Questions about the magic.wand function and the piping operators

[samygero]

I want to use the plyrmr package while keeping my existent code written in dplyr and thus I want to use the "magic.wand" function. I am using the "mtcars" dataset for simplicity and the the path to it is "/user/sgerony/mtcars" on the HDFS (Hadoop Distributed File System).

The block of code contains base functions but also dplyr functions and this is my code:

magic.wand(rename,TRUE)
filename <- "/user/sgerony/mtcars"
complex.function = function(x){
  x$carb <- x[,ncol(x)]*2 
  x$carb <- x$carb+2
  x <- as.data.frame(rename(x, lol=carb))
  return(x)
}
magic.wand(complex.function)
# does NOT work
input(filename) %|% complex.function()

Question 1: Is this the right way to do? meaning do I have to call a first time the magic.wand for the dplyr functions and then for the bloc of code?

Question 2: Why can't I call the magic.wand function like this?

magic.wand(dplyr::rename,TRUE)

Isn't it necessary to be sure that we are not using functions contained in several libraries?

Question 3: Why do I have to put "TRUE" as a second argument of the first magic.wand call and not the last one?

Question 4: What if my block of code is using the dplyr piping operator? namely:

complex.function = function(x){
      x$carb <- x[,ncol(x)]*2 
      x$carb <- x$carb+2
      x <- as.data.frame(x %>% rename(lol=carb))
      return(x)
    }

Should I just replace the "%>%" by the plyrmr piping operator? Namely "%|%"?

Question 5: Should I call the magic.wand function on dplyr functions that are equivalent to plyrmr functions like "group_by"?

Question 6: Why do I have an error when using as.POSIXct?

magic.wand(mutate,TRUE)
filename <- "/user/sgerony/mtcars"
complex.function = function(x){
  x$carb <- x[,ncol(x)]*2 
  x$carb <- x$carb+2
  x <- as.data.frame(mutate(x,date.time=as.POSIXct("2014-01-01 03:15")))
  return(x)
}
magic.wand(complex.function)

#Works
mtcars %|% complex.function()
# does NOT work
input(filename) %|% complex.function()

I realize this is a big question, so thanks for trying to help