[datatable-help] Report an unexpected behavior in data.table 1.5

[Branson Owen]

Sigh, I gave you some misleading information. I was saying that it
doesn't work within function, and work in global. I was wrong. It
doesn't work even in global in 1.5.

> data.table(A=1:10,B=rnorm(10),key="A")[eval(parse(text="B>0"))]
Error in `[.data.table`(data.table(A = 1:10, B = rnorm(10), key = "A"),  :
  i has not evaluated to logical, integer or double

What I was using eval(...) in global is j expression, i.e.
[,eval(...)] rather than i expression [eval(...)]
data.table(A=1:10,B=rnorm(10),key="A")[,eval(parse(text="B"))]

Apologize for the bothersome information.

Best regards,

2010/9/2 Branson Owen <branson.owen at gmail.com>:
> Alright, my fault. I was reckless again. I forgot my standard R using
> data.table 1.4, and thus the problem doesn't exist. Now, I can give
> you the error example with standard R and appropriate data.table
> version.
>
>> fn <- function(criteria) data.table(A=1:10,B=rnorm(10),key="A")[eval(parse(text=criteria))]
>> fn("B>0")
>
> [data.table 1.5]
>
> Error in `[.data.table`(data.table(A = 1:10, B = norm(10), key = "A"),  :
>  i has not evaluated to logical, integer or double
>
> [data.table 1.4]
>    A      B
> [1,] 3   0.67
> [2,] 4   1.16
> [3,] 6   1.01
> [4,] 8   0.09
>
> Again, the solution is to add {} around eval(...)
>
> ** Discussion of similar problems I have bumped into **
> Is it an environment? namespace? or search.path? problem. (Sorry, at
> this moment I only have rough impression about these concepts)
> Anyway, I have bumped into this kind of problem three times including
> this one. Just want to summarize. Might help identify where the
> problem is.
>
> a. DT[J(unique(COL))]
> This is the bug Matthew just fixed. [...] can't see function defined
> outside. I was using {} wrapper to solve this problem.
>
> b. DT[...] can't see the local variable defined within a function in
> data.table 1.4. This bug is really painful. I have to defined some
> variables outside the function. Make it available in global
> environment. This bug has been fixed in 1.5 before I can report it.
>
> c. the bug I reported in the beginning
>
> The first two bugs belongs to data.table 1.4, and were fixed in
> current version 1.5. Bug (c) doesn't exist in 1.4. Thus, I suspect
> that fixing the (a) and (b) bugs caused the new bug (c)?
>
> Please take your time to look at it if you are interested. This bug is
> really a minor issue compared to bug (b), which I am glad has been
> fixed.
>
> Best regards,
>
> 2010/9/2 Branson Owen <branson.owen at gmail.com>:
>> Ha, I found the problem is caused by the special REvolution R 3.1.1
>> when I tried to re-produce the error. The underlying R is 2.9.2 which
>> is not allowed for data.table 1.5 (I rebuild the package to remove the
>> version restriction). Sorry, I didn't check it on standard R first
>> (Usually, I do.) An embarrassing mistake. :-P I know my working
>> environment is dangerous, and I will upgrade to their new version 4.0
>> soon, which is build on R-2.11.1. It was lucky that putting a {}
>> wrapper can solve my problem.
>>
>> Best regards,
>>
>> 2010/8/31 Matthew Dowle <mdowle at mdowle.plus.com>:
>>> I just have 30 seconds for quick reply ... can see I'll need
>>> reproducible example for this one please; it will probably depend on
>>> contents of 'criteria', columns of DT and arguments of the function
>>> within which it fails. With that I can take a look later ... Thanks.
>>> On Tue, 2010-08-31 at 08:40 -0500, Branson Owen wrote:
>>>> Dear all,
>>>> I just updated my data.table package from 1.4 to 1.5 yesterday. Ran
>>>> into a small problem that has been solved. Just want to report it
>>>> since I don't quite understand it.
>>>> > DT[eval(parse(text = criteria))]
>>>> This command is working in 1.4, but not everywhere in 1.5. It show
>>>> this error message when called within a function.
>>>> Error in `[.data.table`(Data, eval(parse(text = criteria))) :
>>>>   i has not evaluated to logical, integer or double
>>>> However, it works in global environment? My solution for a function
>>>> call is, again, wrap it with {}. Therefore,
>>>>
>>>> > DT[ { eval(parse(text = criteria)) } ]
>>>>
>>>> solved my new problem.
>>>>
>>>> It didn't behave like this in 1.4. I guess this is because of the
>>>> favor Matthew did for me for the DT[ { CJ } ] bug. If nothing can be
>>>> perfect, I pretty much like the current setup. There wasn't many
>>>> eval(), but there are lots of CJ/J in my codes.
>>>>
>>>> Just thought you will be interested. Thank you very much for your
>>>> efforts and great work.
>>>>
>>>> Best regards,
>>
>