I'm trying to create a couple of convenience functions for processing data.table objec

enexpr: object not found about tidytable HOT 1 CLOSED

markfairbanks commented on August 20, 2024

enexpr: object not found

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Comments (1)

markfairbanks commented on August 20, 2024

The beginning of your function is testing if(is.null(sel_col_x)) and that's causing the error to occur because it's trying to test if an object named "z" is null. "z" doesn't exist outside of the context of the data.table, but at this point R is still looking for it in the global environment.

So you just need to use enexpr() before you test for NULL.

overlap = function(x, y, sel_col_x=NULL, sel_col_y=NULL){
  sel_col_x <- enexpr(sel_col_x)
  sel_col_y <- enexpr(sel_col_y)
  
  if(any((class(x)) == 'data.table')){
    if(is.null(sel_col_x)){
      stop('sel_col_x cannot be NULL for data.table objects')
    }
    x = tidytable::dt_distinct(x, !!sel_col_x)
    x = tidytable::dt_pull(x, !!sel_col_x)
  }
  if(any((class(y)) == 'data.table')){
    if(is.null(sel_col_y)){
      stop('sel_col_y cannot be NULL for data.table objects')
    }
    y = tidytable::dt_distinct(y, !!sel_col_y)
    y = tidytable::dt_pull(y, !!sel_col_y)
  }
  cat('intersect(x,y):', length(intersect(x,y)), '\n')
  cat('setdiff(x,y):', length(setdiff(x,y)), '\n')
  cat('setdiff(y,x):', length(setdiff(y,x)), '\n')
  cat('union(x,y):', length(union(x,y)), '\n')
}

R can now test if the expression "sel_col_x" is NULL, which it won't be because "z" is being passed, but R no longer looks for "z" in the global environment because it is an expression.

Here's the code for dt_pull(). Notice how in dt_pull.tidytable I use enexpr() on "var" and then test for NULL? That's what you need to do as well.

Hope this makes sense! If you have any other questions let me know.

from tidytable.

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