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php-spidervsrvest

MIT 6 1 1,325
66 (month) Mar 16 2013 v0.7.2(5 months ago)
1,479 1 22 MIT
Nov 22 2014 612.5 thousand (month) 1.0.4(1 year, 9 months ago)

php-spider is a PHP library for web crawling and scraping. It allows developers to easily navigate and extract data from websites by simulating a web browser's behavior.

  • supports two traversal algorithms: breadth-first and depth-first
  • supports crawl depth limiting, queue size limiting and max downloads limiting
  • supports adding custom URI discovery logic, based on XPath, CSS selectors, or plain old PHP
  • comes with a useful set of URI filters, such as Domain limiting
  • supports custom URI filters, both prefetch (URI) and postfetch (Resource content)
  • supports custom request handling logic
  • supports Basic, Digest and NTLM HTTP authentication. See example.
  • comes with a useful set of persistence handlers (memory, file)
  • supports custom persistence handlers
  • collects statistics about the crawl for reporting
  • dispatches useful events, allowing developers to add even more custom behavior
  • supports a politeness policy

This Spider does not support Javascript.

rvest is a popular R library for web scraping and parsing HTML and XML documents. It is built on top of the xml2 and httr libraries and provides a simple and consistent API for interacting with web pages.

One of the main advantages of using rvest is its simplicity and ease of use. It provides a number of functions that make it easy to extract information from web pages, even for those who are not familiar with web scraping. The html_nodes and html_node functions allow you to select elements from an HTML document using CSS selectors, similar to how you would select elements in JavaScript.

rvest also provides functions for interacting with forms, including html_form, set_values, and submit_form functions. These functions make it easy to navigate through forms and submit data to the server, which can be useful when scraping sites that require authentication or when interacting with dynamic web pages.

rvest also provides functions for parsing XML documents. It includes xml_nodes and xml_node functions, which also use CSS selectors to select elements from an XML document, as well as xml_attrs and xml_attr functions to extract attributes from elements.

Another advantage of rvest is that it provides a way to handle cookies, so you can keep the session alive while scraping a website, and also you can handle redirections with handle_redirects

Example Use


use Example\StatsHandler;
use VDB\Spider\Discoverer\XPathExpressionDiscoverer;
use Symfony\Contracts\EventDispatcher\Event;
use VDB\Spider\Event\SpiderEvents;
use VDB\Spider\Spider;

require_once('example_complex_bootstrap.php');

// Create Spider
$spider = new Spider('http://dmoztools.net');

// Add a URI discoverer. Without it, the spider does nothing. In this case, we want <a> tags from a certain <div>
$spider->getDiscovererSet()->set(new XPathExpressionDiscoverer("//div[@id='catalogs']//a"));

// Set some sane options for this example. In this case, we only get the first 10 items from the start page.
$spider->getDiscovererSet()->maxDepth = 1;
$spider->getQueueManager()->maxQueueSize = 10;

// Let's add something to enable us to stop the script
$spider->getDispatcher()->addListener(
    SpiderEvents::SPIDER_CRAWL_USER_STOPPED,
    function (Event $event) {
        echo "\nCrawl aborted by user.\n";
        exit();
    }
);

// Add a listener to collect stats to the Spider and the QueueMananger.
// There are more components that dispatch events you can use.
$statsHandler = new StatsHandler();
$spider->getQueueManager()->getDispatcher()->addSubscriber($statsHandler);
$spider->getDispatcher()->addSubscriber($statsHandler);

// Execute crawl
$spider->crawl();

// Build a report
echo "\n  ENQUEUED:  " . count($statsHandler->getQueued());
echo "\n  SKIPPED:   " . count($statsHandler->getFiltered());
echo "\n  FAILED:    " . count($statsHandler->getFailed());
echo "\n  PERSISTED:    " . count($statsHandler->getPersisted());

// Finally we could do some processing on the downloaded resources
// In this example, we will echo the title of all resources
echo "\n\nDOWNLOADED RESOURCES: ";
foreach ($spider->getDownloader()->getPersistenceHandler() as $resource) {
    echo "\n - " . $resource->getCrawler()->filterXpath('//title')->text();
}
library("rvest")

# Rvest can use basic HTTP client to download remote HTML:
tree <- read_html("http://webscraping.fyi/lib/r/rvest")
# or read from string:
tree <- read_html('
<div class="products">
  <a href="/product/1">Cat Food</a>
  <a href="/product/2">Dog Food</a>
</div>
')

# to parse HTML trees with rvest we use r pipes (the %>% symbol) and html_element function:
# we can use css selectors:
print(tree %>% html_element(".products>a") %>% html_text())
# "[1] "\nCat Food\nDog Food\n""

# or XPath:
print(tree %>% html_element(xpath="//div[@class='products']/a") %>% html_text())
# "[1] "\nCat Food\nDog Food\n""

# Additionally rvest offers many quality of life functions:
# html_text2 - removes trailing and leading spaces and joins values
print(tree %>% html_element("div") %>% html_text2())
# "[1] "Cat Food Dog Food""

# html_attr - selects element's attribute:
print(tree %>% html_element("div") %>% html_attr('class'))
# "products"

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