How to download multiple files with the same name from html page? - r

Question

I want to download all the files named "listings.csv.gz" which refer to US cities from http://insideairbnb.com/get-the-data.html, I can do it by writing each link but is it possible to do in a loop?
In the end I'll keep only a few columns from each file and merge them into one file.
Since the problem was solved thanks to #CodeNoob I'd like to share how it all worked out:
page <- read_html("http://insideairbnb.com/get-the-data.html")
# Get all hrefs (i.e. all links present on the website)
links <- page %>%
html_nodes("a") %>%
html_attr("href")
# Filter for listings.csv.gz, USA cities, data for March 2019
wanted <- grep('listings.csv.gz', links)
USA <- grep('united-states', links)
wanted.USA = wanted[wanted %in% USA]
wanted.links <- links[wanted.USA]
wanted.links = grep('2019-03', wanted.links, value = TRUE)
wanted.cols = c("host_is_superhost", "summary", "host_identity_verified", "street",
"city", "property_type", "room_type", "bathrooms",
"bedrooms", "beds", "price", "security_deposit", "cleaning_fee",
"guests_included", "number_of_reviews", "instant_bookable",
"host_response_rate", "host_neighbourhood",
"review_scores_rating", "review_scores_accuracy","review_scores_cleanliness",
"review_scores_checkin" ,"review_scores_communication",
"review_scores_location", "review_scores_value", "space",
"description", "host_id", "state", "latitude", "longitude")
read.gz.url <- function(link) {
con <- gzcon(url(link))
df <- read.csv(textConnection(readLines(con)))
close(con)
df <- df %>% select(wanted.cols) %>%
mutate(source.url = link)
df
}
all.df = list()
for (i in seq_along(wanted.links)) {
all.df[[i]] = read.gz.url(wanted.links[i])
}
all.df = map(all.df, as_tibble)

Answer 1

You can actually extract all links, filter for the ones containing listings.csv.gz and then download these in a loop:
library(rvest)
library(dplyr)
# Get all download links
page <- read_html("http://insideairbnb.com/get-the-data.html")
# Get all hrefs (i.e. all links present on the website)
links <- page %>%
html_nodes("a") %>%
html_attr("href")
# Filter for listings.csv.gz
wanted <- grep('listings.csv.gz', links)
wanted.links <- links[wanted]
for (link in wanted.links) {
con <- gzcon(url(link))
txt <- readLines(con)
df <- read.csv(textConnection(txt))
# Do what you want
}
Example: Download and combine the files
To get the result you want I would suggest to write a download function that filters for the columns you want and then combines these in a single dataframe, for example something like this:
read.gz.url <- function(url) {
con <- gzcon(url(link))
df <- read.csv(textConnection(readLines(con)))
close(con)
df <- df %>% select(c('calculated_host_listings_count_shared_rooms', 'cancellation_policy' )) %>% # random columns I chose
mutate(source.url = url) # You may need to remember the origin of each row
df
}
all.df <- do.call('rbind', lapply(head(wanted.links,2), read.gz.url))
Note I only tested this on the first two files since they are pretty large