MongoDB / PHP / MapReduce / Reg Exp / Strings->Floats - php

Question

I'm new with MapReduce, but I have a collection that I'd like to apply myself to as a chance to learn how mapreduce works.
Example Documents:
{ "filename" : "resume.doc",
"folder" : "work",
"completed": "0.5" },
{ "filename" : "spreadsheet.xls",
"folder" : "work",
"completed": "0.6" },
{ "filename" : "thesis.doc",
"folder" : "school",
"completed": "0.75" },
{ "filename" : "coverletter.doc",
"folder" : "work",
"completed": "0.6"}
So the whole idea is: I'd like to query:
{ "folder" : "work",
"completed": { $gt: 0.5 },
"filename" : new MongoRegex( "/\.[a-zA-Z]{2,}$/" ) }
And ultimately get the count of all documents by extension (.doc, .xls, etc.), as so:
{ ".doc" : 1,
".xls" : 1 }
I also realize i've got an issue because my %-completed are strings, not floats, so i think mongodb is going to need more instruction for comparing the strings.
I'm using (if it matters):
PHP extension: mongo/1.5.7
MongoDB: version 3.2.11

Answer 1

Seems I've stumbled upon my own answer.
Let me know if anybody comes up with a more concise/expert solution.
But this seems to work.
try {
$map = new MongoCode(
'function(){
var re = new RegExp(/(.+)\.([a-zA-Z]{2,})$/);
doctype = this.value.match(re);
if(parseFloat(this.completed)>0.5){
emit(doctype[2], parseFloat(this.completed));
}
}'
);
$reduce = new MongoCode(
'function(key, values){
var sum = 0, num = 0;
for(var i in values){
if(parseFloat(values[i])>0.5){
sum += values[i];
num += 1;
}
}
return { number_of_documents : num,
sum_of_document_completions : sum,
average_completion : (sum/num) };
}'
);
$query = array (
"folder" => "work"
);
$doctypes = $db->command(
array(
'mapReduce' => 'mydocuments',
"map" => $map,
"reduce" => $reduce,
"query" => $query,
"out" => array("inline"=>1)
)
);
print_r ( $doctypes);
}
catch(MongoCursorException $e) {
echo "error message: ".$e->getMessage()."\n";
echo "error code: ".$e->getCode()."\n";
}