如何在R中打印最近2个每日开盘价的变化

Question

到目前为止，我的代码如下：

companyList <- read.csv("~/Downloads/companylist.csv")

ticker <- as.vector(as.character(companyList[1:10, 'Symbol']))

stockData <- new.env()

x <- 1

while(x<11){
getSymbols(ticker[x], auto.assign = TRUE, env = stockData)
x <- x + 1
}

data <- getSymbols(ticker[1], auto.assign = FALSE, env = stockData)

val1 <- data[1, 'FLWS.Open']
val2 <- data[2, 'FLWS.Open']

change <- val2 - val1

print(change)

当我尝试打印每日2个开放值的变化时，没有任何显示。我的语法是否有错误？