R/crypto_prices.R

In heguevel/Crypto: Cryptocurrency Market Data

#' @title Get current crypto currency prices
#' @description This will retrieve the current market prices from CoinMarketCap. Data gets refreshed every 5 minutes but will only return 100 at a time.
#' @note The 'offset' parameter can be used to return the next 100 prices
#' @param coin Token name, default is all, Default: NULL
#' @param limit Return top n coins, default is all, Default: 0
#' @param offset Optional number to offset the initial index of listings
#' @param currency Convert into local currency. Must be one of 'AUD', 'BRL', 'CAD', 'CHF', 'CLP', 'CNY', 'CZK', 'DKK', 'EUR', 'GBP', 'HKD', 'HUF', 'IDR', 'ILS', 'INR', 'JPY', 'KRW', 'MXN', 'MYR', 'NOK', 'NZD', 'PHP', 'PKR', 'PLN', 'RUB', 'SEK', 'SGD', 'THB', 'TRY', 'TWD', 'ZAR', Default: NULL
#' @return Will provide data frame of current prices
#' @details Updated every 5 minutes
#' @examples {
#' kin_price <- crypto_prices('kin')
#' }
#' @rdname crypto_prices
#' @export
#' @importFrom jsonlite read_json
#' @import tidyr
crypto_prices <- function(coin = NULL, limit = 0, currency = NULL, offset = NULL) {
  options(scipen = 999)
  url <- "https://api.coinmarketcap.com/v1/ticker/"
  if (is.null(coin)) {
    url <- paste0(url, "?limit=", limit)
  }
  if (!is.null(coin)) {
    url <- paste0(url, coin, "/")
  }
  if (!is.null(currency)) {
    currency <- toupper(currency)
    
    if (is.null(coin)) {
      url <- paste0(url, "&convert=", currency)
    }
    if (!is.null(coin)) {
      url <- paste0(url, "?convert=", currency)
    }
  }
  if (!is.null(offset)) {
    url <- ifelse(grep("\\?", url), paste0(url, "&start=", offset), paste0(url, 
      "?start=", offset))
  }
  prices <- safely_read_json(url)
  prices$market_cap_usd <- prices$market_cap_usd %>% tidyr::replace_na(0) %>% as.numeric()
  prices$available_supply <- prices$available_supply %>% tidyr::replace_na(0) %>% 
    as.numeric()
  prices$max_supply <- prices$max_supply %>% tidyr::replace_na(0) %>% as.numeric()
  prices$total_supply <- prices$total_supply %>% tidyr::replace_na(0) %>% as.numeric()
  cols <- c(4:14)
  prices[, cols] <- apply(prices[, cols], 2, function(x) replace(x, is.na(x), 0))
  prices[, cols] <- suppressWarnings(apply(prices[, cols], 2, function(x) as.numeric(x)))
  prices[, 15] <- as.POSIXct(as.numeric(prices[, 15]), origin = "1970-01-01")
  if (!is.null(currency)) {
    concols <- c(16:18)
    prices[, concols] <- suppressWarnings(apply(prices[, concols], 2, function(x) as.numeric(x)))
  }
  return(prices)
}