I have a df with a vector v. For each element of the vector, I want to
know whether the i-2nd element is the same as the ith element. For
example:
given
v=c(A,C,D,C) the result should be:
FALSE,FALSE,FALSE,TRUE.
I attempted something using indexing in a for loop such as (bad,
incorrect example):
for (i in v){
if [i]==[i-2] print T
else print F
}
However, this is obviously wrong.
Can someone provide a nice way to solve this?
Homework?? There is a no homework policy on this list. 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 Sun, Jul 23, 2017 at 11:43 AM, Davide Piffer <pifferdavide at gmail.com> wrote:> I have a df with a vector v. For each element of the vector, I want to > know whether the i-2nd element is the same as the ith element. For > example: > given > v=c(A,C,D,C) the result should be: > FALSE,FALSE,FALSE,TRUE. > > I attempted something using indexing in a for loop such as (bad, > incorrect example): > for (i in v){ > if [i]==[i-2] print T > else print F > } > > However, this is obviously wrong. > Can someone provide a nice way to solve this? > > ______________________________________________ > 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.
No homework. Just a genuine question On 23 July 2017 at 22:00, Bert Gunter <bgunter.4567 at gmail.com> wrote:> Homework?? There is a no homework policy on this list. > > 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 Sun, Jul 23, 2017 at 11:43 AM, Davide Piffer <pifferdavide at gmail.com> wrote: >> I have a df with a vector v. For each element of the vector, I want to >> know whether the i-2nd element is the same as the ith element. For >> example: >> given >> v=c(A,C,D,C) the result should be: >> FALSE,FALSE,FALSE,TRUE. >> >> I attempted something using indexing in a for loop such as (bad, >> incorrect example): >> for (i in v){ >> if [i]==[i-2] print T >> else print F >> } >> >> However, this is obviously wrong. >> Can someone provide a nice way to solve this? >> >> ______________________________________________ >> 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, On 07/23/2017 11:43 AM, Davide Piffer wrote:> I have a df with a vector v. For each element of the vector, I want to > know whether the i-2nd element is the same as the ith element. For > example: > given > v=c(A,C,D,C) the result should be: > FALSE,FALSE,FALSE,TRUE. > > I attempted something using indexing in a for loop such as (bad, > incorrect example): > for (i in v){ > if [i]==[i-2] print T > else print F > } > > However, this is obviously wrong.Why don't you provide code that is actually valid R code so we can run it. Then we can see if it does the right thing or not.> Can someone provide a nice way to solve this?Does this do what you want? isSameAsPrevious <- function(v, k=1) c(rep(FALSE, k), head(v,n=-k) == tail(v, n=-k)) Then: > isSameAsPrevious(v, 2) [1] FALSE FALSE FALSE TRUE H.> > ______________________________________________ > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://urldefense.proofpoint.com/v2/url?u=https-3A__stat.ethz.ch_mailman_listinfo_r-2Dhelp&d=DwICAg&c=eRAMFD45gAfqt84VtBcfhQ&r=BK7q3XeAvimeWdGbWY_wJYbW0WYiZvSXAJJKaaPhzWA&m=YfPp2NbGMLV4frEpzG4QQFssqMnld91RlQHDdWcvFtw&s=-KVWCgOZsuCGKiZ7aXq4jhZBw97MrEzg19X8yFD60l8&e> PLEASE do read the posting guide https://urldefense.proofpoint.com/v2/url?u=http-3A__www.R-2Dproject.org_posting-2Dguide.html&d=DwICAg&c=eRAMFD45gAfqt84VtBcfhQ&r=BK7q3XeAvimeWdGbWY_wJYbW0WYiZvSXAJJKaaPhzWA&m=YfPp2NbGMLV4frEpzG4QQFssqMnld91RlQHDdWcvFtw&s=HGLgncA6cBilW_DkIzjBEizqo1AmvlshmOHQr4td1vc&e> and provide commented, minimal, self-contained, reproducible code. >-- Herv? Pag?s Program in Computational Biology Division of Public Health Sciences Fred Hutchinson Cancer Research Center 1100 Fairview Ave. N, M1-B514 P.O. Box 19024 Seattle, WA 98109-1024 E-mail: hpages at fredhutch.org Phone: (206) 667-5791 Fax: (206) 667-1319
Thanks a lot, Herve'. This worked! On 23 July 2017 at 22:19, Herv? Pag?s <hpages at fredhutch.org> wrote:> Hi, > > On 07/23/2017 11:43 AM, Davide Piffer wrote: >> >> I have a df with a vector v. For each element of the vector, I want to >> know whether the i-2nd element is the same as the ith element. For >> example: >> given >> v=c(A,C,D,C) the result should be: >> FALSE,FALSE,FALSE,TRUE. >> >> I attempted something using indexing in a for loop such as (bad, >> incorrect example): >> for (i in v){ >> if [i]==[i-2] print T >> else print F >> } >> >> However, this is obviously wrong. > > > Why don't you provide code that is actually valid R code so we > can run it. Then we can see if it does the right thing or not. > >> Can someone provide a nice way to solve this? > > > Does this do what you want? > > isSameAsPrevious <- function(v, k=1) c(rep(FALSE, k), head(v,n=-k) => tail(v, n=-k)) > > Then: > >> isSameAsPrevious(v, 2) > [1] FALSE FALSE FALSE TRUE > > H. > > >> >> ______________________________________________ >> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see >> >> https://urldefense.proofpoint.com/v2/url?u=https-3A__stat.ethz.ch_mailman_listinfo_r-2Dhelp&d=DwICAg&c=eRAMFD45gAfqt84VtBcfhQ&r=BK7q3XeAvimeWdGbWY_wJYbW0WYiZvSXAJJKaaPhzWA&m=YfPp2NbGMLV4frEpzG4QQFssqMnld91RlQHDdWcvFtw&s=-KVWCgOZsuCGKiZ7aXq4jhZBw97MrEzg19X8yFD60l8&e>> PLEASE do read the posting guide >> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.R-2Dproject.org_posting-2Dguide.html&d=DwICAg&c=eRAMFD45gAfqt84VtBcfhQ&r=BK7q3XeAvimeWdGbWY_wJYbW0WYiZvSXAJJKaaPhzWA&m=YfPp2NbGMLV4frEpzG4QQFssqMnld91RlQHDdWcvFtw&s=HGLgncA6cBilW_DkIzjBEizqo1AmvlshmOHQr4td1vc&e>> and provide commented, minimal, self-contained, reproducible code. >> > > -- > Herv? Pag?s > > Program in Computational Biology > Division of Public Health Sciences > Fred Hutchinson Cancer Research Center > 1100 Fairview Ave. N, M1-B514 > P.O. Box 19024 > Seattle, WA 98109-1024 > > E-mail: hpages at fredhutch.org > Phone: (206) 667-5791 > Fax: (206) 667-1319