# Re: [Rd] (PR#9202) Re: Bugs with partial name matching

From: Anil Maliyekkel <amaliy1_at_uic.edu>
Date: Wed 06 Sep 2006 - 03:50:30 GMT

On Sep 5, 2006, at 5:54 PM, Thomas Lumley wrote:

```> The problem in
>> D = list(ABCD=2:1)
>>  D\$ABC[]<-3:4
>> D
> \$ABCD
> [1] 3 4
>
> \$ABC
> [1] 3 4
>
> is that eval.c:evalseq ends up with a reference to D\$ABCD from
> evaluating D\$ABC with partial matching.  Since evalseq doesn't (and
> shouldn't) increase NAMED on these partially evaluated calls, NAMED
> is still 1 for D\$ABCD.  When evalseq's D\$ABC has 3:4 assigned into
> it the vector is changed directly, since NAMED=1, and both D\$ABC
> and D\$ABCD change.

```

> D = list(ABCD=2:1)
> D\$ABC[]=c(3,4)
> D
\$ABCD
[1] 2 1

\$ABC
[1] 3 4

Or when this is done:

> D = list(ABCD=2:1)
> D[["ABC"]][]=3:4
> D
\$ABCD
[1] 2 1

\$ABC
[1] 3 4

But it does appear when the following is done:

> D = list(ABCD=2:1)
> X = 3:4
> D\$ABC[]=X
> D

\$ABCD
[1] 3 4

\$ABC
[1] 3 4

But not when the following is done:
> D = list(ABCD=2:1)
> X = 3:4
> X[1] = 1
> D\$ABC[]=X
> D

\$ABCD
[1] 2 1

\$ABC
[1] 1 4

Going back to the original partial replacement problem, is there anyway to turn off partial matching, or to selectively apply exact matching when trying to access a single element? I can get the desired single element match using the convoluted syntax D["ABC"] [[1]] and perform partial replacement operations on a new column. However, it would be nice to have single element access operator that does exact matching.

Anil

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https://stat.ethz.ch/mailman/listinfo/r-devel Received on Wed Sep 06 13:52:56 2006

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