r-仪器类构造函数中的Quantstrat错误

Question

HI我正在尝试复制Ilya Kipnis的"quantstrat i的螺母和螺栓"中的代码。我加载了以下代码：

 require(quantstrat)
 require(PerformanceAnalytics)
 initDate="1990-01-01"
 from="2003-01-01"
 to="2012-12-31"
 options(width=70)
 options("getSymbols.warning4.0"=FALSE)
 currency=('USD')
 Sys.setenv(TZ="UTC")
 symbols<- c("XLB","XLE","XLF","XLP".....
  if(!"XLB" %in% ls()) { 
  suppressMessages(getSymbols(symbols, from=from, to=to, src="yahoo",    adjust=TRUE))  
  }
 stock(symbols, currency="USD", multiplier=1)

但是得到以下错误？

  Error in instrument(primary_id = primary_id, currency = currency,   multiplier = multiplier,  : 
  currency USD must be defined first

任何帮助都将不胜感激

Answer 1

定义货币

应使用currency(‘USD’)而非

currency=(‘USD’)，如上的代码