Scrapen in het echt

Webscraping in Python

Thomas Laetsch

Data Scientist, NYU

DataCamp-site

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

Wat is die div?

# response geladen met HTML van https://www.datacamp.com/courses/all

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

print( len(course_divs) )
>>> 185

course-block inspecteren

first_div = course_divs[0]

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

print( len(children) )
>>> 3

Het eerste kind

first_div = course_divs[0]

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

first_child = children[0]

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

Het tweede kind

first_div = course_divs[0]

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

second_child = children[1]

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

Het vergeten kind

first_div = course_divs[0]

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

third_child = children[2]

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

Lijstjeslief

In één CSS-locator

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

Stapsgewijs

# stap 1: course-blocks
course_divs = response.css('div.course-block')

# stap 2: hyperlink-elementen
hrefs = course_divs.xpath('./a/@href')

# stap 3: links extraheren
links = hrefs.extract()

Naar school gaan

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
...

Links verzameld

Webscraping in Python