data.table does not play well with checkUsage

data.table, r

Solution

UPDATE : Now resolved in v1.8.11. From NEWS :

`.SD`,`.N`,`.I`,`.GRP` and `.BY` are now exported (as `NULL`). So that NOTEs aren't produced for them by `R CMD check` or `codetools::checkUsage` via `compiler::enableJIT()`. `utils::globalVariables()` was considered, but exporting chosen. Thanks to Sam Steingold for raising, #2723.

And to resolve the notes for the column name symbols `count` and `a`, they can both be wrapped with quotes (even on the LHS of `:=`). Using a fresh R session (since the notes were first time only) the following now produces no notes.

$ R
R version 3.0.1 (2013-05-16) -- "Good Sport"
Copyright (C) 2013 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)
> require(data.table)
Loading required package: data.table
data.table 1.8.11  For help type: help("data.table")
> library(compiler)
> compiler::enableJIT(3)
[1] 0
> dt <- data.table(a=c(rep(3,5),rep(4,5)), b=1:10, c=11:20, d=21:30, key="a")
> my.func <- function (dt) {
  dt.out <- dt[, lapply(.SD, sum), by = "a"]
  dt.out[, "count" := dt[, .N, by="a"]$N]
  dt.out
}
> my.func(dt)
   a  b  c   d count
1: 3 15 65 115     5
2: 4 40 90 140     5
> checkUsage(my.func)
>

Problem

`data.table` is a wonderful package, which, alas, generates unwarranted warnings from `checkUsage` (the code comes from here and here): ``` > library(compiler) > compiler::enableJIT(3) > dt <- data.table(a = c(rep(3, 5), rep(4, 5)), b=1:10, c=11:20, d=21:30, key="a") > my.func <- function (dt) { dt.out <- dt[, lapply(.SD, sum), by = a] dt.out[, count := dt[, .N, by=a]$N] dt.out } > checkUsage(my.func) <anonymous>: no visible binding for global variable ‘.SD’ (:2) <anonymous>: no visible binding for global variable ‘a’ (:2) <anonymous>: no visible binding for global variable ‘count’ (:3) <anonymous>: no visible binding for global variable ‘.N’ (:3) <anonymous>: no visible binding for global variable ‘a’ (:3) > my.func(dt) Note: no visible binding for global variable '.SD' Note: no visible binding for global variable 'a' Note: no visible binding for global variable 'count' Note: no visible binding for global variable '.N' Note: no visible binding for global variable 'a' a b c d count 1: 3 15 65 115 5 2: 4 40 90 140 5 ``` The warnings about `a` can be avoided by replacing `by=a` with `by="a"`, but how do I deal with the other 3 warnings? This matters to me because these warnings clutter the screen and obscure legitimate warnings. Since the warnings are issued on `my.func` invocation (when JIT compiler is enabled), not just by `checkUsage`, I am inclined to call this a bug.

Original source

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