Bendix Carstensen
2019-Apr-25 11:59 UTC
[R] xtabs ignores l.h.s. rows with NA in just one column - bug or facility?
Here is an example showing that xtabs and cbind are not commutative, which at
least I thought reading the help page for xtabs.
print( sessionInfo(), l=F )
xx <- c( 6,11,38,17)
yy <- c(NA,26,18,48)
ff <- c('a','a','b','b')
data.frame( xx, yy, ff )
xtabs( cbind(xx,yy) ~ ff )
cbind( xtabs(xx ~ ff ),
xtabs(yy ~ ff ) )
Here is the result from my xomputer:
> print( sessionInfo(), l=F )
R version 3.5.3 (2019-03-11)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 14.04.6 LTS
Matrix products: default
BLAS: /usr/lib/openblas-base/libopenblas.so.0
LAPACK: /usr/lib/lapack/liblapack.so.3.0
attached base packages:
[1] utils datasets graphics grDevices stats methods base
loaded via a namespace (and not attached):
[1] compiler_3.5.3> xx <- c( 6,11,38,17)
> yy <- c(NA,26,18,48)
> ff <- c('a','a','b','b')
> data.frame( xx, yy, ff )
xx yy ff
1 6 NA a
2 11 26 a
3 38 18 b
4 17 48 b> xtabs( cbind(xx,yy) ~ ff )
ff xx yy
a 11 26
b 55 66> cbind( xtabs(xx ~ ff ),
+ xtabs(yy ~ ff ) )
[,1] [,2]
a 17 26
b 55 66>
I would have guessed the upper left entry would be 17 in the first instance too,
but it appears that xtabs does something like complete.cases() on the l.h.s.
before summing. At least this should be in the description.
Am I missing something here?
Bendix Carstensen
Steno Diabetes Center Copenhagen
________________________________
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David L Carlson
2019-Apr-25 13:55 UTC
[R] xtabs ignores l.h.s. rows with NA in just one column - bug or facility?
The documentation describes how to control the behavior of missing values:> xtabs( cbind(xx,yy) ~ ff, addNA=TRUE)ff xx yy a 17 b 55 66 But of course, now you do not get 26 in the (a, yy) cell because 26 + NA = NA. ---------------------------------------- David L Carlson Department of Anthropology Texas A&M University College Station, TX 77843-4352 -----Original Message----- From: R-help <r-help-bounces at r-project.org> On Behalf Of Bendix Carstensen Sent: Thursday, April 25, 2019 6:59 AM To: r-help at r-project.org Subject: [R] xtabs ignores l.h.s. rows with NA in just one column - bug or facility? Here is an example showing that xtabs and cbind are not commutative, which at least I thought reading the help page for xtabs. print( sessionInfo(), l=F ) xx <- c( 6,11,38,17) yy <- c(NA,26,18,48) ff <- c('a','a','b','b') data.frame( xx, yy, ff ) xtabs( cbind(xx,yy) ~ ff ) cbind( xtabs(xx ~ ff ), xtabs(yy ~ ff ) ) Here is the result from my xomputer:> print( sessionInfo(), l=F )R version 3.5.3 (2019-03-11) Platform: x86_64-pc-linux-gnu (64-bit) Running under: Ubuntu 14.04.6 LTS Matrix products: default BLAS: /usr/lib/openblas-base/libopenblas.so.0 LAPACK: /usr/lib/lapack/liblapack.so.3.0 attached base packages: [1] utils datasets graphics grDevices stats methods base loaded via a namespace (and not attached): [1] compiler_3.5.3> xx <- c( 6,11,38,17) > yy <- c(NA,26,18,48) > ff <- c('a','a','b','b') > data.frame( xx, yy, ff )xx yy ff 1 6 NA a 2 11 26 a 3 38 18 b 4 17 48 b> xtabs( cbind(xx,yy) ~ ff )ff xx yy a 11 26 b 55 66> cbind( xtabs(xx ~ ff ),+ xtabs(yy ~ ff ) ) [,1] [,2] a 17 26 b 55 66>I would have guessed the upper left entry would be 17 in the first instance too, but it appears that xtabs does something like complete.cases() on the l.h.s. before summing. At least this should be in the description. Am I missing something here? Bendix Carstensen Steno Diabetes Center Copenhagen ________________________________ Denne e-mail indeholder fortrolig information. Hvis du ikke er den rette modtager af denne e-mail eller hvis du modtager den ved en fejltagelse, beder vi dig venligst informere afsender om fejlen ved at bruge svarfunktionen. Samtidig bedes du slette e-mailen med det samme uden at videresende eller kopiere den. ______________________________________________ R-help at 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.
Bendix Carstensen
2019-Apr-25 14:01 UTC
[R] xtabs ignores l.h.s. rows with NA in just one column - bug or facility?
Thanks for that, but the documentation also says that teh default behaviour is to use na.action=na.pass, which normally just ignores missing values, whereas xtabs seems to ignore the entire row... /Bendix ________________________________________ From: David L Carlson <dcarlson at tamu.edu> Sent: 25 April 2019 15:55 To: Bendix Carstensen; r-help at r-project.org Subject: RE: xtabs ignores l.h.s. rows with NA in just one column - bug or facility? The documentation describes how to control the behavior of missing values:> xtabs( cbind(xx,yy) ~ ff, addNA=TRUE)ff xx yy a 17 b 55 66 But of course, now you do not get 26 in the (a, yy) cell because 26 + NA = NA. ---------------------------------------- David L Carlson Department of Anthropology Texas A&M University College Station, TX 77843-4352 -----Original Message----- From: R-help <r-help-bounces at r-project.org> On Behalf Of Bendix Carstensen Sent: Thursday, April 25, 2019 6:59 AM To: r-help at r-project.org Subject: [R] xtabs ignores l.h.s. rows with NA in just one column - bug or facility? Here is an example showing that xtabs and cbind are not commutative, which at least I thought reading the help page for xtabs. print( sessionInfo(), l=F ) xx <- c( 6,11,38,17) yy <- c(NA,26,18,48) ff <- c('a','a','b','b') data.frame( xx, yy, ff ) xtabs( cbind(xx,yy) ~ ff ) cbind( xtabs(xx ~ ff ), xtabs(yy ~ ff ) ) Here is the result from my xomputer:> print( sessionInfo(), l=F )R version 3.5.3 (2019-03-11) Platform: x86_64-pc-linux-gnu (64-bit) Running under: Ubuntu 14.04.6 LTS Matrix products: default BLAS: /usr/lib/openblas-base/libopenblas.so.0 LAPACK: /usr/lib/lapack/liblapack.so.3.0 attached base packages: [1] utils datasets graphics grDevices stats methods base loaded via a namespace (and not attached): [1] compiler_3.5.3> xx <- c( 6,11,38,17) > yy <- c(NA,26,18,48) > ff <- c('a','a','b','b') > data.frame( xx, yy, ff )xx yy ff 1 6 NA a 2 11 26 a 3 38 18 b 4 17 48 b> xtabs( cbind(xx,yy) ~ ff )ff xx yy a 11 26 b 55 66> cbind( xtabs(xx ~ ff ),+ xtabs(yy ~ ff ) ) [,1] [,2] a 17 26 b 55 66>I would have guessed the upper left entry would be 17 in the first instance too, but it appears that xtabs does something like complete.cases() on the l.h.s. before summing. At least this should be in the description. Am I missing something here? Bendix Carstensen Steno Diabetes Center Copenhagen ________________________________ Denne e-mail indeholder fortrolig information. Hvis du ikke er den rette modtager af denne e-mail eller hvis du modtager den ved en fejltagelse, beder vi dig venligst informere afsender om fejlen ved at bruge svarfunktionen. Samtidig bedes du slette e-mailen med det samme uden at videresende eller kopiere den. ______________________________________________ R-help at 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. ________________________________ Denne e-mail indeholder fortrolig information. Hvis du ikke er den rette modtager af denne e-mail eller hvis du modtager den ved en fejltagelse, beder vi dig venligst informere afsender om fejlen ved at bruge svarfunktionen. Samtidig bedes du slette e-mailen med det samme uden at videresende eller kopiere den.