PHP Compound Equation Parser

[RyanJ]

Hi all,

 

Does anyone know of a PHP compound parser that takes a compounds formula as input (e.g. UO2(CO3)) and then spits out an array of the element symbols with the number of each present in the specified formula, in this case U=1, O=5,C=1.

 

Any help appreciated!

[aliu]

Try this:

 

<?php
$input = 'UO2(CO3)';  
$find = array('(', ')');  
$input_clean = str_replace($find, "", $input); // replace '(' and ')' with nothing
$letters = str_split($input_clean);
$letter_counter = array();
$last_char = null;
foreach ($letters as $char) {
	if (preg_match("/\d+/", $char)) {
		$letter_counter["$last_char"] = $letter_counter["$last_char"] + $char - 1;
	}
	else {
		$letter_counter["$char"]++;
	}
	$last_char = $char;
}
var_dump($letter_counter);
?>

 

 

Quickly whipped it up but it works =)

 

Allen

 

Try this:

 

<?php
$input = 'UO2(CO3)';  
$find = array('(', ')');  
$input_clean = str_replace($find, "", $input); // replace '(' and ')' with nothing
$letters = str_split($input_clean);
$letter_counter = array();
$last_char = null;
foreach ($letters as $char) {
	if (preg_match("/\d+/", $char)) {
		$letter_counter["$last_char"] = $letter_counter["$last_char"] + $char - 1;
	}
	else {
		$letter_counter["$char"]++;
	}
	$last_char = $char;
}
var_dump($letter_counter);
?>

 

 

Quickly whipped it up but it works =)

 

Allen

 

Wow...just realized that I was a couple of months too late. Darn!

[Xittenn]

Would that have accounted for elements like Li where it is denoted by two letters. Not that this would be any more difficult to add, in that one would simply have to note the locations of letters that are not capitals. Or search based on a library of known elements!

Edited March 12, 2011 by Xittenn