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rvestvsgracy

MIT 17 1 1,455
629.3 thousand (month) Nov 22 2014 1.0.4(1 year, 7 months ago)
235 2 1 MIT
1.33.0(a month ago) Feb 05 2023 917 (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

Gracy is an API client library based on httpx that provides an extra stability layer with:

  • Retry logic
  • Logging
  • Connection throttling
  • Tracking/Middleware

In web scraping, Gracy can be a convenient tool for creating scraper based API clients.

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"
# 0. Import
import asyncio
from typing import Awaitable
from gracy import BaseEndpoint, Gracy, GracyConfig, LogEvent, LogLevel

# 1. Define your endpoints
class PokeApiEndpoint(BaseEndpoint):
    GET_POKEMON = "/pokemon/{NAME}" # 👈 Put placeholders as needed

# 2. Define your Graceful API
class GracefulPokeAPI(Gracy[str]):
    class Config:  # type: ignore
        BASE_URL = "https://pokeapi.co/api/v2/" # 👈 Optional BASE_URL
        # 👇 Define settings to apply for every request
        SETTINGS = GracyConfig(
          log_request=LogEvent(LogLevel.DEBUG),
          log_response=LogEvent(LogLevel.INFO, "{URL} took {ELAPSED}"),
          parser={
            "default": lambda r: r.json()
          }
        )

    async def get_pokemon(self, name: str) -> Awaitable[dict]:
        return await self.get(PokeApiEndpoint.GET_POKEMON, {"NAME": name})

    # Note: since Gracy is based on httpx we can customized the used client with custom headers etc"
    def _create_client(self) -> httpx.AsyncClient:
        client = super()._create_client()
        client.headers = {"User-Agent": f"My Scraper"} 
        return client

pokeapi = GracefulPokeAPI()

async def main():
    try:
      pokemon = await pokeapi.get_pokemon("pikachu")
      print(pokemon)

    finally:
        pokeapi.report_status("rich")


asyncio.run(main())

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