php 抓取并输出给定标签中的特定值或数字

Question

所以我对 php 很陌生。但是在一些帮助下，我想出了如何抓取具有 h1 class=____

标签标识符的网站

更好的是，我已经想出了如何输出我想要的精确单词或值，只要它被空白分隔 space。因此，例如，如果给定标签名称 < INVENTORY > 的输出为“30 个球”，我可以指定为 echo[0]，并且只会输出 30 个。太好了。

不过，我运行遇到了一个问题，我是否正在尝试提取一个没有用空格分隔的值 space。所以我的意思是，假设我想要“-34.89”作为输出（更准确地说，网站上该占位符中的任何数字，因为源网站上的数字可能会随时间变化）。

但是，我得到的输出是“-34.89dowjonessstockchange”。那里没有空白 space。

我该怎么做才能输出-34.89？或者，在给定的一天，无论数字是多少。必须有某种方式来表示上面的输出，只输出值 [0,1,2,3,4,5] for ex，就值的数量而言是 -34.89.

下面是一个网站上的测试例子，输出由“”空格决定的词和值space。这几乎是我所需要的，但缺少这种更精确的方法。

// this function is a scraping function for ethereumchange
function getEthereumchange(){
    $doc = new DOMDocument;

    // We don't want to bother with white spaces
    $doc->preserveWhiteSpace = false;


    $doc->strictErrorChecking = false;
    $doc->recover = true;

    $doc->loadHTMLFile('https://coinmarketcap.com/');



    $xpath = new DOMXPath($doc);

    $query = "//tr[@id='id-ethereum']";




    $entries = $xpath->query($query);
    foreach ($entries as $entry) {
        $result = trim($entry->textContent); 
        $ret_ = explode(' ', $result);
        //make sure every element in the array don't start or end with blank
        foreach ($ret_ as $key=>$val){
            $ret_[$key]=trim($val);
        }
        //delete the empty element and the element is blank "\n" "\r" "\t"
        //I modify this line
        $ret_ = array_values(array_filter($ret_,deleteBlankInArray));
            
        //echo the last element
        file_put_contents(globalVars::$_cache_dir . "ethereumchange", 
$ret_[7]);

    }

非常感谢。

Answer 1

如果您只关心那个变化百分比，试试这个并删除整个 foreach 部分：

$query = "//tr[@id='id-ethereum']/td[contains(@class, 'percent-24h')]";
$entries = $xpath->query($query);

echo $entries->item(0)->getAttribute('data-usd'); //-5.15

这是其余的列：

$xpath = new DOMXPath($doc);

$market_cap = $xpath->query("//tr[@id='id-ethereum']/td[contains(@class, 'market-cap')]");
echo $market_cap->item(0)->getAttribute('data-usd'); //30574084827.1


$price = $xpath->query("//tr[@id='id-ethereum']/td/a[contains(@class, 'price')]");
echo $price->item(0)->getAttribute('data-usd'); //329.567

$circulating_supply = $xpath->query("//tr[@id='id-ethereum']/td/a[@data-supply]");
echo $circulating_supply->item(0)->getAttribute('data-supply'); //92770467.9991


$volume = $xpath->query("//tr[@id='id-ethereum']/td/a[contains(@class, 'volume')]");
echo $volume->item(0)->getAttribute('data-usd'); //810454000.0


$percent_change = $xpath->query("//tr[@id='id-ethereum']/td[contains(@class, 'percent-24h')]");
echo $percent_change->item(0)->getAttribute('data-usd'); //-3.79

Answer 2

如果你想使用第三方库你可以使用https://github.com/rajanrx/php-scrape

<?php

use Scraper\Scrape\Crawler\Types\GeneralCrawler;
use Scraper\Scrape\Extractor\Types\MultipleRowExtractor;

require_once(__DIR__ . '/../vendor/autoload.php');
date_default_timezone_set('UTC');

// Create crawler
$crawler = new GeneralCrawler('https://coinmarketcap.com/');

// Setup configuration
$configuration = new \Scraper\Structure\Configuration();
$configuration->setTargetXPath('//table[@id="currencies"]');
$configuration->setRowXPath('.//tbody/tr');
$configuration->setFields(
    [
        new \Scraper\Structure\TextField(
            [
                'name'  => 'Name',
                'xpath' => './/td[2]/a',
            ]
        ),
        new \Scraper\Structure\TextField(
            [
                'name'  => 'Market Cap',
                'xpath' => './/td[3]',
            ]
        ),
        new \Scraper\Structure\RegexField(
            [
                'name'  => '% Change',
                'xpath' => './/td[7]',
                'regex' => '/(.*)%/'
            ]
        ),
    ]
);

// Extract  data
$extractor = new MultipleRowExtractor($crawler, $configuration);
$data = $extractor->extract();
print_r($data);

将打印出以下内容：

Array
(
    [0] => Array
        (
            [Name] => Bitcoin
            [Market Cap] => ,495,710,233
            [% Change] => -1.09
            [hash] => 76faae07da1d2f8c1209d86301d198b3
        )

    [1] => Array
        (
            [Name] => Ethereum
            [Market Cap] => ,063,517,955
            [% Change] => -8.10
            [hash] => 18ade4435c69b5116acf0909e174b497
        )

    [2] => Array
        (
            [Name] => Ripple
            [Market Cap] => ,483,663,781
            [% Change] => -2.73
            [hash] => 5bf61e4bb969c04d00944536e02d1e70
        )

    [3] => Array
        (
            [Name] => Litecoin
            [Market Cap] => ,263,545,508
            [% Change] => -3.36
            [hash] => ea205770c30ddc9cbf267aa5c003933e
        )
   and so on ...

希望对你有所帮助:)

Disclaimer: I am author of this library.

php 抓取并输出给定标签中的特定值或数字

php scraping and outputting a specific value or number in a given tag

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php 抓取并输出给定​​标签中的特定值或数字

php scraping and outputting a specific value or number in a given tag

php

xpath

output

echo

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php 抓取并输出给定标签中的特定值或数字