mysterious .N object in global environment after installing R package

Question

I have created a package for personal use that has some dependencies:

Depends: R (>= 3.2.3), data.table (>= 1.9.6), bit64 (>= 0.9.5), 
         ggplot2 (>= 2.0.0), yaml (>= 2.1.13)

When I install this package via devtools::install() it completes with no error.

When I load the package in a fresh session via library(somePackage) I get the cryptic message:

Attaching package: ‘data.table’

The following object is masked by ‘.GlobalEnv’:

.N

There are no objects in the global environment -- I try ls(), which returns an empty string, clear workspace [broom icon], etc. Yet:

> .N
[1] 100419

which has no meaning to me -- I know what .N is in data.table but have no idea where 100419 came from. How can I tell which environment in the search path this is really going to?

> search()
 [1] ".GlobalEnv"           "package:somePackage"  "package:devtools"     "package:yaml"        
 [5] "package:ggplot2"      "package:bit64"        "package:bit"          "package:data.table"  
 [9] "tools:rstudio"        "package:stats"        "package:graphics"     "package:grDevices"   
[13] "package:utils"        "package:datasets"     "package:methods"      "Autoloads"           
[17] "package:base"  

I believe that the dependencies are part of the cause, because when I remove this line from the DESCRIPTION file, I do not have this problem.

Running devtools 1.10.0 on R 3.2.3 for Windows.

update: thanks to the hint from @MrFlick:

> ls(all.names=TRUE)
[1] ".N"           ".Random.seed"

So it is in the global environment, but how did it get there and why does it take precedence?

Answer 1

I had the same message when loading data.table. No idea when I loaded .N so I went for the following:

1. Checking all variables to see what I have:

   ls(all.names=TRUE)

2. Removing all varaibles:

   rm(list = ls(all.names=TRUE))