suggested fix for Stockapp

[helgasoft]

The first sample app in https://www.opencpu.org/apps.html is very nice, but not operational due to cancellation of Google Finance API. Here is a suggested fix using data from the good guys at IEX.
The function is still called googledata for easy integration, but deserves the name changed to iexdata.

#' IEX data
#' 
#' Download historical prices for a given stock from IEX
#' 
#' @param ticker stock ticker symbol. E.g. "IBM".
#' @param from start date. Either string or date object.
#' @param to end date. Either string or date object.
#' @return dataframe with historical prices
#' @export
googledata <- function(ticker, from = NULL, to = NULL) {
	library(jsonlite)
	myurl <- paste0('https://api.iextrading.com/1.0/stock/',ticker,'/chart/5y')
	mydata <- fromJSON(myurl)		# data.frame
	if (length(mydata)==0) 
		return(NULL)	# ticker not found
	if (!all( c("date","open","high","low","close","volume") %in% names(mydata))) {
		return(NULL)	# ticker has incomplete column list
	}
	mydata <- subset(mydata, select=c(date,open,high,low,close,volume))
	mydata$date <- as.Date(mydata$date, tz='')
	mydata <- mydata[mydata$date>=as.Date(from) & mydata$date<=as.Date(to),]
	names(mydata) <- c('Date','Open','High','Low','Close','Volume')
	
	return(mydata);
}

# test
test.data <- googledata(ticker='IBM', from='2017-07-07', to='2018-05-07');
library(ggplot2)
qplot(Date, Close, data = test.data, geom = c("line", "smooth"));

[jeroen]

Thanks! Could you do a PR at https://github.com/rwebapps/stockapp ?

[jeroen]

Actually I fixed it already: #317

Thanks for the suggestion!!