Duncan Murdoch
2015-Feb-15 15:54 UTC
[R] Noob question re: writing while loops on one line
On 15/02/2015 10:08 AM, Sun Shine wrote:> Thanks John: understanding it as a line return makes sense!But it's not right. This is one statement, and it returns the value 3: 1 + 2 This is an error: 1 + ; 2 The semicolon is a statement separator, not a line return. Duncan Murdoch> > Cheers > > Sun > > > On 15/02/15 14:59, John Kane wrote: >> Hi Sun, >> Can you check the code in the one line command in RStudio? >> >> I tied it and got the expected error. Or to put it another way, it should not have run for you :) >> >> The semi-colon is funtioning as a line return >> >> John Kane >> Kingston ON Canada >> >> >>> -----Original Message----- >>> From: phaedrusv at gmail.com >>> Sent: Sun, 15 Feb 2015 10:55:28 +0000 >>> To: drjimlemon at gmail.com >>> Subject: Re: [R] Noob question re: writing while loops on one line >>> >>> Brilliant Jim - that does the trick!! >>> >>> I guess then that the semi-colon rule works for any program or function >>> that is being written on one line? >>> >>> Any reason why when writing this out in the RStudio source editor no >>> semi-colon is required, but it is when written in the interactive >>> console? >>> >>> Thanks again >>> >>> Sun >>> >>> >>> On 15/02/15 10:41, Jim Lemon wrote: >>>> Hi Sun, >>>> Try including a semicolon. >>>> >>>> while(count < 10) { print(count); count<-count+1 } >>>> >>>> Jim >>>> >>>> >>>> On Sun, Feb 15, 2015 at 9:20 PM, Sun Shine <phaedrusv at gmail.com> wrote: >>>>> Hi list >>>>> >>>>> I'm working through some exercises and did a while loop which raised an >>>>> issue for me: >>>>> >>>>> I can write out the while loop so: >>>>> >>>>>> count <- 0 >>>>> while(count < 10) { >>>>> print(count) >>>>> count <- count + 1 >>>>> } >>>>> >>>>> And this works fine. >>>>> >>>>> Trying to do the same thing all on one line however gives this error: >>>>> >>>>> "Error: unexpected symbol in "while(count < 10) { print(count) count"" >>>>> >>>>> My question: >>>>> >>>>> How can one write out a while loop all in one line? Is there a symbol >>>>> or >>>>> something that I should be including? >>>>> >>>>> Thanks for any suggestions. >>>>> >>>>> Sun >>>>> >>>>> ______________________________________________ >>>>> 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. >>> ______________________________________________ >>> 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. >> ____________________________________________________________ >> FREE ONLINE PHOTOSHARING - Share your photos online with your friends and family! >> Visit http://www.inbox.com/photosharing to find out more! >> >> >> > > ______________________________________________ > 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. >
On Sun, Feb 15, 2015 at 9:54 AM, Duncan Murdoch <murdoch.duncan at gmail.com> wrote:> On 15/02/2015 10:08 AM, Sun Shine wrote: > > Thanks John: understanding it as a line return makes sense! > > But it's not right. This is one statement, and it returns the value 3: > > 1 + > 2 > > This is an error: > > 1 + ; 2 > > The semicolon is a statement separator, not a line return. >?Technically speaking a semicolon is a statement terminator, not a statement separator. In the case of the R language, that is a "nit". In the case of Pascal, it is a big difference.> > Duncan Murdoch > >?This is one reason why I _always_ use the semi-colon. It is _never_ really wrong to do so. It may be _unnecessary_ in some case. It is also why I always use <- as the assignment operator (well, that and because I like it from my APL background). If there are two ways to express something, and one of them is _always_ correct whereas the other _might not_ be correct in some cases, then I think doing the former is simply "better form". But, then, I'm anal about other things to. And that doesn't apply to interactive use. I don't terminate my interactive statements with a semi-colon all the time. Just most of the time. Of course, I'm a touch typist too and so it is not really much of a problem for me.? -- He's about as useful as a wax frying pan. 10 to the 12th power microphones = 1 Megaphone Maranatha! <>< John McKown [[alternative HTML version deleted]]
Jeff Newmiller
2015-Feb-15 16:39 UTC
[R] Noob question re: writing while loops on one line
Best not to be pedantic, John, unless you are going to be right. Please read
section 10.3.5 in the R Language Definition document. This is R, not C.
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On February 15, 2015 8:20:39 AM PST, John McKown <john.archie.mckown at
gmail.com> wrote:>On Sun, Feb 15, 2015 at 9:54 AM, Duncan Murdoch
><murdoch.duncan at gmail.com>
>wrote:
>
>> On 15/02/2015 10:08 AM, Sun Shine wrote:
>> > Thanks John: understanding it as a line return makes sense!
>>
>> But it's not right. This is one statement, and it returns the
value
>3:
>>
>> 1 +
>> 2
>>
>> This is an error:
>>
>> 1 + ; 2
>>
>> The semicolon is a statement separator, not a line return.
>>
>
>?Technically speaking a semicolon is a statement terminator, not a
>statement separator. In the case of the R language, that is a
"nit". In
>the
>case of Pascal, it is a big difference.
>
>
>>
>> Duncan Murdoch
>>
>>
>?This is one reason why I _always_ use the semi-colon. It is _never_
>really
>wrong to do so. It may be _unnecessary_ in some case. It is also why I
>always use <- as the assignment operator (well, that and because I like
>it
>from my APL background). If there are two ways to express something,
>and
>one of them is _always_ correct whereas the other _might not_ be
>correct in
>some cases, then I think doing the former is simply "better form".
But,
>then, I'm anal about other things to. And that doesn't apply to
>interactive
>use. I don't terminate my interactive statements with a semi-colon all
>the
>time. Just most of the time. Of course, I'm a touch typist too and so
>it is
>not really much of a problem for me.?
>
>
>
>--
>He's about as useful as a wax frying pan.
>
>10 to the 12th power microphones = 1 Megaphone
>
>Maranatha! <><
>John McKown
>
> [[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.
Duncan Murdoch
2015-Feb-15 20:19 UTC
[R] Noob question re: writing while loops on one line
On 15/02/2015 11:20 AM, John McKown wrote:> On Sun, Feb 15, 2015 at 9:54 AM, Duncan Murdoch > <murdoch.duncan at gmail.com <mailto:murdoch.duncan at gmail.com>>wrote: > > On 15/02/2015 10:08 AM, Sun Shine wrote: > > Thanks John: understanding it as a line return makes sense! > > But it's not right. This is one statement, and it returns the value 3: > > 1 + > 2 > > This is an error: > > 1 + ; 2 > > The semicolon is a statement separator, not a line return. > > > ?Technically speaking a semicolon is a statement terminator, not a > statement separator. In the case of the R language, that is a "nit". In > the case of Pascal, it is a big difference. > > > > Duncan Murdoch > > > ?This is one reason why I _always_ use the semi-colon. It is _never_ > really wrong to do so. It may be _unnecessary_ in some case. It is also > why I always use <- as the assignment operator (well, that and because I > like it from my APL background). If there are two ways to express > something, and one of them is _always_ correct whereas the other _might > not_ be correct in some cases, then I think doing the former is simply > "better form". But, then, I'm anal about other things to. And that > doesn't apply to interactive use. I don't terminate my interactive > statements with a semi-colon all the time. Just most of the time. Of > course, I'm a touch typist too and so it is not really much of a problem > for me.?I don't use semicolons unless they are necessary, and I don't like it when my students do. For example, you could be misled by code like this: x = 1; y = 2; verylongname = x + y + 1; If this were C, verylongname would end up with the value 4. If you read it and only see 3 "terminators", you might think R is the same, but it's not. R sees that as 7 different statements: two on the 1st, 2nd and 4th lines (in each case the second statement is empty), and one statement on line 3. So verylongname ends up with the value 3, not 4. Cues to remind you what language you're using are a good thing. That's one reason to use <- (which I always do) instead of =, and not to use unnecessary semicolons. Duncan Murdoch> > > > -- > He's about as useful as a wax frying pan. > > 10 to the 12th power microphones = 1 Megaphone > > Maranatha! <>< > John McKown