Call object from function environment in R -

i have function similar one:

function.mean.prod<-function(my.df,my.title){   tmp.df<-data.frame(year=1901:2099,productivity=na)   for(i in 1:199)tmp.df[i,2]<-mean(my.df[,,i],na.rm=t)   ggplot(tmp.df)+     geom_line(aes(tmp.df$year,tmp.df$productivity))+     ylab("productivity in g/c/qm")+     xlab("year")+     ggtitle(my.title) } 

executing get:

error in eval(expr, envir, enclos) : object 'tmp.df' not found 

so interpretation of error message object tmp.df created temporarly inside functions environment , when functions executes loop can't call object.

is correct? how can set environment function able call inside loop? many thanks.