scrapeR is a framework inspired by the scrapy python framework. It is meant to be used for batching multiple crawlers and reusing item pipelines between them.
The basic components of a scrapeR project are queues, steps, pipelines, and runners.
Pipelines are an organizational tool of a combination of different scraping and processing steps that are applied to the original queue of data. Each pipeline begins with a list input and will run each step in the pipeline. Pipelines can steps are similar to classic functional programming functions but have the advantage of delayed execution, reusability, parallelization, and documentation.
The steps that comprise pipelines can either be parsers or transformers. Parsers are steps that are applied to each item of the queue in parallel. Transformers are steps that are applied to entire queue and are important for summarizing and consolidating the results.
# Install the development version from GitHub:
# install.packages("devtools")
devtools::install_github("quartzsoftwarellc/scrapeR")
library(rvest)
library(scrapeR)
start_url <- "https://en.wikipedia.org/wiki/Cat"
spider("cats") %>%
add_queue(start_url) %>%
add_parser(~ {
read_html(.x) %>%
html_nodes(".mw-headline") %>%
html_text()
}
) %>%
run() %>%
paste(sep = "")## [1] "Etymology and naming" "Taxonomy"
## [3] "Evolution" "Domestication"
## [5] "Characteristics" "Size"
## [7] "Skeleton" "Skull"
## [9] "Claws" "Ambulation"
## [11] "Balance" "Senses"
## [13] "Vision" "Hearing"
## [15] "Smell" "Taste"
## [17] "Whiskers" "Behavior"
## [19] "Sociability" "Communication"
## [21] "Grooming" "Fighting"
## [23] "Hunting and feeding" "Play"
## [25] "Reproduction" "Lifespan and health"
## [27] "Disease" "Ecology"
## [29] "Habitats" "Ferality"
## [31] "Impact on wildlife" "Interaction with humans"
## [33] "Shows" "Infection"
## [35] "History and mythology" "Superstitions and rituals"
## [37] "Coats" "See also"
## [39] "References" "External links"