I'm a newbie for R lang. And I recently came across the "Recycling Rule" when adding two vectors of unequal length. I learned from this tutor [ http://www.r-tutor.com/r-introduction/vector/vector-arithmetics ] that: """""" If two vectors are of unequal length, the shorter one will be recycled in order to match the longer vector. For example, the following vectors u and v have different lengths, and their sum is computed by recycling values of the shorter vector u.> u = c(10, 20, 30)> v = c(1, 2, 3, 4, 5, 6, 7, 8, 9)> u + v[1] 11 22 33 14 25 36 17 28 39 """""" And I wondered, why the shorter vecter u should be recycled? Why not just leave the extra values(4,5,6,7,8,9) in the longer vector untouched by default? Otherwise is it better to have another function that could add vectors without recycling? Right now the recycling feature bugs me a lot. Sent with [ProtonMail](https://protonmail.com) Secure Email. [[alternative HTML version deleted]]
Better get over it, because it isn't going to change. To avoid it, always work with vectors of the same length. This is a logical extension of the idea that a scalar adds to every element of a vector. -- Sent from my phone. Please excuse my brevity. On December 12, 2017 9:41:06 PM PST, Maingo via R-help <r-help at r-project.org> wrote:>I'm a newbie for R lang. And I recently came across the "Recycling >Rule" when adding two vectors of unequal length. > >I learned from this tutor [ >http://www.r-tutor.com/r-introduction/vector/vector-arithmetics ] that: > >"""""" > >If two vectors are of unequal length, the shorter one will be recycled >in order to match the longer vector. For example, the following vectors >u and v have different lengths, and their sum is computed by recycling >values of the shorter vector u. > >> u = c(10, 20, 30) > >> v = c(1, 2, 3, 4, 5, 6, 7, 8, 9) > >> u + v > >[1] 11 22 33 14 25 36 17 28 39 > >"""""" > >And I wondered, why the shorter vecter u should be recycled? Why not >just leave the extra values(4,5,6,7,8,9) in the longer vector untouched >by default? > >Otherwise is it better to have another function that could add vectors >without recycling? Right now the recycling feature bugs me a lot. > >Sent with [ProtonMail](https://protonmail.com) Secure Email. > [[alternative HTML version deleted]] > >______________________________________________ >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.
Hi
If some feature does not suit your intentions you can make your own. Especially
in this simple case.
myadd<-function(x,y) {
if(length(x)!=length(y)) {
n <- max(length(x), length(y))
length(x) <- n
length(y) <- n
x[is.na(x)]<-0
y[is.na(u)]<-0
}
x+y
}
> myadd(u,v)
[1] 11 22 33 4 5 6 7 8 9>
But usually data to R are imported as data frames and missing values are set to
NA.
In such case you could use rowSums with na.rm argument.
Cheers
Petr
> -----Original Message-----
> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Maingo
via R-
> help
> Sent: Wednesday, December 13, 2017 6:41 AM
> To: r-help at r-project.org
> Subject: [R] Add vectors of unequal length without recycling?
>
> I'm a newbie for R lang. And I recently came across the "Recycling
Rule" when
> adding two vectors of unequal length.
>
> I learned from this tutor [ http://www.r-tutor.com/r-
> introduction/vector/vector-arithmetics ] that:
>
> """"""
>
> If two vectors are of unequal length, the shorter one will be recycled in
order to
> match the longer vector. For example, the following vectors u and v have
> different lengths, and their sum is computed by recycling values of the
shorter
> vector u.
>
> > u = c(10, 20, 30)
>
> > v = c(1, 2, 3, 4, 5, 6, 7, 8, 9)
>
> > u + v
>
> [1] 11 22 33 14 25 36 17 28 39
>
> """"""
>
> And I wondered, why the shorter vecter u should be recycled? Why not just
> leave the extra values(4,5,6,7,8,9) in the longer vector untouched by
default?
>
> Otherwise is it better to have another function that could add vectors
without
> recycling? Right now the recycling feature bugs me a lot.
>
> Sent with [ProtonMail](https://protonmail.com) Secure Email.
> [[alternative HTML version deleted]]
>
> ______________________________________________
> 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.
________________________________
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Without recycling you would get:
u <- c(10, 20, 30)
u + 1
#[1] 11 20 30
which would be pretty inconvenient.
(Note that the recycling rule has to make a special case for when one
argument has length zero - the output then has length zero as well.)
Bill Dunlap
TIBCO Software
wdunlap tibco.com
On Tue, Dec 12, 2017 at 9:41 PM, Maingo via R-help <r-help at
r-project.org>
wrote:
> I'm a newbie for R lang. And I recently came across the "Recycling
Rule"
> when adding two vectors of unequal length.
>
> I learned from this tutor [ http://www.r-tutor.com/r-
> introduction/vector/vector-arithmetics ] that:
>
> """"""
>
> If two vectors are of unequal length, the shorter one will be recycled in
> order to match the longer vector. For example, the following vectors u and
> v have different lengths, and their sum is computed by recycling values of
> the shorter vector u.
>
> > u = c(10, 20, 30)
>
> > v = c(1, 2, 3, 4, 5, 6, 7, 8, 9)
>
> > u + v
>
> [1] 11 22 33 14 25 36 17 28 39
>
> """"""
>
> And I wondered, why the shorter vecter u should be recycled? Why not just
> leave the extra values(4,5,6,7,8,9) in the longer vector untouched by
> default?
>
> Otherwise is it better to have another function that could add vectors
> without recycling? Right now the recycling feature bugs me a lot.
>
> Sent with [ProtonMail](https://protonmail.com) Secure Email.
> [[alternative HTML version deleted]]
>
> ______________________________________________
> 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.
>
[[alternative HTML version deleted]]
William Michels
2017-Dec-13 18:17 UTC
[R] Add vectors of unequal length without recycling?
Maingo, See previous discussion below on rbind.na() and cbind.na() scripts: https://stat.ethz.ch/pipermail/r-help/2016-December/443790.html You might consider binding first then adding orthogonally. So rbind.na() then colSums(), OR cbind.na() then rowSums(). Best of luck, W Michels, Ph.D. On Wed, Dec 13, 2017 at 8:34 AM, William Dunlap via R-help <r-help at r-project.org> wrote:> Without recycling you would get: > u <- c(10, 20, 30) > u + 1 > #[1] 11 20 30 > which would be pretty inconvenient. > > (Note that the recycling rule has to make a special case for when one > argument has length zero - the output then has length zero as well.) > > > Bill Dunlap > TIBCO Software > wdunlap tibco.com > > On Tue, Dec 12, 2017 at 9:41 PM, Maingo via R-help <r-help at r-project.org> > wrote: > >> I'm a newbie for R lang. And I recently came across the "Recycling Rule" >> when adding two vectors of unequal length. >> >> I learned from this tutor [ http://www.r-tutor.com/r- >> introduction/vector/vector-arithmetics ] that: >> >> """""" >> >> If two vectors are of unequal length, the shorter one will be recycled in >> order to match the longer vector. For example, the following vectors u and >> v have different lengths, and their sum is computed by recycling values of >> the shorter vector u. >> >> > u = c(10, 20, 30) >> >> > v = c(1, 2, 3, 4, 5, 6, 7, 8, 9) >> >> > u + v >> >> [1] 11 22 33 14 25 36 17 28 39 >> >> """""" >> >> And I wondered, why the shorter vecter u should be recycled? Why not just >> leave the extra values(4,5,6,7,8,9) in the longer vector untouched by >> default? >> >> Otherwise is it better to have another function that could add vectors >> without recycling? Right now the recycling feature bugs me a lot. >> >> Sent with [ProtonMail](https://protonmail.com) Secure Email. >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> 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. >> > > [[alternative HTML version deleted]] > > ______________________________________________ > 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.