R/gets.R

In topiaskarjalainen/SpotR: Some functions to interact with spotify api

#'Retuns a data frame of the users playlists.
#'@param userID The wanted user id as a string
#'@return Returns a dataframe that contains the names of the palylists, the total
#'amount of songs on the list and the spotify URI of the playlist
#'@export
getUserPlayslists <- function(userID) {
  query <- paste("https://api.spotify.com/v1/users/",
                 userID,
                 "/playlists",
                 sep = "")

  df <- buildPlaylistDF(query)
  df$n.songs <- as.numeric(df$n.songs)
  return(df)
}

#' Builds the dataframe.
#' Takes the initial query as an argument
#' @param query URL
buildPlaylistDF <- function(query) {
  thisQ <- GETRequest(query)
  offs <- thisQ[["offset"]]
  size <- thisQ[["total"]]
  df <- data.frame(name = character(size),
                   n.songs = numeric(size),
                   id = character(size),
                   tracks = character(size),
                   stringsAsFactors = FALSE)
  while (TRUE) {
    offs <- thisQ[["offset"]]
    NEXT <- thisQ[["next"]]

    for (i in 1:length(thisQ[["items"]])) {
      playlist <- thisQ[["items"]][[i]]
      line <- c(playlist$name,
                playlist$tracks$total,
                playlist$id,
                playlist$tracks$href)
      df[offs+i,] <- line
    }

    if (is.null(NEXT)) break;

    thisQ <- GETRequest(NEXT)
  }

  return(df)
}


#' Creates a list of data.frames that contain playlist tarcks.
#' @param playlists The data.frame returned by getUserPlaylists function
#' @return A list of data.frames that contain the tracks in the playlists
#' @export
getPlaylistTracks <- function(playlists) {
  theList <- vector("list", length(playlists[, 1]))
  message("Downloading...")
  for (i in 1:length(theList)) {
    traURL <- playlists$tracks[i]
    theList[[i]] <- buildTrackDF(traURL) %>% na.omit()
  }

  names(theList) <- playlists$name
  message("Done!")
  return(theList)
}


#' Hidden function. Builds the data frames that contain the tracks.
#' @param playlistURL An URL
#' @return A dataframe that contains the tracks for the playlist specified
#' by playlistURL
buildTrackDF <- function(playlistURL) {
  thisQ <- GETRequest(playlistURL)
  size <- thisQ[["total"]]

  df <- data.frame(name = character(size),
                   popularity = integer(size),
                   album = character(size),
                   artist = character(size),
                   artist_id = character(size),
                   song_id = character(size),
                   song_uri = character(size),
                   stringsAsFactors = FALSE)

  while (TRUE) {
    offs <- thisQ[["offset"]]
    NEXT <- thisQ[["next"]]

    for (i in 1:length(thisQ[["items"]])) {

      song <- thisQ[["items"]][[i]]$track

      if (song[["is_local"]]) {
        entry <- rep(NA, 7)
        df[offs+i,] <- entry
      } else {

        entry <- c(song$name,
                   as.integer(song$popularity),
                   song[["album"]]$name,
                   song$artists[[1]]$name,
                   song$artists[[1]]$id,
                   song$id,
                   song$uri)
        df[offs+i,] <- entry
      }
    }

    if (is.null(NEXT)) break;

    thisQ <- GETRequest(NEXT)
  }
  df$popularity <- as.numeric(df$popularity)
  return(df)
}