I can see that one might regard having sum( sum( 1 ), sum( NULL ) ) == sum( 1 )
be TRUE as a necessary consistency, but going down that road one might expect Bert's v+NULL == v for all numeric vectors also. I have always avoided that construction as poor computing practice, but if NULL is supposed to represent the empty set mathematically [1] then this would seem to follow. [1] https://cran.r-project.org/doc/contrib/de_Jonge+van_der_Loo-Introduction_to_data_cleaning_with_R.pdf -- Sent from my phone. Please excuse my brevity. On March 21, 2018 1:06:46 PM PDT, Bert Gunter <bgunter.4...@gmail.com> wrote: >"I see: consistency with additive identity. " > >Ummm, well: > >> 1+NULL >numeric(0) > >> sum(1,NULL) >[1] 1 > >Of course, there could well be something here I don't get, but that >doesn't >look very consistent to me. However, as I said privately, so long as >the >corner case behavior is documented, which it is, I don't care. > >Cheers, >Bert > > > >Bert Gunter > >"The trouble with having an open mind is that people keep coming along >and >sticking things into it." >-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) > >On Wed, Mar 21, 2018 at 10:26 AM, Boris Steipe ><boris.ste...@utoronto.ca> >wrote: > >> I see: consistency with additive identity. That makes sense. Thanks. >> >> B. >> >> >> > On Mar 21, 2018, at 1:22 PM, peter dalgaard <pda...@gmail.com> >wrote: >> > >> > No. The empty sum is zero. Adding it to another sum should not >change >> it. Nothing audacious about that. This is consistent; other >definitions >> just cause trouble. >> > >> > -pd >> > >> >> On 21 Mar 2018, at 18:05 , Boris Steipe <boris.ste...@utoronto.ca> >> wrote: >> >> >> >> Surely the result of summation of non-existent values is not >defined, >> is it not? And since the NA values have been _removed_, there's >nothing >> left to sum over. In fact, pretending the the result in that case is >zero >> would appear audacious, no? >> >> >> >> Cheers, >> >> Boris >> >> >> >> >> >> >> >> >> >> >> >>> On Mar 21, 2018, at 12:58 PM, Jeff Newmiller ><jdnew...@dcn.davis.ca.us> >> wrote: >> >>> >> >>> What do you mean by "should not"? >> >>> >> >>> NULL means "missing object" in R. The result of the sum function >is >> always expected to be numeric... so NA_real or NA_integer could make >sense >> as possible return values. But you cannot compute on NULL so no, that >> doesn't work. >> >>> >> >>> See the note under the "Value" section of ?sum as to why zero is >> returned when all inputs are removed. >> >>> -- >> >>> Sent from my phone. Please excuse my brevity. >> >>> >> >>> On March 21, 2018 9:03:29 AM PDT, Boris Steipe < >> boris.ste...@utoronto.ca> wrote: >> >>>> Should not the result be NULL if you have removed the NA with >> >>>> na.rm=TRUE ? >> >>>> >> >>>> B. >> >>>> >> >>>> >> >>>> >> >>>>> On Mar 21, 2018, at 11:44 AM, Stefano Sofia >> >>>> <stefano.so...@regione.marche.it> wrote: >> >>>>> >> >>>>> Dear list users, >> >>>>> let me ask you this trivial question. I worked on that for a >long >> >>>> time, by now. >> >>>>> Suppose to have a data frame with NAs and to sum some columns >with >> >>>> rowSums: >> >>>>> >> >>>>> df <- data.frame(A = runif(10), B = runif(10), C = rnorm(10)) >> >>>>> df[1, ] <- NA >> >>>>> rowSums(df[ , which(names(df) %in% c("A","B"))], na.rm=T) >> >>>>> >> >>>>> If all the elements of the selected columns are NA, rowSums >returns 0 >> >>>> while I need NA. >> >>>>> Is there an easy and efficient way to use rowSums within a >function >> >>>> like >> >>>>> >> >>>>> function(x) ifelse(all(is.na(x)), as.numeric(NA), rowSums...)? >> >>>>> >> >>>>> or an equivalent function? >> >>>>> >> >>>>> Thank you for your help >> >>>>> Stefano >> >>>>> >> >>>>> >> >>>>> >> >>>>> (oo) >> >>>>> --oOO--( )--OOo---------------- >> >>>>> Stefano Sofia PhD >> >>>>> Area Meteorologica e Area nivologica - Centro Funzionale >> >>>>> Servizio Protezione Civile - Regione Marche >> >>>>> Via del Colle Ameno 5 >> >>>>> 60126 Torrette di Ancona, Ancona >> >>>>> Uff: 071 806 7743 >> >>>>> E-mail: stefano.so...@regione.marche.it >> >>>>> ---Oo---------oO---------------- >> >>>>> >> >>>>> ________________________________ >> >>>>> >> >>>>> AVVISO IMPORTANTE: Questo messaggio di posta elettronica può >> >>>> contenere informazioni confidenziali, pertanto è destinato solo >a >> >>>> persone autorizzate alla ricezione. I messaggi di posta >elettronica >> per >> >>>> i client di Regione Marche possono contenere informazioni >> confidenziali >> >>>> e con privilegi legali. Se non si è il destinatario specificato, >non >> >>>> leggere, copiare, inoltrare o archiviare questo messaggio. Se si >è >> >>>> ricevuto questo messaggio per errore, inoltrarlo al mittente ed >> >>>> eliminarlo completamente dal sistema del proprio computer. Ai >sensi >> >>>> dell’art. 6 della DGR n. 1394/2008 si segnala che, in caso di >> necessità >> >>>> ed urgenza, la risposta al presente messaggio di posta >elettronica può >> >>>> essere visionata da persone estranee al destinatario. >> >>>>> IMPORTANT NOTICE: This e-mail message is intended to be >received only >> >>>> by persons entitled to receive the confidential information it >may >> >>>> contain. E-mail messages to clients of Regione Marche may >contain >> >>>> information that is confidential and legally privileged. Please >do not >> >>>> read, copy, forward, or store this message unless you are an >intended >> >>>> recipient of it. If you have received this message in error, >please >> >>>> forward it to the sender and delete it completely from your >computer >> >>>> system. >> >>>>> >> >>>>> -- >> >>>>> Questo messaggio stato analizzato da Libra ESVA ed risultato >non >> >>>> infetto. >> >>>>> This message was scanned by Libra ESVA and is believed to be >clean. >> >>>>> >> >>>>> >> >>>>> [[alternative HTML version deleted]] >> >>>>> >> >>>>> ______________________________________________ >> >>>>> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, >see >> >>>>> https://stat.ethz.ch/mailman/listinfo/r-help >> >>>>> PLEASE do read the posting guide >> >>>> http://www.R-project.org/posting-guide.html >> >>>>> and provide commented, minimal, self-contained, reproducible >code. >> >>>> >> >>>> ______________________________________________ >> >>>> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, >see >> >>>> https://stat.ethz.ch/mailman/listinfo/r-help >> >>>> PLEASE do read the posting guide >> >>>> http://www.R-project.org/posting-guide.html >> >>>> and provide commented, minimal, self-contained, reproducible >code. >> >> >> >> ______________________________________________ >> >> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >> >> https://stat.ethz.ch/mailman/listinfo/r-help >> >> PLEASE do read the posting guide http://www.R-project.org/ >> posting-guide.html >> >> and provide commented, minimal, self-contained, reproducible code. >> > >> > -- >> > 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 >> > >> > >> > >> > >> > >> > >> > >> > >> > >> >> ______________________________________________ >> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide http://www.R-project.org/ >> posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. >> ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
