R/get_facebook_handles.r

In snfagora/MapAgora: R Package for Collecting U.S. Nonprofit Organization Data

#' Parse Facebook handles from a webpage
#'
#' @param website_address An website address of an organization
#' @param google_search_results The default is NULL. If you use a Google search result, use a non-NULL value.
#'
#' @return A list of facebook pages
#' @importFrom xml2 read_html
#' @importFrom rvest html_nodes
#' @importFrom rvest html_attr
#' @importFrom rvest html_text
#' @importFrom dplyr filter
#' @importFrom dplyr distinct
#' @importFrom dplyr pull
#' @importFrom stringr str_replace_all
#' @importFrom stringr str_detect
#' @export

parse_facebook_page_from_page <- function(website_address, google_search_results = NULL) {

  # Whether using Google search
  if (is.null(google_search_results) == TRUE) {
    # Read HTML from website_address
    pg <- read_html(website_address)

    response <- GET(website_address, config(ssl_verifypeer = FALSE, timeout = 10, followlocation = TRUE))

    possible_read <- possibly(read_html, otherwise = "This URL is broken.")

    pg <- possible_read(response)
  } else {
    pg <- google_api_results # Read HTML from Google search results
  }

  # HTML links
  hrefs <- pg %>%
    html_nodes("a") %>%
    html_attr("href")

  # Link texts
  link_texts <- pg %>%
    html_nodes("a") %>%
    html_text()

  # Combined them as a data.frame
  all_links <- data.frame(
    href = tolower(hrefs), # lower cases
    link_text = tolower(link_texts)
  ) # lower cases

  facebook_page <- all_links %>%
    # Find hrefs associated with twitter
    filter(grepl("facebook.com/", href) &
      !grepl("/sharer/", href) & # not the org fb page but a link to share the url
      !grepl("/posts/", href) & # not the org fb page but a post they shared
      !grepl("facebook.com/wix", href)) %>%
    # This is the Wix website dev default
    # Distinct hrefs
    distinct(href) %>%
    pull(href) %>%
    str_replace_all("https://twitter.com/|http://twitter.com/", "")


  # Find whether there's no associated Facebook page
  facebook_page <- ifelse(length(facebook_page) == 0, NA, facebook_page)

  if (is.na(facebook_page) != TRUE) {

    # Remove extra stuff
    ## Separate by a special character then select the substring appears before the special character
    facebook_page <- ifelse(str_detect(facebook_page, "[?]") == TRUE,
      strsplit(facebook_page, "?", fixed = TRUE)[[1]][1], facebook_page
    )

    # Error patterns
    error_patterns <- c("#|@|!")

    ## Remove certain first elements of the string vector
    facebook_page <- ifelse(str_detect(facebook_page, error_patterns),
      gsub("^.", "", facebook_page), facebook_page
    )

    return(facebook_page)
  } else {
    return(facebook_page)
  }
}

#' Parse Facebook handles from an organization website
#'
#' @param website_address An website address of an organization
#'
#' @return A list of Facebook handles
#' @export

find_facebook_page_from_org_page <- function(website_address) {
  facebook_page <- parse_facebook_page_from_page(website_address)

  return(facebook_page)
}