R语法：<<-为全局变量赋值

例：在函数内部为全局变量赋值

all_predata_time <- data.frame(pd=0.1,Row=1,preRow=0,pt=0.1,stasid='1',InitDate='1');
all_predata_time <- all_predata_time[-1,]

......

stasPowerPre_Time <- function(sid){
    ......
    pred <- forecast(x,h=365)

    predata <- data.frame(pd = as.double(pred$mean))
    predata$Row <-as.integer(row.names(predata));
    predata$preRow <- predata$Row -1;
    predata$pt <- as.double(c(0));
    predata$stasid <- staid;
    predata$InitDate <- maxDate ;
    all_predata_time <<- rbind(all_predata_time,predata)
}

apply(stasList, 1, stasPowerPre_Time)