>>>>> "PD" == Peter Dalgaard <pda...@gmail.com>
>>>>> on Mon, 26 Jun 2017 20:12:38 +0200 writes:
>> On 26 Jun 2017, at 19:04 , Martin Maechler
>> <maech...@stat.math.ethz.ch> wrote:
>>
>>>>>>> peter dalgaard <pda...@gmail.com> on Mon, 26 Jun
>>>>>>> 2017 13:43:28 +0200 writes:
>>
>>> This seems to be due to changes made by Martin Maechler
>>> in 2008. Presumably this fixed something, but it escapes
>>> my memory.
>>
>> Yes: The change set (svn -c46441) also contains the
>> following NEWS entry
>>
>> BUG FIXES
>>
>> o within(<dataframe>, { ... }) now also works when '...'
>> removes more than one column.
>>
> The odd thing is that the assign-NULL technique used for
> removing a single column, NOW also seems to work for
> several columns in a data frame, so I wonder what the
> bug was back then...
It did not work back then: We have had lots of improvements in
[.data.frame in these almost 9 years.
Indeed, the fix I've committed reverts almost to the previous
first version of within.data.frame (which is from Peter
Dalgaard, for those who don't know).
Martin
>>> However, it seems to have broken the equivalence between
>>> within.list and within.data.frame, so now
>>
>>> within.list <- within.data.frame
>>
>>> does not suffice.
>>
>> There have been many improvements since then, so maybe we
>> can change the code so that the above will work again.
>>
>> Another problem seems that we had no tests of
>> within.list() anywhere... so we will have them now.
>>
>> I've hade an idea that seems to work and even simplify
>> the code.... will get back to the issue later in the
>> evening.
>>
>> Martin
>>
>>
>>> The crux of the matter seems to be that both the
>>> following constructions work for data frames
>>
>>>> aq <- head(airquality) names(aq)
>>> [1] "Ozone" "Solar.R" "Wind" "Temp" "Month" "Day"
>>>> aq[c("Wind","Temp")] <- NULL aq
>>> Ozone Solar.R Month Day 1 41 190 5 1 2 36 118 5 2 3 12
>>> 149 5 3 4 18 313 5 4 5 NA NA 5 5 6 28 NA 5 6
>>>> aq <- head(airquality) aq[c("Wind","Temp")] <-
>>>> vector("list",2) aq
>>> Ozone Solar.R Month Day 1 41 190 5 1 2 36 118 5 2 3 12
>>> 149 5 3 4 18 313 5 4 5 NA NA 5 5 6 28 NA 5 6
>>
>>> However, for lists they differ:
>>
>>>> aq <- as.list(head(airquality)) aq[c("Wind","Temp")] <-
>>>> vector("list",2) aq
>>> $Ozone [1] 41 36 12 18 NA 28
>>
>>> $Solar.R [1] 190 118 149 313 NA NA
>>
>>> $Wind NULL
>>
>>> $Temp NULL
>>
>>> $Month [1] 5 5 5 5 5 5
>>
>>> $Day [1] 1 2 3 4 5 6
>>
>>>> aq <- as.list(head(airquality)) aq[c("Wind","Temp")] <-
>>>> NULL aq
>>> $Ozone [1] 41 36 12 18 NA 28
>>
>>> $Solar.R [1] 190 118 149 313 NA NA
>>
>>> $Month [1] 5 5 5 5 5 5
>>
>>> $Day [1] 1 2 3 4 5 6
>>
>>
>>> -pd
>>
>>>> On 26 Jun 2017, at 04:40 , Hong Ooi via R-devel
>>>> <r-devel@r-project.org> wrote:
>>>>
>>>> The behaviour of within() with list input changes if
>>>> you delete 2 or more variables, compared to deleting
>>>> one:
>>>>
>>>> l <- list(x=1, y=2, z=3)
>>>>
>>>> within(l, { rm(z) }) #$x #[1] 1
>>>> #
>>>> #$y #[1] 2
>>>>
>>>>
>>>> within(l, { rm(y) rm(z) }) #$x #[1] 1
>>>> #
>>>> #$y #NULL
>>>> #
>>>> #$z #NULL
>>>>
>>>>
>>>> When 2 or more variables are deleted, the list entries
>>>> are instead set to NULL. Is this intended?
>>>>
>>>> ______________________________________________
>>>> R-devel@r-project.org mailing list
>>>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>>> --
>>> Peter Dalgaard, Professor, Center for Statistics,
>>> Copenhagen Business School Solbjerg Plads 3, 2000
>>> Frederiksberg, Denmark Phone: (+45)38153501 Office: A
>>> 4.23 Email: pd....@cbs.dk Priv: pda...@gmail.com
>>
>>
>>
>>
>>
>>
>>
>>
PD> -- Peter Dalgaard, Professor, Center for Statistics,
PD> Copenhagen Business School Solbjerg Plads 3, 2000
PD> Frederiksberg, Denmark Phone: (+45)38153501 Office: A
PD> 4.23 Email: pd....@cbs.dk Priv: pda...@gmail.com
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