[datatable-help] := when i is all false overwrites all values?

[Matthew Dowle]

Oops, that's a bug. Yes, please raise it on tracker.

Neither does this work correctly :

> dt[FALSE,y:=6L]
       x y
 [1,]  1 6
 [2,]  2 6
 [3,]  3 6
 [4,]  4 6
 [5,]  5 6
 [6,]  6 6
 [7,]  7 6
 [8,]  8 6
 [9,]  9 6
[10,] 10 6
> 


On Wed, 2011-08-31 at 15:23 -0400, Chris Neff wrote:
> I didn't submit a bug report quite yet because I didn't know if this
> was intended. Here is a simple example:
> 
> > dt <- data.table(x=1:10,y=1:10)
> > dt[x==0]
> NULL data table
> > dt[x==0, y:=5L]
>        x y
>  [1,]  1 5
>  [2,]  2 5
>  [3,]  3 5
>  [4,]  4 5
>  [5,]  5 5
>  [6,]  6 5
>  [7,]  7 5
>  [8,]  8 5
>  [9,]  9 5
> [10,] 10 5
> 
> I would expect the result to be that no values of y get changed.  This
> is running the latest version from SVN. Is this working as intended?
> 
> -Chris
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