Scraping de verdad

Web scraping en Python

Thomas Laetsch

Data Scientist, NYU

Sitio de DataCamp

https://www.datacamp.com/courses/all

¿Qué es el div?

# response loaded with HTML from https://www.datacamp.com/courses/all

course_divs = response.css('div.course-block')

print( len(course_divs) )
>>> 185

Inspeccionando course-block

first_div = course_divs[0]

children = first_div.xpath('./*')

print( len(children) )
>>> 3

El primer hijo

first_div = course_divs[0]

children = first_div.xpath('./*')

first_child = children[0]

print( first_child.extract() )
>>> <a class=... />

El segundo hijo

first_div = course_divs[0]

children = first_div.xpath('./*')

second_child = children[1]

print( second_child.extract() )
>>> <div class=... />

El hijo olvidado

first_div = course_divs[0]

children = first_div.xpath('./*')

third_child = children[2]

print( third_child.extract() )
>>> <span class=... />

En listas

En un único selector CSS

links = response.css('div.course-block > a::attr(href)').extract()

Paso a paso

# paso 1: bloques de curso
course_divs = response.css('div.course-block')

# paso 2: elementos de enlace
hrefs = course_divs.xpath('./a/@href')

# paso 3: extraer enlaces
links = hrefs.extract()

A la escuela

for l in links:
    print( l )

>>> /courses/free-introduction-to-r
>>> /courses/data-table-data-manipulation-r-tutorial
>>> /courses/dplyr-data-manipulation-r-tutorial
>>> /courses/ggvis-data-visualization-r-tutorial
>>> /courses/reporting-with-r-markdown
>>> /courses/intermediate-r
...

Enlaces conseguidos

Web scraping en Python