Simple R script to pull historical stock data from Yahoo

yahoo_pull.r

# Revision: 2013-01-09 12:34:09 -0600

getYahooStockUrl <- function(symbol, start, end, type="m") {
  # Creates a Yahoo URL for fetching historical stock data
  #
  # Args:
  #   symbol - the stock symbol for which to fetch data
  #   start - the date (CCYY-MM-DD) to start fetching data
  #   end - the date (CCYY-MM-DD) to finish fetching data
  #   type - daily/monthly data indicator ("d" or "m")
  #
  # Returns:
  #   A Yahoo URL string for fetching historical stock data
  start <- as.Date(start)
  end <- as.Date(end)
  url <- "http://ichart.finance.yahoo.com/table.csv?s=%s&a=%d&b=%s&c=%s&d=%d&e=%s&f=%s&g=%s&ignore=.csv"
  
  sprintf(url,
          toupper(symbol),
          as.integer(format(start, "%m")) - 1,
          format(start, "%d"),
          format(start, "%Y"),
          as.integer(format(end, "%m")) - 1,
          format(end, "%d"),
          format(end, "%Y"),
          type)
}

data <- read.csv(getYahooStockUrl("sbux", "2008-1-1", "2008-12-31"),
                 stringsAsFactors=FALSE)
sbux.monthly <- data[order(data$Date), c('Date', 'Adj.Close')]