Monica Palaseanu-Lovejoy
2020-Apr-17 19:55 UTC
[R] custom function gives unexpected result - for me
Hi,
I wrote a relatively simple function. If i run the code inside the function
line by line i am getting the result i was expecting, but if i run the
function, i get a different result.
The function:
grr1 <- function(rn) {
r.up <- c()
for (i in 1:rn-1) {
if (i%%2==0) ru <- seq(1,i) else ru <- seq(i,1)
r.up <- c(r.up, ru)
}
return(r.up)
}
So, if rn is 3 for example i would expect to get 1 1 2
grr1(3)
[1] 1 0 1 1 2
If i run it line by line inside the function:
r.up <- c()> r.up
NULL
i=1
if (i%%2==0) ru <- seq(1,i) else ru <- seq(i,1)> ru
[1] 1
r.up <- c(r.up, ru)
r.up
[1] 1
i=2
if (i%%2==0) ru <- seq(1,i) else ru <- seq(i,1)
ru
[1] 1 2
r.up <- c(r.up, ru)> r.up
[1] 1 1 2
So - i am getting the result i am expecting. From where the 1 0 before what
i expect as a result comes from? I am sure i am doing some very basic
error, but it seems i cannot figure it out.
I run R x64 3.2.6. I know it is not the latest version, but it should not
give me unexpected results because of that i would think.
sessionInfo()
R version 3.6.2 (2019-12-12)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 17763)
Matrix products: default
locale:
[1] LC_COLLATE=English_United States.1252
[2] LC_CTYPE=English_United States.1252
[3] LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C
[5] LC_TIME=English_United States.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods base
loaded via a namespace (and not attached):
[1] compiler_3.6.2
Thanks,
Monica
[[alternative HTML version deleted]]
Peter Langfelder
2020-Apr-17 23:05 UTC
[R] custom function gives unexpected result - for me
You need 1:(m-1) in your function. The operator : has precedence over -:> 1:3-1[1] 0 1 2> 1:(3-1)[1] 1 2 Happened to me a few times as well before I remembered. HTH, Peter On Fri, Apr 17, 2020 at 3:50 PM Monica Palaseanu-Lovejoy <monicapalalovejoy at gmail.com> wrote:> > Hi, > > I wrote a relatively simple function. If i run the code inside the function > line by line i am getting the result i was expecting, but if i run the > function, i get a different result. > > The function: > > grr1 <- function(rn) { > r.up <- c() > for (i in 1:rn-1) { > if (i%%2==0) ru <- seq(1,i) else ru <- seq(i,1) > r.up <- c(r.up, ru) > } > return(r.up) > } > > So, if rn is 3 for example i would expect to get 1 1 2 > > grr1(3) > [1] 1 0 1 1 2 > > If i run it line by line inside the function: > r.up <- c() > > r.up > NULL > > i=1 > if (i%%2==0) ru <- seq(1,i) else ru <- seq(i,1) > > ru > [1] 1 > > r.up <- c(r.up, ru) > r.up > [1] 1 > > i=2 > if (i%%2==0) ru <- seq(1,i) else ru <- seq(i,1) > ru > [1] 1 2 > r.up <- c(r.up, ru) > > r.up > [1] 1 1 2 > > So - i am getting the result i am expecting. From where the 1 0 before what > i expect as a result comes from? I am sure i am doing some very basic > error, but it seems i cannot figure it out. > > I run R x64 3.2.6. I know it is not the latest version, but it should not > give me unexpected results because of that i would think. > > sessionInfo() > R version 3.6.2 (2019-12-12) > Platform: x86_64-w64-mingw32/x64 (64-bit) > Running under: Windows 10 x64 (build 17763) > > Matrix products: default > > locale: > [1] LC_COLLATE=English_United States.1252 > [2] LC_CTYPE=English_United States.1252 > [3] LC_MONETARY=English_United States.1252 > [4] LC_NUMERIC=C > [5] LC_TIME=English_United States.1252 > > attached base packages: > [1] stats graphics grDevices utils datasets methods base > > loaded via a namespace (and not attached): > [1] compiler_3.6.2 > > Thanks, > Monica > > [[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.
Rolf Turner
2020-Apr-17 23:26 UTC
[R] [FORGED] custom function gives unexpected result - for me
The answer is very simple: parentheses. (Also think about "operator precedence".) If you assign rn <- 3, then 1:rn-1 is: [1] 0 1 2 The "-" operator is applied *after* the ":" operator. You want 1:(rn-1) which gives [1] 1 2 and the desired result. cheers, Rolf Turner On 18/04/20 7:55 am, Monica Palaseanu-Lovejoy wrote:> Hi, > > I wrote a relatively simple function. If i run the code inside the function > line by line i am getting the result i was expecting, but if i run the > function, i get a different result. > > The function: > > grr1 <- function(rn) { > r.up <- c() > for (i in 1:rn-1) { > if (i%%2==0) ru <- seq(1,i) else ru <- seq(i,1) > r.up <- c(r.up, ru) > } > return(r.up) > } > > So, if rn is 3 for example i would expect to get 1 1 2 > > grr1(3) > [1] 1 0 1 1 2 > > If i run it line by line inside the function: > r.up <- c() >> r.up > NULL > > i=1 > if (i%%2==0) ru <- seq(1,i) else ru <- seq(i,1) >> ru > [1] 1 > > r.up <- c(r.up, ru) > r.up > [1] 1 > > i=2 > if (i%%2==0) ru <- seq(1,i) else ru <- seq(i,1) > ru > [1] 1 2 > r.up <- c(r.up, ru) >> r.up > [1] 1 1 2 > > So - i am getting the result i am expecting. From where the 1 0 before what > i expect as a result comes from? I am sure i am doing some very basic > error, but it seems i cannot figure it out. > > I run R x64 3.2.6. I know it is not the latest version, but it should not > give me unexpected results because of that i would think. > > sessionInfo() > R version 3.6.2 (2019-12-12) > Platform: x86_64-w64-mingw32/x64 (64-bit) > Running under: Windows 10 x64 (build 17763) > > Matrix products: default > > locale: > [1] LC_COLLATE=English_United States.1252 > [2] LC_CTYPE=English_United States.1252 > [3] LC_MONETARY=English_United States.1252 > [4] LC_NUMERIC=C > [5] LC_TIME=English_United States.1252 > > attached base packages: > [1] stats graphics grDevices utils datasets methods base > > loaded via a namespace (and not attached): > [1] compiler_3.6.2 > > Thanks, > Monica
Jeff Newmiller
2020-Apr-18 00:11 UTC
[R] [FORGED] custom function gives unexpected result - for me
A useful help page: ?Syntax On April 17, 2020 4:26:19 PM PDT, Rolf Turner <r.turner at auckland.ac.nz> wrote:> > >The answer is very simple: parentheses. (Also think about "operator >precedence".) If you assign rn <- 3, then 1:rn-1 is: > >[1] 0 1 2 > >The "-" operator is applied *after* the ":" operator. > >You want 1:(rn-1) which gives > >[1] 1 2 > >and the desired result. > >cheers, > >Rolf Turner > >On 18/04/20 7:55 am, Monica Palaseanu-Lovejoy wrote: >> Hi, >> >> I wrote a relatively simple function. If i run the code inside the >function >> line by line i am getting the result i was expecting, but if i run >the >> function, i get a different result. >> >> The function: >> >> grr1 <- function(rn) { >> r.up <- c() >> for (i in 1:rn-1) { >> if (i%%2==0) ru <- seq(1,i) else ru <- seq(i,1) >> r.up <- c(r.up, ru) >> } >> return(r.up) >> } >> >> So, if rn is 3 for example i would expect to get 1 1 2 >> >> grr1(3) >> [1] 1 0 1 1 2 >> >> If i run it line by line inside the function: >> r.up <- c() >>> r.up >> NULL >> >> i=1 >> if (i%%2==0) ru <- seq(1,i) else ru <- seq(i,1) >>> ru >> [1] 1 >> >> r.up <- c(r.up, ru) >> r.up >> [1] 1 >> >> i=2 >> if (i%%2==0) ru <- seq(1,i) else ru <- seq(i,1) >> ru >> [1] 1 2 >> r.up <- c(r.up, ru) >>> r.up >> [1] 1 1 2 >> >> So - i am getting the result i am expecting. From where the 1 0 >before what >> i expect as a result comes from? I am sure i am doing some very basic >> error, but it seems i cannot figure it out. >> >> I run R x64 3.2.6. I know it is not the latest version, but it >should not >> give me unexpected results because of that i would think. >> >> sessionInfo() >> R version 3.6.2 (2019-12-12) >> Platform: x86_64-w64-mingw32/x64 (64-bit) >> Running under: Windows 10 x64 (build 17763) >> >> Matrix products: default >> >> locale: >> [1] LC_COLLATE=English_United States.1252 >> [2] LC_CTYPE=English_United States.1252 >> [3] LC_MONETARY=English_United States.1252 >> [4] LC_NUMERIC=C >> [5] LC_TIME=English_United States.1252 >> >> attached base packages: >> [1] stats graphics grDevices utils datasets methods base >> >> loaded via a namespace (and not attached): >> [1] compiler_3.6.2 >> >> Thanks, >> Monica > >______________________________________________ >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.-- Sent from my phone. Please excuse my brevity.
Monica Palaseanu-Lovejoy
2020-Apr-18 00:49 UTC
[R] custom function gives unexpected result - for me
Hi, I cannot believe I did that. Usually I remember to add parenthesis but this time obviously I didn?t. Thank you all so much for answering so quickly. Thanks, Monica On Fri, Apr 17, 2020 at 7:06 PM Peter Langfelder <peter.langfelder at gmail.com> wrote:> You need 1:(m-1) in your function. The operator : has precedence over -: > > > 1:3-1 > [1] 0 1 2 > > 1:(3-1) > [1] 1 2 > > Happened to me a few times as well before I remembered. > > HTH, > > Peter > > On Fri, Apr 17, 2020 at 3:50 PM Monica Palaseanu-Lovejoy > <monicapalalovejoy at gmail.com> wrote: > > > > Hi, > > > > I wrote a relatively simple function. If i run the code inside the > function > > line by line i am getting the result i was expecting, but if i run the > > function, i get a different result. > > > > The function: > > > > grr1 <- function(rn) { > > r.up <- c() > > for (i in 1:rn-1) { > > if (i%%2==0) ru <- seq(1,i) else ru <- seq(i,1) > > r.up <- c(r.up, ru) > > } > > return(r.up) > > } > > > > So, if rn is 3 for example i would expect to get 1 1 2 > > > > grr1(3) > > [1] 1 0 1 1 2 > > > > If i run it line by line inside the function: > > r.up <- c() > > > r.up > > NULL > > > > i=1 > > if (i%%2==0) ru <- seq(1,i) else ru <- seq(i,1) > > > ru > > [1] 1 > > > > r.up <- c(r.up, ru) > > r.up > > [1] 1 > > > > i=2 > > if (i%%2==0) ru <- seq(1,i) else ru <- seq(i,1) > > ru > > [1] 1 2 > > r.up <- c(r.up, ru) > > > r.up > > [1] 1 1 2 > > > > So - i am getting the result i am expecting. From where the 1 0 before > what > > i expect as a result comes from? I am sure i am doing some very basic > > error, but it seems i cannot figure it out. > > > > I run R x64 3.2.6. I know it is not the latest version, but it should > not > > give me unexpected results because of that i would think. > > > > sessionInfo() > > R version 3.6.2 (2019-12-12) > > Platform: x86_64-w64-mingw32/x64 (64-bit) > > Running under: Windows 10 x64 (build 17763) > > > > Matrix products: default > > > > locale: > > [1] LC_COLLATE=English_United States.1252 > > [2] LC_CTYPE=English_United States.1252 > > [3] LC_MONETARY=English_United States.1252 > > [4] LC_NUMERIC=C > > [5] LC_TIME=English_United States.1252 > > > > attached base packages: > > [1] stats graphics grDevices utils datasets methods base > > > > loaded via a namespace (and not attached): > > [1] compiler_3.6.2 > > > > Thanks, > > Monica > > > > [[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]]