# by function with sum does not give what is expected from by function with print

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## by function with sum does not give what is expected from by function with print

 Colleagues,   The by function in the R program below is not giving me the sums I expect to see, viz., 382+170=552 4730+170=4900 5+6=11 199+25=224 ################################################### #full R program: mydata <- data.frame(covid=c(0,0,0,0,1,1,1,1), sex=(rep(c(1,1,0,0),2)), status=rep(c(1,0),2), values=c(382,4730,5,199,170,497,6,25)) mydata by(mydata,list(mydata\$sex,mydata\$status),sum) by(mydata,list(mydata\$sex,mydata\$status),print) ################################################### More complete explanation of my question   I have created a simple dataframe having three factors:  mydata <- data.frame(covid=c(0,0,0,0,1,1,1,1),  sex=(rep(c(1,1,0,0),2)),  status=rep(c(1,0),2),  values=c(382,4730,5,199,170,497,6,25))    > mydata   covid sex status values 1     0   1      1    382 2     0   1      0   4730 3     0   0      1      5 4     0   0      0    199 5     1   1      1    170 6     1   1      0    497 7     1   0      1      6 8     1   0      0     25   When I use the by function with a sum as an argument, I don’t get the sums that I would expect to receive based either on the listing of the dataframe above, or from using by with print as an argument:   > by(mydata,list(mydata\$sex,mydata\$status),sum) : 0 : 0 [1] 225 ------------------------------------------------------------------------------- : 1 : 0 [1] 5230 ------------------------------------------------------------------------------- : 0 : 1 [1] 14 ------------------------------------------------------------------------------- : 1 : 1 [1] 557   I expected to see the following sums: 382+170=552 4730+170=4900 5+6=11 199+25=224 Which as can be seen by the output above, I am not getting.   Using print as an argument to the by function, I get the values grouped as I would expect, but for some reason I get a double printing of the values!   > by(mydata,list(mydata\$sex,mydata\$status),print)   covid sex status values 4     0   0      0    199 8     1   0      0     25   covid sex status values 2     0   1      0   4730 6     1   1      0    497   covid sex status values 3     0   0      1      5 7     1   0      1      6   covid sex status values 1     0   1      1    382 5     1   1      1    170 : 0 : 0   covid sex status values 4     0   0      0    199 8     1   0      0     25 ------------------------------------------------------------------------------- : 1 : 0   covid sex status values 2     0   1      0   4730 6     1   1      0    497 ------------------------------------------------------------------------------- : 0 : 1   covid sex status values 3     0   0      1      5 7     1   0      1      6 ------------------------------------------------------------------------------- : 1 : 1   covid sex status values 1     0   1      1    382 5     1   1      1    170   What am I doing wrong, or what don’t I understand About the by function?   Thank you John     John David Sorkin M.D., Ph.D. Professor of Medicine Chief, Biostatistics and Informatics University of Maryland School of Medicine Division of Gerontology and Geriatric Medicine Baltimore VA Medical Center 10 North Greene Street GRECC (BT/18/GR) Baltimore, MD 21201-1524 (Phone) 410-605-7119 (Fax) 410-605-7913 (Please call phone number above prior to faxing) ______________________________________________ [hidden email] mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.
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## Re: by function with sum does not give what is expected from by function with print

 by() chooses **data frame** subsets -- sum() is acting on these frames, adding up everything in them. Try this instead: > by(mydata,list(mydata\$sex,mydata\$status),function(x)sum(x\$values)) : 0 : 0 [1] 224 ----------------------------------------------------------- : 1 : 0 [1] 5227 ----------------------------------------------------------- : 0 : 1 [1] 11 ----------------------------------------------------------- : 1 : 1 [1] 552 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 Thu, Jul 23, 2020 at 3:25 PM Sorkin, John <[hidden email]> wrote: > Colleagues, > > The by function in the R program below is not giving me the sums > I expect to see, viz., > 382+170=552 > 4730+170=4900 > 5+6=11 > 199+25=224 > ################################################### > #full R program: > mydata <- data.frame(covid=c(0,0,0,0,1,1,1,1), > sex=(rep(c(1,1,0,0),2)), > status=rep(c(1,0),2), > values=c(382,4730,5,199,170,497,6,25)) > mydata > by(mydata,list(mydata\$sex,mydata\$status),sum) > by(mydata,list(mydata\$sex,mydata\$status),print) > ################################################### > > More complete explanation of my question > > I have created a simple dataframe having three factors: >  mydata <- data.frame(covid=c(0,0,0,0,1,1,1,1), >  sex=(rep(c(1,1,0,0),2)), >  status=rep(c(1,0),2), >  values=c(382,4730,5,199,170,497,6,25)) > >  > mydata >   covid sex status values > 1     0   1      1    382 > 2     0   1      0   4730 > 3     0   0      1      5 > 4     0   0      0    199 > 5     1   1      1    170 > 6     1   1      0    497 > 7     1   0      1      6 > 8     1   0      0     25 > > When I use the by function with a sum as an argument, I don’t > get the sums that I would expect to > receive based either on the listing of the dataframe above, > or from using by with print as an argument: > > > by(mydata,list(mydata\$sex,mydata\$status),sum) > : 0 > : 0 > [1] 225 > ------------------------------------------------------------------------------- > > : 1 > : 0 > [1] 5230 > ------------------------------------------------------------------------------- > > : 0 > : 1 > [1] 14 > ------------------------------------------------------------------------------- > > : 1 > : 1 > [1] 557 > > I expected to see the following sums: > 382+170=552 > 4730+170=4900 > 5+6=11 > 199+25=224 > Which as can be seen by the output above, I am not getting. > > Using print as an argument to the by function, I get the values > grouped as I would expect, but for some reason I get a double > printing of the values! > > > by(mydata,list(mydata\$sex,mydata\$status),print) >   covid sex status values > 4     0   0      0    199 > 8     1   0      0     25 >   covid sex status values > 2     0   1      0   4730 > 6     1   1      0    497 >   covid sex status values > 3     0   0      1      5 > 7     1   0      1      6 >   covid sex status values > 1     0   1      1    382 > 5     1   1      1    170 > : 0 > : 0 >   covid sex status values > 4     0   0      0    199 > 8     1   0      0     25 > ------------------------------------------------------------------------------- > > : 1 > : 0 >   covid sex status values > 2     0   1      0   4730 > 6     1   1      0    497 > ------------------------------------------------------------------------------- > > : 0 > : 1 >   covid sex status values > 3     0   0      1      5 > 7     1   0      1      6 > ------------------------------------------------------------------------------- > > : 1 > : 1 >   covid sex status values > 1     0   1      1    382 > 5     1   1      1    170 > > What am I doing wrong, or what don’t I understand > About the by function? > > Thank you > John > > > > > > > > > > > > > > > > > > > > John David Sorkin M.D., Ph.D. > > Professor of Medicine > > Chief, Biostatistics and Informatics > > University of Maryland School of Medicine Division of Gerontology and > Geriatric Medicine > > Baltimore VA Medical Center > > 10 North Greene Street > > GRECC (BT/18/GR) > > Baltimore, MD 21201-1524 > > (Phone) 410-605-7119 > > (Fax) 410-605-7913 (Please call phone number above prior to faxing) > > > > ______________________________________________ > [hidden email] 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. >         [[alternative HTML version deleted]] ______________________________________________ [hidden email] mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.
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## Re: by function with sum does not give what is expected from by function with print

 In reply to this post by Sorkin, John On 23/07/2020 6:15 p.m., Sorkin, John wrote: > Colleagues, >   > The by function in the R program below is not giving me the sums > I expect to see, viz., > 382+170=552 > 4730+170=4900 > 5+6=11 > 199+25=224 > ################################################### > #full R program: > mydata <- data.frame(covid=c(0,0,0,0,1,1,1,1), > sex=(rep(c(1,1,0,0),2)), > status=rep(c(1,0),2), > values=c(382,4730,5,199,170,497,6,25)) > mydata > by(mydata,list(mydata\$sex,mydata\$status),sum) > by(mydata,list(mydata\$sex,mydata\$status),print) > ################################################### The problem is that you are summing the mydata values, not the mydata\$values values.  That will include covid, sex and status in the sums.  I think you'll get what you should (though it doesn't match what you say you expected, which looks wrong to me) with this code: by(mydata\$values,list(mydata\$sex,mydata\$status),sum) for 0,0, the sum is 224 = 199+25 for 0,1, the sum is  11 = 5+6 for 1,0, the sum is 5227 = 4730 + 497 (not 4730 + 170) for 1,1, the sum is 552 = 382 + 170 Duncan Murdoch > > More complete explanation of my question >   > I have created a simple dataframe having three factors: >   mydata <- data.frame(covid=c(0,0,0,0,1,1,1,1), >   sex=(rep(c(1,1,0,0),2)), >   status=rep(c(1,0),2), >   values=c(382,4730,5,199,170,497,6,25)) >   >   > mydata >    covid sex status values > 1     0   1      1    382 > 2     0   1      0   4730 > 3     0   0      1      5 > 4     0   0      0    199 > 5     1   1      1    170 > 6     1   1      0    497 > 7     1   0      1      6 > 8     1   0      0     25 >   > When I use the by function with a sum as an argument, I don’t > get the sums that I would expect to > receive based either on the listing of the dataframe above, > or from using by with print as an argument: >   >> by(mydata,list(mydata\$sex,mydata\$status),sum) > : 0 > : 0 > [1] 225 > ------------------------------------------------------------------------------- > : 1 > : 0 > [1] 5230 > ------------------------------------------------------------------------------- > : 0 > : 1 > [1] 14 > ------------------------------------------------------------------------------- > : 1 > : 1 > [1] 557 >   > I expected to see the following sums: > 382+170=552 > 4730+170=4900 > 5+6=11 > 199+25=224 > Which as can be seen by the output above, I am not getting. >   > Using print as an argument to the by function, I get the values > grouped as I would expect, but for some reason I get a double > printing of the values! >   >> by(mydata,list(mydata\$sex,mydata\$status),print) >    covid sex status values > 4     0   0      0    199 > 8     1   0      0     25 >    covid sex status values > 2     0   1      0   4730 > 6     1   1      0    497 >    covid sex status values > 3     0   0      1      5 > 7     1   0      1      6 >    covid sex status values > 1     0   1      1    382 > 5     1   1      1    170 > : 0 > : 0 >    covid sex status values > 4     0   0      0    199 > 8     1   0      0     25 > ------------------------------------------------------------------------------- > : 1 > : 0 >    covid sex status values > 2     0   1      0   4730 > 6     1   1      0    497 > ------------------------------------------------------------------------------- > : 0 > : 1 >    covid sex status values > 3     0   0      1      5 > 7     1   0      1      6 > ------------------------------------------------------------------------------- > : 1 > : 1 >    covid sex status values > 1     0   1      1    382 > 5     1   1      1    170 >   > What am I doing wrong, or what don’t I understand > About the by function? >   > Thank you > John >   >   > > > > > > > > > > > > > > > > > > John David Sorkin M.D., Ph.D. > > Professor of Medicine > > Chief, Biostatistics and Informatics > > University of Maryland School of Medicine Division of Gerontology and Geriatric Medicine > > Baltimore VA Medical Center > > 10 North Greene Street > > GRECC (BT/18/GR) > > Baltimore, MD 21201-1524 > > (Phone) 410-605-7119 > > (Fax) 410-605-7913 (Please call phone number above prior to faxing) > > > > ______________________________________________ > [hidden email] 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. > ______________________________________________ [hidden email] mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.
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## Re: by function with sum does not give what is expected from by function with print

 On 2020-07-23 18:54 -0400, Duncan Murdoch wrote: > On 23/07/2020 6:15 p.m., Sorkin, John wrote: > > Colleagues, > > The by function in the R program below is not giving me the sums > > I expect to see, viz., > > 382+170=552 > > 4730+170=4900 > > 5+6=11 > > 199+25=224 > > ################################################### > > #full R program: > > mydata <- data.frame(covid=c(0,0,0,0,1,1,1,1), > > sex=(rep(c(1,1,0,0),2)), > > status=rep(c(1,0),2), > > values=c(382,4730,5,199,170,497,6,25)) > > mydata > > by(mydata,list(mydata\$sex,mydata\$status),sum) > > by(mydata,list(mydata\$sex,mydata\$status),print) > > ################################################### > > The problem is that you are summing the mydata values, not the mydata\$values > values.  That will include covid, sex and status in the sums.  I think > you'll get what you should (though it doesn't match what you say you > expected, which looks wrong to me) with this code: > > by(mydata\$values,list(mydata\$sex,mydata\$status),sum) > > for 0,0, the sum is 224 = 199+25 > for 0,1, the sum is  11 = 5+6 > for 1,0, the sum is 5227 = 4730 + 497 (not 4730 + 170) > for 1,1, the sum is 552 = 382 + 170 Dear John, Aggregate also does this, but sex and status are columns in a data.frame and not attributes of the double.         aggregate(x=list("values"=mydata\$values),                   by=list("sex"=mydata\$sex,                           "status"=mydata\$status),                   FUN=sum) yields           sex status values         1   0      0    224         2   1      0   5227         3   0      1     11         4   1      1    552 Best, Rasmus ______________________________________________ [hidden email] mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code. signature.asc (849 bytes) Download Attachment