php the best way to split string containing pairs of values - php

Question

i have a string in the following format:
$str='a1_b1,a2_b2,a3_b3'
where a and b - some positive numbers. i need to split it to get two strings in format:
'a1,a2,a3' and 'b1,b2,b3'
the very primitive way would be:
$temp=explode(',', $str);
$str1='';
$str2='';
for($i=0;$i<count($temp);$i++){
$temp2=explode('_',$temp[$i]);
$str1.=$temp2[0].',';
$str2.=$temp2[1].',';
}
is it possible to do it more intelligent then just explode in loop?

Answer 1

Not much different from accepted answer but doing it with fewer code
<?php
$str = 'a1_b1,a2_b2,a3_b3';
$temp=explode(',', $str);
foreach($temp as $tem)
list($str_a[], $str_b[])=explode('_',$tem);
$str1 = implode(',', $str_a);
$str2 = implode(',', $str_b);

Answer 2

Probably the easiest way (which also happens to use the least amount of code and no loops) is to make use of PHP's parse_str() function:
// Assuming $str = 'a1_b1,a2_b2,a3_b3'
$str = str_replace([',', '_'], ['&', '='], $str);
parse_str($str, $arr);
// Your key/value pairs are now in $arr
$keys = implode(',', array_keys($arr));
$values = implode(',', array_values($arr));
Of course, parse_str() expects the standard foo=bar&baz=boz format, so if possible, you should use that format instead of foo_bar,baz_boz to save yourself a step. But, if that's not possible, then you can simply use str_replace() like I did above to make the appropriate substitutions.
Note: I used PHP 5.4 short array syntax [...]. If you're using < PHP 5.4, change it to array(...) instead.

Answer 3

The best way would be to organize the formatting of the string so that it doesnt come to this stage where you need to do this. But I'm assuming that you cant do that, therefore posting this question here,
What you did is a good way to do this unless you want to use regex.
$str = 'a1_b1,a2_b2,a3_b3' ;
$exp = explode(',', $str);
$a = array();
$b = array();
foreach($exp as $i)
{
$sep = explode('_', $i);
$a[] = $sep[0];
$b[] = $sep[1];
}
// at this point a and b are arrays so if you want to do better things to the data
// you can use arrays instead of manually concatenating the items with commas
$a_str = implode(',', $a); // a1,a2,a2
$b_str = implode(',', $b); // b1,b2,b2

Answer 4

$temp=explode(',', $str);
$str1='';
$str2='';
$str_a = array();
$str_b = array();
for($i=0;$i<count($temp);$i++){
$temp2=explode('_',$temp[$i]);
$str_a[]=$temp2[0];
$str_b[]=$temp2[1];
}
$str1 = implode(',', $str_a);
$str2 = implode(',', $str_b);
Oh, this is nothing more intelligent...

Answer 5

I can't really think of a better way of doing it. The best thing would be to not get in a situation where you need to do this in the first place but what can we do?
Just to provide another (not better) way of doing the same thing, you can use strtok.
$str='a1_b1,a2_b2,a3_b3';
$tok = strtok($str, "_,");
$i = 0;
$a = array();
$b = array();
while ($tok !== false) {
if ($i++ %2) $b[] = $tok;
else $a[] = $tok;
$tok = strtok("_,");
}
echo implode(',', $a); //a1,a2,a3
echo implode(',', $b); //b1,b2,b3
Your way is more clear and easier to understand, so I'd just stick with it.

Answer 6

Assuming PHP >= 5.3.0:
$str = 'a1_b1,a2_b2,a3_b3';
$array = array_map(function($n) { return explode("_", $n); }, explode(",", $str));
$aString = implode(",", array_map(function($n) { return $n[0]; }, $array));
$bString = implode(",", array_map(function($n) { return $n[1]; }, $array));
var_dump($aString);
var_dump($bString);
Output:
string 'a1,a2,a3' (length=8)
string 'b1,b2,b3' (length=8)
Still looping strictly speaking, but fancier :)

Answer 7

$str = 'a1_b1,a2_b2,a3_b3' ;
$arr = preg_split("/[\s,_]/" , $str);
$str1 = $str2 = '';
for($i=0; $i<count($arr); $i++) {
$str1 .= $arr[$i] ;
if(isset($arr[$i+1]))
$str2 .= $arr[$i+1];
if(isset($arr[$i+2])) {
$str1 .= ',';
$str2 .= ',';
}
$i++;
}