It's part of an information retrieval thing I'm doing for school. The plan is to create a hashmap of words using the the first two letters of the word as a key and any words with the two letters saved as a string value. So,
hashmap["ba"] = "bad barley base"
Once I'm done tokenizing a line I take that hashmap, serialize it, and append it to the text file named after the key.
The idea is that if I take my data and spread it over hundreds of files I'll lessen the time it takes to fulfill a search by lessening the density of each file. The problem I am running into is when I'm making 100+ files in each run it happens to choke on creating a few files for whatever reason and so those entries are empty. Is there any way to make this more efficient? Is it worth continuing this, or should I abandon it?
I'd like to mention I'm using PHP. The two languages I know relatively intimately are PHP and Java. I chose PHP because the front end will be very simple to do and I will be able to add features like autocompletion/suggested search without a problem. I also see no benefit in using Java. Any help is appreciated, thanks.
I would use a single file to get and put the serialized string. I would also use json as the serialization.
Put the data
$string = "bad barley base";
$data = explode(" ",$string);
$hashmap["ba"] = $data;
$jsonContent = json_encode($hashmap);
file_put_contents("a-z.txt",$jsonContent);
Get the data
$jsonContent = file_get_contents("a-z.txt");
$hashmap = json_decode($jsonContent);
foreach($hashmap as $firstTwoCharacters => $value) {
if ($firstTwoCharacters == 'ba') {
$wordCount = count($value);
}
}
You didn't explain the problem you are trying to solve. I'm guessing you are trying to make a full text search engine, but you don't have document ids in your hashmap so I'm not sure how you are using the hashmap to find matching documents.
Assuming you want a full text search engine, I would look into using a trie for the data structure. You should be able to fit everything in it without it growing too large. Nodes that match a word you want to index would contain the ids of the documents containing that word.
Related
hello im a newbie in php i am trying make a search function using php but only inside the website without any database
basically if i want to search a string namely "Health" it would display the lines
The Joys of Health
Healthy Diets
This snippet is the only thing i could find if properly coded would output the "lines" i want
$myPage = array("directory.php","pages.php");
$lines = file($myPage[n]);
echo $lines[n];
i havent tried it yet if it would work but before i do i want to ask if there is any better way to do this?
if my files have too many lines wont it stress out the server?
The file() function will return an array. You should use file_get_contents() instead, as it returns a string.
Then, use regular expressions to find specific text within a link.
Your goal is fine but the method you're thinking about is not. the file() function read a file, line by line, and inserts it into an array. This assumes the HTML is well-structured in a human-readable fashion, which is not always the case. However, if you're the one providing the HTML and you make sure the structure is perfectly defined, ok... here you have the example you provided us with but complete (take into account it's the 'wrong' way of solving your problem, but if you want to follow that pattern, it's ok):
function pagesearch($pages, $string) {
if (!empty($pages) && !empty($string)) {
$tags = [];
foreach ($pages as $page) {
if ($lines = file($page)) {
foreach ($lines as $line) {
if (!empty($line)) {
if (mb_strpos($line, $string)) {
$tags[$page][] = $line;
}
}
}
}
}
return $tags;
}
}
This will return you an array with all the pages you referenced with all occurrences of the word you look for, separated by page. As I said, it's not the way you want to solve this, but it's a way.
Hope that helps
Because you do not want to use any database and because the term database is very broad and includes the file-system you want to do a search in some database without having a database.
That makes no sense. In your case one database at least is the file-system. If you can accept the fact that you want to search a database (here your html files) but you do not want to use a database to store anything related to the search (e.g. some index or cached results), then what you suggest is basically how it is working: A real-time, text-based, line-by-line file-search.
Sure it is very rudimentary but as your constraint is "no database", you have already found the only possible way. And yes it will stress your server when used because real-time search is expensive.
Otherwise normally Lucene/Solr is used for the job but that is a database and a server even.
I have two lines of XML data that are attributes but also contain data inside then and they are repeating fields. They are being stored in a SimpleXML variable.
<inputField Type="Name">John Doe</inputField>
<inputField Type="DateOfHire">Tomorrow</inputField>
(Clearly this isnt real data but the syntax is actually in my data and I'm just using string data in them)
Everything that I've seen says to access the data like this, ,which I have tried and it worked perfectly. But my data is dynamic so the data isn't always going to be in the same place, so it doesn't fit my needs.
$xmlFile->inputField[0];
$xmlFile->inputField[1];
This works fine until one of the lines is missing, and I can have anywhere from 0 to 5 lines. So what I was wondering was is there any way that I can access the data by attribute name? So potentially like this.
$xmlFile->inputField['Name'];
or
$xmlFile->inputField->Name;
I use these as examples strictly to illustrate what I'm trying to do, I am aware that neither of the above lines of code are syntactically correct.
Just a note this information is being generated externally so I cannot change the format.
If anyone needs clarification feel free to let me know and would be happy to elaborate.
Maybe like this?
echo $xmlFile->inputField->attributest()->Name;
And what you're using? DOMDocument or simplexml?
You don't say, but I assume you're using SimpleXMLElement?
If you want to access every item, just iterate:
foreach ($xmlFile->inputField as $inputField) { ... }
If you want to access an attribute use array notation:
$inputField['Type']
If you want to access only one specific element, use xpath:
$xmlFile->xpath('inputField[#Type="Name"]');
Perhaps you should read through the basic examples of usage in the SimpleXMLElement documentation?
For example you can a grab a data:
$xmlFile = simplexml_load_file($file);
foreach($xmlFile->inputField as $res) {
echo $res["Name"];
}
I want to extrat the content of a specific div in an external webpage, the div looks like this:
<dt>Win rate</dt><dd><div>50%</div></dd>
My target is the "50%". I'm actually using this php code to extract the content:
function getvalue($parameter,$content){
preg_match($parameter, $content, $match);
return $match[1];
};
$parameter = '#<dt>Score</dt><dd><div>(.*)</div></dd>#';
$content = file_get_contents('https://somewebpage.com');
Everything works fine, the problem is that this method is taking too much time, especially if I've to use it several times with diferents $content.
I would like to know if there's a better (faster, simplier, etc.) way to acomplish the same function? Thx!
You may use DOMDocument::loadHTML and navigate your way to the given node.
$content = file_get_contents('https://somewebpage.com');
$doc = new DOMDocument();
$doc->loadHTML($content);
Now to get to the desired node, you may use method DOMDocument::getElementsByTagName, e.g.
$dds = $doc->getElementsByTagName('dd');
foreach($dds as $dd) {
// process each <dd> element here, extract inner div and its inner html...
}
Edit: I see a point #pebbl has made about DomDocument being slower. Indeed it is, however, parsing HTML with preg_match is a call for trouble; In that case, I'd also recommend looking at event-driven SAX XML parser. It is much more lightweight, faster and less memory intensive as it does not build a tree. You may take a look at XML_HTMLSax for such a parser.
There are basically three main things you can do to improve the speed of your code:
Off load the external page load to another time (i.e. use cron)
On a linux based server I would know what to suggest but seeing as you use Windows I'm not sure what the equivalent would be, but Cron for linux allows you to fire off scripts at certain schedule time offsets - in the background - so not using a browser. Basically I would recommend that you create a script who's sole purpose is to go and fetch the website pages at a particular time offset (depending on how frequently you need to update your data) and then write those webpages to files on your local system.
$listOfSites = array(
'http://www.something.com/page.htm',
'http://www.something-else.co.uk/index.php',
);
$dirToContainSites = getcwd() . '/sites';
foreach ( $listOfSites as $site ) {
$content = file_get_contents( $site );
/// i've just simply converted the URL into a filename here, there are
/// better ways of handling this, but this at least keeps things simple.
/// the following just converts any non letter or non number into an
/// underscore... so, http___www_something_com_page_htm
$file_name = preg_replace('/[^a-z0-9]/i','_', $site);
file_put_contents( $dirToContainSites . '/' . $file_name, $content );
}
Once you've created this script, you then need to set the server up to execute it as regularly as you need. Then you can modify your front-end script that displays the stats to read from local files, this would give a significant speed increase.
You can find out how to read files from a directory here:
http://uk.php.net/manual/en/function.dir.php
Or the simpler method (but prone to possible problems) is just to re-step your array of sites, convert the URLs to file names using the preg_replace above, and then check for the file's existence in the folder.
Cache the result of calculating your statistics
It's quite likely this being a stats page that you'll want to visit it quite frequently (not as frequent as a public page, but still). If the same page is visited more often than the cron-based script is executed then there is no reason to do all the calculation again. So basically all you have to do to cache your output is do something similar to the following:
$cachedVersion = getcwd() . '/cached/stats.html';
/// check to see if there is a cached version of this page
if ( file_exists($cachedVersion) ) {
/// if so, load it and echo it to the browser
echo file_get_contents($cachedVersion);
}
else {
/// start output buffering so we can catch what we send to the browser
ob_start();
/// DO YOUR STATS CALCULATION HERE AND ECHO IT TO THE BROWSER LIKE NORMAL
/// end output buffering and grab the contents so we now have a string
/// of the page we've just generated
$content = ob_get_contents(); ob_end_clean();
/// write the content to the cached file for next time
file_put_contents($cachedVersion, $content);
echo $content;
}
Once you start caching things you need to be aware of when you should delete or clear your cache - otherwise if you don't your stats output will never change. With regards to this situation, the best time to clear your cache is at the point you go and fetch the external web pages again. So you should add this line to the bottom of your "cron" script.
$cachedVersion = getcwd() . '/cached/stats.html';
unlink( $cachedVersion ); /// will delete the file
There are other speed improvements you could make to the caching system (you could even record the modified times of the external webpages and load only when they have been updated) but I've tried to keep things easy to explain.
Don't use a HTML Parser for this situation
Scanning a HTML file for one particular unique value does not require the use of a fully-blown or even lightweight HTML Parser. Using RegExp incorrectly seems to be one of those things that lots of start-up programmers fall into, and is a question that is always asked. This has led to lots of automatic knee-jerk reactions from more experience coders to automatically adhere to the following logic:
if ( $askedAboutUsingRegExpForHTML ) {
$automatically->orderTheSillyPersonToUse( $HTMLParser );
} else {
$soundAdvice = $think->about( $theSituation );
print $soundAdvice;
}
HTMLParsers should be used when the target within the markup is not so unique, or your pattern to match relies on such flimsy rules that it'll break the second an extra tag or character occurs. They should be used to make your code more reliable, not if you want to speed things up. Even parsers that do not build a tree of all the elements will still be using some form of string searching or regular expression notation, so unless the library-code you are using has been compiled in an extremely optimised manner, it will not beat well coded strpos/preg_match logic.
Considering I have not seen the HTML you are hoping to parse, I could be way off, but from what I've seen of your snippet it should be quite easy to find the value using a combination of strpos and preg_match. Obviously if your HTML is more complex and might have random multiple occurances of <dt>Win rate</dt><dd><div>50%</div></dd> it will cause problems - but even so - a HTMLParser would still have the same problem.
$offset = 0;
/// loop through the occurances of 'Win rate'
while ( ($p = stripos ($html, 'win rate', $offset)) !== FALSE ) {
/// grab out a snippet of the surrounding HTML to speed up the RegExp
$snippet = substr($html, $p, $p + 50 );
/// I've extended your RegExp to try and account for 'white space' that could
/// occur around the elements. The following wont take in to account any random
/// attributes that may appear, so if you find some pages aren't working - echo
/// out the $snippet var using something like "echo '<xmp>'.$snippet.'</xmp>';"
/// and that should show you what is appearing that is breaking the RegExp.
if ( preg_match('#^win\s+rate\s*</dt>\s*<dd>\s*<div>\s*([0-9]+%)\s*<#i', $snippet, $regs) ) {
/// once you are here your % value will be in $regs[1];
break; /// exit the while loop as we have found our 'Win rate'
}
/// reset our offset for the next loop
$offset = $p;
}
Gotchas to be aware of
If you are new to PHP, as you state in a comment above, then the above may seem rather complicated - which it is. What you are trying to do is quite complex, especially if you want to do it optimally and fast. However, if you follow throught the code I've given and research any bits that you aren't sure of / haven't heard of (php.net is your friend), it should give you a better understanding of a good way to achieve what you are doing.
Guessing ahead however, here are some of the problems you might face with the above:
File Permission errors - in order to be able to read and write files to and from the local operating system you will need to have the correct permissions to do so. If you find you can not write files to a particular directory it might be that the host you are using wont allow you to do so. If this is the case you can either contact them to ask about how to get write permission to a folder, or if that isn't possible you can easily change the code above to use a database instead.
I can't see my content - when using output buffering all the echo and print commands do not get sent to the browser, they instead get saved up in memory. PHP should automatically output all the stored content when the script exits, but if you use a command like ob_end_clean() this actually wipes the 'buffer' so all the content is erased. This can lead to confusing situations when you know you are echoing something.. but it just isn't appearing.
(Mini Disclaimer :) I've typed all the above manually so you may find there are PHP errors, if so, and they are baffling, just write them back here and StackOverflow can help you out)
Instead of trying to not use preg_match why not just trim your document contents down in size? for example, you could dump everything before <body and everything after </body>. then preg_match will be searching less content already.
Also, you could try to do each one of these processes as a pseudo separate thread, so that way they aren't happening one at a time.
I am using MongoDB and storing files into GridFS using PHP. I am pulling files out via:
$mongo = new Mongo;
$images = $monogo->my_db->getGridFS('images');
$image = $images->findOne('epic-beard-man.png');
$stream = $image->getResource();
Which is cool, because $stream is a PHP resource. The thing I need, is to determine if the stream/resource is binary or text. If it is text, I want to output it, otherwise if it is binary, I don't want to output it.
Is there a magical function like: is_binary($stream)
EDIT
echo get_resource_type($stream);
Returns STREAM. Hum, not very useful.
You cannot check this without actually reading from the resource. You can read the whole thing and look for non-printable characters (which should happen pretty fast if it is an image). You can check for "printability" with ctype_print, which will unfortunately return false for tabs and newlines, so it may not be the best one after all. You can also build your own regex to check the data:
preg_match(':^(\P{Cc}|[\t\n])*$:', $data)
The best and easiest thing to do is however to save the data type, possibly the MIME type, together with the object. That way you do not need to do anything magic at display time.
I think that schemaless databases like MongoDB needs at least as much care in the design stage as relational databases. This is a typical thing to think about when designing a database: what type do my data have?
I am trying to create a database field merge into a document (rtf) using php
i.e if I have a document that starts
Dear Sir,
Customer Name: [customer_name], Date of order: [order_date]
After retrieving the appropriate database record I can use a simple search and replace to insert the database field into the right place.
So far so good.
I would however like to have a little more control over the data before it is replaced. For example I may wish to Title Case it, or convert a delimited string into a list with carriage returns.
I would therefore like to be able to add extra formatting commands to the field to be replaced. e.g.
Dear Sir,
Customer Name: [customer_name, TC], Date of order: [order_date, Y/M/D]
There may be more than one formatting command per field.
Is there a way that I can now search for these strings? The format of the strings is not set in stone, so if I have to change the format then I can.
Any suggestions appreciated.
You could use a templating system like Smarty, that might make your life easier, as you can do {$customer_name|ucwords} or actually put PHP code in your email template.
Try a RegEx and preg_replace_callback:
function replace_param($matches)
{
$parts = explode(',',$matches[0]);
//$parts now contains an array like: customer_name,TC,SE,YMD
// do some substitutions and:
return $text;
}
preg_replace_callback('/\[([^\]]+)\]/','replace_param',$rtf);
You can use explode on it to separate them into array values.
For Example:
$customer_name = 'customer_name, TC';
$get_fields = explode(',', $customer_name);
foreach($get_fields as $value)
{
$new_val = trim($value);
// Now do whatever you want to these in here.
}
Sorry if I'm not understanding you.