Retrieving array values by range of keys

[WildernessCat]

Hello there!

Suppose I have an associative array that looks like this:
$arr['alpha_1'] = 'some value';
$arr['alpha_3'] = 'some value';
$arr['alpha_4'] = 'some value';
$arr['beta_2'] = 'some value';
$arr['beta_4'] = 'some value';
$arr['beta_6'] = 'some value';
$arr['gamma_1'] = 'some value';
$arr['gamma_5'] = 'some value';
$arr['gamma_6'] = 'some value';
$arr['gamma_7'] = 'some value';

Let's assume that the array is reasonably large (hundreds of entries).

Is there an efficient way of getting all the items whose key starts
with 'beta'? (without doing a foreach/strncmp loop?)

Thanks in advance,
Danny

[Captain Paralytic]

On 15 Oct, 14:09, WildernessCat <[e-mail]:

Hello there!

Suppose I have an associative array that looks like this:
$arr['alpha_1'] = 'some value';
$arr['alpha_3'] = 'some value';
$arr['alpha_4'] = 'some value';
$arr['beta_2'] = 'some value';
$arr['beta_4'] = 'some value';
$arr['beta_6'] = 'some value';
$arr['gamma_1'] = 'some value';
$arr['gamma_5'] = 'some value';
$arr['gamma_6'] = 'some value';
$arr['gamma_7'] = 'some value';

Let's assume that the array is reasonably large (hundreds of entries).

Is there an efficient way of getting all the items whose key starts
with 'beta'? (without doing a foreach/strncmp loop?)

Thanks in advance,
Danny

Something like:

preg_grep('/^beta/',array_keys($arr));

should give you all the keys that start with 'beta'

[Sanders Kaufman]

"Captain Paralytic" <pa**********@yahoo.comwrote in message
news:11*********************@i13g2000prf.googlegro ups.com...

On 15 Oct, 14:09, WildernessCat <[e-mail]:

>Hello there!

Suppose I have an associative array that looks like this:
$arr['alpha_1'] = 'some value';
$arr['alpha_3'] = 'some value';
$arr['alpha_4'] = 'some value';
$arr['beta_2'] = 'some value';
$arr['beta_4'] = 'some value';
$arr['beta_6'] = 'some value';
$arr['gamma_1'] = 'some value';
$arr['gamma_5'] = 'some value';
$arr['gamma_6'] = 'some value';
$arr['gamma_7'] = 'some value';

Let's assume that the array is reasonably large (hundreds of entries).

Is there an efficient way of getting all the items whose key starts
with 'beta'? (without doing a foreach/strncmp loop?)

Thanks in advance,
Danny

Something like:

preg_grep('/^beta/',array_keys($arr));

should give you all the keys that start with 'beta'

What does the return value look like - array? string?

[WildernessCat]

On Oct 15, 3:17 pm, Captain Paralytic <[e-mail]:

On 15 Oct, 14:09, WildernessCat <[e-mail]:

Hello there!

Suppose I have an associative array that looks like this:
$arr['alpha_1'] = 'some value';
$arr['alpha_3'] = 'some value';
$arr['alpha_4'] = 'some value';
$arr['beta_2'] = 'some value';
$arr['beta_4'] = 'some value';
$arr['beta_6'] = 'some value';
$arr['gamma_1'] = 'some value';
$arr['gamma_5'] = 'some value';
$arr['gamma_6'] = 'some value';
$arr['gamma_7'] = 'some value';

Let's assume that the array is reasonably large (hundreds of entries).

Is there an efficient way of getting all the items whose key starts
with 'beta'? (without doing a foreach/strncmp loop?)

Thanks in advance,
Danny

Something like:

preg_grep('/^beta/',array_keys($arr));

should give you all the keys that start with 'beta'

Yes, it sure looks more compact in the code, but the question is
whether it's more efficient? I have a gut feeling that there is no
efficient way.

By the way I forgot to mention that the array is not sorted.

[Captain Paralytic]

On 15 Oct, 14:37, "Sanders Kaufman" <[e-mail]:

"Captain Paralytic" <[e-mail] in message

news:11*********************@i13g2000prf.googlegro ups.com...

On 15 Oct, 14:09, WildernessCat <[e-mail]:

Hello there!

Suppose I have an associative array that looks like this:
$arr['alpha_1'] = 'some value';
$arr['alpha_3'] = 'some value';
$arr['alpha_4'] = 'some value';
$arr['beta_2'] = 'some value';
$arr['beta_4'] = 'some value';
$arr['beta_6'] = 'some value';
$arr['gamma_1'] = 'some value';
$arr['gamma_5'] = 'some value';
$arr['gamma_6'] = 'some value';
$arr['gamma_7'] = 'some value';

Let's assume that the array is reasonably large (hundreds of entries).

Is there an efficient way of getting all the items whose key starts
with 'beta'? (without doing a foreach/strncmp loop?)

Thanks in advance,
Danny

Something like:

preg_grep('/^beta/',array_keys($arr));

should give you all the keys that start with 'beta'

What does the return value look like - array? string?- Hide quoted text -

- Show quoted text -

Why ask me when you can just go to:
http://uk3.php.net/manual/en/function.preg-grep.php
and read it there?

Note that this won't solve the OP's whole problem as he wants the
values rather than the keys, but it's a start.

[Sanders Kaufman]

"Captain Paralytic" <pa**********@yahoo.comwrote in message
news:11**********************@i38g2000prf.googlegr oups.com...

On 15 Oct, 14:37, "Sanders Kaufman" <[e-mail]:

preg_grep('/^beta/',array_keys($arr));

should give you all the keys that start with 'beta'

What does the return value look like - array? string?- Hide quoted
text -

- Show quoted text -

Why ask me when you can just go to:
http://uk3.php.net/manual/en/function.preg-grep.php
and read it there?

Because, after a bout with meningitis, my brain doesn't work as well as it
used to.
I read one page after another - and have no idea what I read.
But when I discuss - it registers.

[Captain Paralytic]

On 15 Oct, 14:43, WildernessCat <[e-mail]:

On Oct 15, 3:17 pm, Captain Paralytic <[e-mail]:

On 15 Oct, 14:09, WildernessCat <[e-mail]:

Hello there!

Suppose I have an associative array that looks like this:
$arr['alpha_1'] = 'some value';
$arr['alpha_3'] = 'some value';
$arr['alpha_4'] = 'some value';
$arr['beta_2'] = 'some value';
$arr['beta_4'] = 'some value';
$arr['beta_6'] = 'some value';
$arr['gamma_1'] = 'some value';
$arr['gamma_5'] = 'some value';
$arr['gamma_6'] = 'some value';
$arr['gamma_7'] = 'some value';

Let's assume that the array is reasonably large (hundreds of entries).

Is there an efficient way of getting all the items whose key starts
with 'beta'? (without doing a foreach/strncmp loop?)

Thanks in advance,
Danny

Something like:

preg_grep('/^beta/',array_keys($arr));

should give you all the keys that start with 'beta'

Yes, it sure looks more compact in the code, but the question is
whether it's more efficient? I have a gut feeling that there is no
efficient way.

By the way I forgot to mention that the array is not sorted.- Hide quoted text -

- Show quoted text -

The fact that it is not sorted shouldn't matter. As far as efficiency
goes, it is all handled by a BIF as opposed to interpreted code, so it
has the opportunity to be more efficient.

Now, I don't know how you want to use the results but this leaves you
with an array containing all the keys that you need for later use.

[WildernessCat]

On Oct 15, 5:05 pm, Captain Paralytic <[e-mail]:

On 15 Oct, 14:43, WildernessCat <[e-mail]:

On Oct 15, 3:17 pm, Captain Paralytic <[e-mail]:

On 15 Oct, 14:09, WildernessCat <[e-mail]:

Hello there!

Suppose I have an associative array that looks like this:
$arr['alpha_1'] = 'some value';
$arr['alpha_3'] = 'some value';
$arr['alpha_4'] = 'some value';
$arr['beta_2'] = 'some value';
$arr['beta_4'] = 'some value';
$arr['beta_6'] = 'some value';
$arr['gamma_1'] = 'some value';
$arr['gamma_5'] = 'some value';
$arr['gamma_6'] = 'some value';
$arr['gamma_7'] = 'some value';

Let's assume that the array is reasonably large (hundreds of entries).

Is there an efficient way of getting all the items whose key starts
with 'beta'? (without doing a foreach/strncmp loop?)

Thanks in advance,
Danny

Something like:

preg_grep('/^beta/',array_keys($arr));

should give you all the keys that start with 'beta'

Yes, it sure looks more compact in the code, but the question is
whether it's more efficient? I have a gut feeling that there is no
efficient way.

By the way I forgot to mention that the array is not sorted.- Hide quoted text -

- Show quoted text -

The fact that it is not sorted shouldn't matter. As far as efficiency
goes, it is all handled by a BIF as opposed to interpreted code, so it
has the opportunity to be more efficient.

Now, I don't know how you want to use the results but this leaves you
with an array containing all the keys that you need for later use.

Thanks. I think I'll go with this one.

[WildernessCat]

On Oct 15, 5:05 pm, Captain Paralytic <[e-mail]:

On 15 Oct, 14:43, WildernessCat <[e-mail]:

On Oct 15, 3:17 pm, Captain Paralytic <[e-mail]:

On 15 Oct, 14:09, WildernessCat <[e-mail]:

Hello there!

Suppose I have an associative array that looks like this:
$arr['alpha_1'] = 'some value';
$arr['alpha_3'] = 'some value';
$arr['alpha_4'] = 'some value';
$arr['beta_2'] = 'some value';
$arr['beta_4'] = 'some value';
$arr['beta_6'] = 'some value';
$arr['gamma_1'] = 'some value';
$arr['gamma_5'] = 'some value';
$arr['gamma_6'] = 'some value';
$arr['gamma_7'] = 'some value';

Let's assume that the array is reasonably large (hundreds of entries).

Is there an efficient way of getting all the items whose key starts
with 'beta'? (without doing a foreach/strncmp loop?)

Thanks in advance,
Danny

Something like:

preg_grep('/^beta/',array_keys($arr));

should give you all the keys that start with 'beta'

Yes, it sure looks more compact in the code, but the question is
whether it's more efficient? I have a gut feeling that there is no
efficient way.

By the way I forgot to mention that the array is not sorted.- Hide quoted text -

- Show quoted text -

The fact that it is not sorted shouldn't matter. As far as efficiency
goes, it is all handled by a BIF as opposed to interpreted code, so it
has the opportunity to be more efficient.

Now, I don't know how you want to use the results but this leaves you
with an array containing all the keys that you need for later use.

Thanks! I think I'll go with this option.