Indexing a dataframe with $ inside a function?

Question

Many R textbooks encourage the use of $ to retrieve variables (columns) from data.frames^. However, I found that this does not work inside a function, and I can\'t figure out wh

Answer 1

You can use also [[ instead of $

myFunc2 <- function(x, y){
+     z <- x[[y]]
+     return(z)
+ }
> myFunc2(BOD, 'demand')
[1]  8.3 10.3 19.0 16.0 15.6 19.8