]
> ID[color=green]
> > =[color=darkred]
> > > 4.
> > > What would be the best way to achieve the above using MySQL db and[/color][/color][/color]
php?[color=blue][color=green][color=darkred]
> > >
> > > If i read all the data sorted by PARENT i might be able to read the[/color][/color]
> whole[color=green][color=darkred]
> > > table at once and add all the data to one array?
> > >
> > > Any ideas?
> > >
> > > Regards.
> > > Simon/
> > >
> > >[/color]
> >
> >[/color]
>
>[/color]

[Sims]

Re: Help needed to build an array

[color=blue]
> I would strongly disagree with Mr. Smith's broad assertion that[/color]
children[color=blue]
> and parents aren't used in arrays. Arrays are a tool to serve their[/color]
master.[color=blue]
> If I am understanding the goal here, you want to map a parent id to an[/color]
array[color=blue]
> of children id's. Array elements can themselves be arrays, so this is no[/color]
big[color=blue]
> deal. You call the database, say with something like "select * from[/color]
parent",[color=blue]
> and you get back all the rows in your table.[/color]

i tend to agree with you. Arrays might be the right thing for me.
But an object might also do the trick, i think.
[color=blue]
>
> You then iterate through each row in the table, building up your data
> structure (I'm assuming -1 is being used here to represent no parent).
>[/color]

<snip code >

All i want is to call the database, "select * from table1"
and then build some form of array/object that will contain
1) It's own ID number
2) The number of it's father, (-1 been no father).

So looking at it like that i could create a class

class DATA_1{
$father;
$number;
}

class DATA_2{
$data_1 = array(); // of class data_1
}

fill the array using a select.

but then how would i output it?
maybe somerecuring function...like

// $data_2 is class DATA_2
function print_tree( $depth, $id )
{
// output the $id using the depth
$data = $data_2->GetChildren( -1 ); would return all the item whose
parent is -1;
foreach( $data as $x ){
print_tree( ($depth+1), $x );
}
}

So the output would print all the father followed by all the children's...

i would start the loop with
print_tree( 0, -1 )

I think...
And that way i would only call the DB once to build the array.
[color=blue]
>
> The formatted output you show below doesn't make any sense to me, so
> I'll leave that part to you, but given a parent id, $data maps to an array
> of children ID - that is the crux of your issue as I understand it.[/color]

The formatted thing was just to try to explain what i was after.

[color=blue]
>
> Just FYI, this looks like a relatively expensive thing to do - I don't
> know anything about caching data from one page invocation to the next, but
> unless you have some sort of a caching mechanism you are (potentially)
> downloading this whole table and building your mapping on every page
> request. Maybe this is in a standalone script so it doesn't matter, or[/color]
maybe[color=blue]
> you don't care about performance anyway - but just something to consider.[/color]

Yes you are right but it is only used in one page, (for the administrator to
check that the data are still in good order).
And secondly it is only a 10/20 items table max.

But i am always looking for better ways to do things, if you know of a
better way...

Simon.

[Erik Johnson]

Re: Help needed to build an array


"Sims" <siminfrance@ho tmail.com> wrote in message
news:c207vb$1nh 8on$1@ID-162430.news.uni-berlin.de...
[color=blue]
> All i want is to call the database, "select * from table1"
> and then build some form of array/object that will contain
> 1) It's own ID number
> 2) The number of it's father, (-1 been no father).[/color]

This is a *different* (but still trivial) problem. Here's an array
based solution:

#set $n_rows to the number of rows in your table
for ($i = 0; $i < $n_rows; $i++)
{
# get your parent id poked into $pid, child id poked into $cid
$data[$cid] = $pid;
}


The second part, the question that you are hinting at but haven't asked
directly is

"How do I pretty print a textual representation of a general tree?"

That's a very non-trivial problem. In fact, there is nothing here that
even implies a true tree (i.e., there is nothing preventing you from
creating loops in your parent-child table). In the general case, each node
can (recursively) have any number of children. So, I don't have an easy
answer for how you are going to pretty-print that. That doesn't mean it's
impossible to do, just that it's very non-trivial. If you just need to see
the information, go back to my first solution, and recursively iterate
through the keys and print lines like:

parent0: {}
parent1: {child2, child3}
parent2: {child4}
parent3: {}
parent4: {child6}
parent5: {}
parent6: {}

Or use the solution in this post, and print lines like:

child0: NO-parent
child1: NO-parent
child2: parent1
....

For a given node, you will have to trace the lineage through several
lines. But this is essentially just dumping your table.

If you are serious about solving the harder problem, pretty-printing a
general tree, first come up with a textual representation that addresses the
general case. It's silly to waste time taking pot-shots in the dark at code
fragments that sorta-might-maybe-kinda help with a piece of the problem
without first understanding the ultimate goal.

-ej

[John Smith]

Re: Help needed to build an array


"Erik Johnson" <ej@just.post.h ere.com> schreef in bericht
news:4044cf1b$1 @news.zianet.co m...[color=blue]
>
> "Sims" <siminfrance@ho tmail.com> wrote in message
> news:c207vb$1nh 8on$1@ID-162430.news.uni-berlin.de...
>[color=green]
> > All i want is to call the database, "select * from table1"
> > and then build some form of array/object that will contain
> > 1) It's own ID number
> > 2) The number of it's father, (-1 been no father).[/color]
>
> This is a *different* (but still trivial) problem. Here's an array
> based solution:
>
> #set $n_rows to the number of rows in your table
> for ($i = 0; $i < $n_rows; $i++)
> {
> # get your parent id poked into $pid, child id poked into $cid
> $data[$cid] = $pid;
> }
>
>
> The second part, the question that you are hinting at but haven't[/color]
asked[color=blue]
> directly is
>
> "How do I pretty print a textual representation of a general tree?"
>
> That's a very non-trivial problem. In fact, there is nothing here that
> even implies a true tree (i.e., there is nothing preventing you from
> creating loops in your parent-child table). In the general case, each node
> can (recursively) have any number of children. So, I don't have an easy
> answer for how you are going to pretty-print that. That doesn't mean it's
> impossible to do, just that it's very non-trivial. If you just need to see
> the information, go back to my first solution, and recursively iterate
> through the keys and print lines like:
>
> parent0: {}
> parent1: {child2, child3}
> parent2: {child4}
> parent3: {}
> parent4: {child6}
> parent5: {}
> parent6: {}
>
> Or use the solution in this post, and print lines like:
>
> child0: NO-parent
> child1: NO-parent
> child2: parent1
> ...
>
> For a given node, you will have to trace the lineage through several
> lines. But this is essentially just dumping your table.
>
> If you are serious about solving the harder problem, pretty-printing a
> general tree, first come up with a textual representation that addresses[/color]
the[color=blue]
> general case. It's silly to waste time taking pot-shots in the dark at[/color]
code[color=blue]
> fragments that sorta-might-maybe-kinda help with a piece of the problem
> without first understanding the ultimate goal.
>
> -ej
>
>[/color]
Beware if you're using a loop to print trees, you might get an infinite
(recursive) loop.
e.g.
1 points to 2
2 points to 4
4 points to 3
3 points to 1

Nice to mention is print_r()
It had the same problem, although it's solved now, try print_r($_GLOBA LS);

[John Smith]

Re: Help needed to build an array


"Sims" <siminfrance@ho tmail.com> schreef in bericht
news:c1vrq6$1mv 0j7$1@ID-162430.news.uni-berlin.de...[color=blue]
> Hi,
>
>[color=green]
> > think he wants arrays inside arrays... to output.. something like this[/color]
> would[color=green]
> > work
> >[/color]
>
> <snip code>
>[color=green]
> >
> > not the best way of doing thing but that should get you 3 deep, sure ya[/color]
> see[color=green]
> > whats happening
> >[/color]
>
> Thanks but i do not know how deep it goes, maybe that is what i should use[/color]
a[color=blue]
> class.
> Where class definition is something like
>
> class ITEMS
> {
> var $iParent = // int id of parent or -1 if no parent
> var $aChildren = // array of class ITEMS or false if no[/color]
children[color=blue]
>
> // and some functions like
> function GetChild( $id )
> {
> // return the array all the children
> }
> }
>
> Or something like that.
> But i would i build the class.
>
> Simon.
>
>[/color]
Maybe this will help
WARNING untested script so beware of typos and other bad stuff.

$prefix='';
$maintree=array ();

print_tree($mai ntree,$prefix)

function print_tree($tre e,$prefix)
{
if(is_array($tr ee))
{
foreach($tree as $newtree)
{
print_tree($new tree,$prefix.'---');
}
}
else echo $prefix.$tree." <br />\r\n";
}