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rvestvsaxios

MIT 17 1 1,455
629.3 thousand (month) Nov 22 2014 1.0.4(1 year, 7 months ago)
103,590 14 648 MIT
1.6.7(a month ago) Aug 29 2014 213.6 million (month)

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

axios is a popular JavaScript library that allows you to make HTTP requests from a Node.js environment. It is a promise-based library that works in both the browser and Node.js. It is similar to the Fetch API, but with a more powerful feature set and better browser compatibility.

One of the main benefits of using axios is that it automatically transforms the response data into a JSON object, making it easy to work with.

Axios is known for user-friendly API and support for asynchronous async/await syntax making it very accessible in web scraping.

Example Use


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"
// axios can be used with promises:
axios.get('http://httpbin.org/json')
  .then(response => {
    console.log(response.data);
  })
  .catch(error => {
    console.log(error);
  });

// or async await syntax:
var resp = await axios.get('http://httpbin.org/json');
console.log(resp.data);

// to make requests concurrently Promise.all function can be used:
const results = await Promise.all([
  axios.get('http://httpbin.org/html'),
  axios.get('http://httpbin.org/html'),
  axios.get('http://httpbin.org/html'),
])

// axios also supports other type of requests like POST and even automatically serialize them:
await axios.post('http://httpbin.org/post', {'query': 'hello world'});
// or formdata
const data = {name: 'John Doe', email: 'johndoe@example.com'};

await axios.post('https://jsonplaceholder.typicode.com/users',
    querystring.stringify(data), 
    {
        headers: {
            'Content-Type': 'application/x-www-form-urlencoded'
        }
    }
);

// default values like headers can be configured globally
axios.defaults.headers.common['User-Agent'] = 'webscraping.fyi';
// or for session instance:
const instance = axios.create({
  headers: {"User-Agent": "webscraping.fyi"},
})

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