Converting words to numbers in PHP
There are lots of pages discussing the conversion from numbers to words. Not so many for the reverse direction. The best I could find was some pseudo-code on Ask Yahoo. See http://answers.yahoo.com/question/index?qid=20090216103754AAONnDz for a nice algorithm:
Well, overall you are doing two things: Finding tokens (words that translates to numbers) and applying grammar. In short, you are building a parser for a very limited language.
The tokens you would need are:
POWER: thousand, million, billion
HUNDRED: hundred
TEN: twenty, thirty... ninety
UNIT: one, two, three, ... nine,
SPECIAL: ten, eleven, twelve, ... nineteen(drop any "and"s as they are meaningless. Break hyphens into two tokens. That is sixty-five should be processed as "sixty" "five")
Once you've tokenized your string, move from RIGHT TO LEFT.
Grab all the tokens from the RIGHT until you hit a POWER or the whole string.
Parse the tokens after the stop point for these patterns:
SPECIAL
TEN
UNIT
TEN UNIT
UNIT HUNDRED
UNIT HUNDRED SPECIAL
UNIT HUNDRED TEN
UNIT HUNDRED UNIT
UNIT HUNDRED TEN UNIT(This assumes that "seventeen hundred" is not allowed in this grammar)
This gives you the last three digits of your number.
If you stopped at the whole string you are done.
If you stopped at a power, start again at step 1 until you reach a higher POWER or the whole string.
Old question, but for anyone else coming across this I had to write up a solution to this today. The following takes a vaguely similar approach to the algorithm described by John Kugelman, but doesn't apply as strict a grammar; as such it will permit some weird orderings, e.g. "one hundred thousand and one million" will still produce the same as "one million and one hundred thousand" (1,100,000). Invalid bits (e.g. misspelled numbers) will be ignored, so the consider the output on invalid strings to be undefined.
Following user132513's comment on joebert's answer, I used Pear's Number_Words to generate test series. The following code scored 100% on numbers between 0 and 5,000,000 then 100% on a random sample of 100,000 numbers between 0 and 10,000,000 (it takes to long to run over the whole 10 billion series).
/**
* Convert a string such as "one hundred thousand" to 100000.00.
*
* @param string $data The numeric string.
*
* @return float or false on error
*/
function wordsToNumber($data) {
// Replace all number words with an equivalent numeric value
$data = strtr(
$data,
array(
'zero' => '0',
'a' => '1',
'one' => '1',
'two' => '2',
'three' => '3',
'four' => '4',
'five' => '5',
'six' => '6',
'seven' => '7',
'eight' => '8',
'nine' => '9',
'ten' => '10',
'eleven' => '11',
'twelve' => '12',
'thirteen' => '13',
'fourteen' => '14',
'fifteen' => '15',
'sixteen' => '16',
'seventeen' => '17',
'eighteen' => '18',
'nineteen' => '19',
'twenty' => '20',
'thirty' => '30',
'forty' => '40',
'fourty' => '40', // common misspelling
'fifty' => '50',
'sixty' => '60',
'seventy' => '70',
'eighty' => '80',
'ninety' => '90',
'hundred' => '100',
'thousand' => '1000',
'million' => '1000000',
'billion' => '1000000000',
'and' => '',
)
);
// Coerce all tokens to numbers
$parts = array_map(
function ($val) {
return floatval($val);
},
preg_split('/[\s-]+/', $data)
);
$stack = new SplStack; // Current work stack
$sum = 0; // Running total
$last = null;
foreach ($parts as $part) {
if (!$stack->isEmpty()) {
// We're part way through a phrase
if ($stack->top() > $part) {
// Decreasing step, e.g. from hundreds to ones
if ($last >= 1000) {
// If we drop from more than 1000 then we've finished the phrase
$sum += $stack->pop();
// This is the first element of a new phrase
$stack->push($part);
} else {
// Drop down from less than 1000, just addition
// e.g. "seventy one" -> "70 1" -> "70 + 1"
$stack->push($stack->pop() + $part);
}
} else {
// Increasing step, e.g ones to hundreds
$stack->push($stack->pop() * $part);
}
} else {
// This is the first element of a new phrase
$stack->push($part);
}
// Store the last processed part
$last = $part;
}
return $sum + $stack->pop();
}
I haven't tested this too extensively, I more or less just worked on it until I saw what I expected in the output, but it seems to work, and parses from left-to-right.
<?php
$str = 'twelve billion people know iPhone has two hundred and thirty thousand, seven hundred and eighty-three apps as well as over one million units sold';
function strlen_sort($a, $b)
{
if(strlen($a) > strlen($b))
{
return -1;
}
else if(strlen($a) < strlen($b))
{
return 1;
}
return 0;
}
$keys = array(
'one' => '1', 'two' => '2', 'three' => '3', 'four' => '4', 'five' => '5', 'six' => '6', 'seven' => '7', 'eight' => '8', 'nine' => '9',
'ten' => '10', 'eleven' => '11', 'twelve' => '12', 'thirteen' => '13', 'fourteen' => '14', 'fifteen' => '15', 'sixteen' => '16', 'seventeen' => '17', 'eighteen' => '18', 'nineteen' => '19',
'twenty' => '20', 'thirty' => '30', 'forty' => '40', 'fifty' => '50', 'sixty' => '60', 'seventy' => '70', 'eighty' => '80', 'ninety' => '90',
'hundred' => '100', 'thousand' => '1000', 'million' => '1000000', 'billion' => '1000000000'
);
preg_match_all('#((?:^|and|,| |-)*(\b' . implode('\b|\b', array_keys($keys)) . '\b))+#i', $str, $tokens);
//print_r($tokens); exit;
$tokens = $tokens[0];
usort($tokens, 'strlen_sort');
foreach($tokens as $token)
{
$token = trim(strtolower($token));
preg_match_all('#(?:(?:and|,| |-)*\b' . implode('\b|\b', array_keys($keys)) . '\b)+#', $token, $words);
$words = $words[0];
//print_r($words);
$num = '0'; $total = 0;
foreach($words as $word)
{
$word = trim($word);
$val = $keys[$word];
//echo "$val\n";
if(bccomp($val, 100) == -1)
{
$num = bcadd($num, $val);
continue;
}
else if(bccomp($val, 100) == 0)
{
$num = bcmul($num, $val);
continue;
}
$num = bcmul($num, $val);
$total = bcadd($total, $num);
$num = '0';
}
$total = bcadd($total, $num);
echo "$total:$token\n";
$str = preg_replace("#\b$token\b#i", number_format($total), $str);
}
echo "\n$str\n";
?>