Re: [R] how to judge a virable is a integer?
It's due to that, 1 is a numeric, 1.2 is a numeric, though it's true. but deeply, when i want to know 1 is an integer, there seems no easy way to get the answer. So, is there anyone happen to know it? First, you are not being as clear as you may think when you say when i want to know 1 is an integer. It isn't. 1L is an integer. 1 is floating point. Do you want to know whether something is _stored as_ integer (eg 2L), whether it is a floating point number with exactly no nonzero digits after the point (eg 2.0), or whether it is something which would normally be expected to be integer if represented to infinite precision but is not exactly represented because of finite machine precision (eg sqrt(2)^2)? Once you've sorted out which of those you want - I think the last of the three - please read the posts you’re replying to. all.equal() was the suggested answer and is likely to be the nearest to a reliable answer you will get. Almost anything else will at least sometimes fail; for example sqrt(4.0) == 2L # [1] TRUE #But sqrt(2)^2 == 2L #[1] FALSE #whereas all.equal(sqrt(2)^2, 2L) #[1] TRUE Thus, all.equal can be used to test for something that would normally be considered an integer within machine precision, for example using nearly.integer - function(x) all.equal(x, round(x)) You may make the comparison closer to a 'within machine precision' comparison by amending the tol argument to all.equal, which is documented on the help page you were referred to. S Ellison *** This email and any attachments are confidential. Any use, copying or disclosure other than by the intended recipient is unauthorised. If you have received this message in error, please notify the sender immediately via +44(0)20 8943 7000 or notify postmas...@lgcgroup.com and delete this message and any copies from your computer and network. LGC Limited. Registered in England 2991879. Registered office: Queens Road, Teddington, Middlesex, TW11 0LY, UK __ R-help@r-project.org mailing list 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.
Re: [R] how to judge a virable is a integer?
3. all.equal(a, as.integer(a)) Closer, but be aware that all.equal will not always return TRUE or FALSE and - more importantly - as.integer truncates towards zero and does NOT generally round to the nearest integer. a - 4 - sqrt(2)^2 #Analytically 2 all.equal(a, as.integer(a)) # [1] Mean relative difference: 0.5 #because as.integer(a) # [1] 1 To return FALSE from all.equal, wrap it in something like if(all.equal(a, round(a))==TRUE) TRUE else FALSE S *** This email and any attachments are confidential. Any use, copying or disclosure other than by the intended recipient is unauthorised. If you have received this message in error, please notify the sender immediately via +44(0)20 8943 7000 or notify postmas...@lgcgroup.com and delete this message and any copies from your computer and network. LGC Limited. Registered in England 2991879. Registered office: Queens Road, Teddington, Middlesex, TW11 0LY, UK __ R-help@r-project.org mailing list 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] how to judge a virable is a integer?
Dear usRers, I want to judge virable is or not a integer? e.g. is.integer(1) FALSE because it is a numeric, but i want it's true. as.integer may not be used. because i don't know a is 1 or 1.1. -- PO SU mail: desolato...@163.com Majored in Statistics from SJTU __ R-help@r-project.org mailing list 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.
Re: [R] how to judge a virable is a integer?
On 18-10-2014, at 12:41, PO SU rhelpmaill...@163.com wrote: Dear usRers, I want to judge virable is or not a integer? e.g. is.integer(1) FALSE because it is a numeric, but i want it's true. as.integer may not be used. because i don't know a is 1 or 1.1. is.integer is surely what you need if you wish to test if a variable is integer. See this # a - 1 # b - 1L # is.integer(a) [1] FALSE # is.integer(b) [1] TRUE See the help for is.integer to see how you can test for a wholenumber, which might be what you want. Berend __ R-help@r-project.org mailing list 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.
Re: [R] how to judge a virable is a integer?
But i use a-10/b , b is some value ,may be 5, maybe 5.5 not in the form xxL ,so how can i do in the situation to judge a ? -- PO SU mail: desolato...@163.com Majored in Statistics from SJTU At 2014-10-18 18:58:48, Berend Hasselman b...@xs4all.nl wrote: On 18-10-2014, at 12:41, PO SU rhelpmaill...@163.com wrote: Dear usRers, I want to judge virable is or not a integer? e.g. is.integer(1) FALSE because it is a numeric, but i want it's true. as.integer may not be used. because i don't know a is 1 or 1.1. is.integer is surely what you need if you wish to test if a variable is integer. See this # a - 1 # b - 1L # is.integer(a) [1] FALSE # is.integer(b) [1] TRUE See the help for is.integer to see how you can test for a wholenumber, which might be what you want. Berend __ R-help@r-project.org mailing list 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.
Re: [R] how to judge a virable is a integer?
But i use a-10/b , b is some value ,may be 5, maybe 5.5
If you do floating point arithmetic on integers you'll usually get floating
point answers, including the 5.0.
See FAQ 7.31 for the usual floating point problem, and ?all.equal for the usual
answer to it. You could see if a result is close to an integer by,for example,
using all.equal to compare it to itself after rounding.
S
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Re: [R] how to judge a virable is a integer?
It's due to that, 1 is a numeric, 1.2 is a numeric, though it's true. but deeply, when i want to know 1 is an integer, there seems no easy way to get the answer. So, is there anyone happen to know it? -- PO SU mail: desolato...@163.com Majored in Statistics from SJTU At 2014-10-18 20:10:09, S Ellison s.elli...@lgcgroup.com wrote: But i use a-10/b , b is some value ,may be 5, maybe 5.5 If you do floating point arithmetic on integers you'll usually get floating point answers, including the 5.0. See FAQ 7.31 for the usual floating point problem, and ?all.equal for the usual answer to it. You could see if a result is close to an integer by,for example, using all.equal to compare it to itself after rounding. S *** This email and any attachments are confidential. Any use, copying or disclosure other than by the intended recipient is unauthorised. If you have received this message in error, please notify the sender immediately via +44(0)20 8943 7000 or notify postmas...@lgcgroup.com and delete this message and any copies from your computer and network. LGC Limited. Registered in England 2991879. Registered office: Queens Road, Teddington, Middlesex, TW11 0LY, UK __ R-help@r-project.org mailing list 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.
Re: [R] how to judge a virable is a integer?
Don't know if this trivial reply will be useful a=5 is.numeric(a) [1] TRUE b=try is.numeric(b) [1] FALSE Il 18/ott/2014 16:29 PO SU rhelpmaill...@163.com ha scritto: It's due to that, 1 is a numeric, 1.2 is a numeric, though it's true. but deeply, when i want to know 1 is an integer, there seems no easy way to get the answer. So, is there anyone happen to know it? -- PO SU mail: desolato...@163.com Majored in Statistics from SJTU At 2014-10-18 20:10:09, S Ellison s.elli...@lgcgroup.com wrote: But i use a-10/b , b is some value ,may be 5, maybe 5.5 If you do floating point arithmetic on integers you'll usually get floating point answers, including the 5.0. See FAQ 7.31 for the usual floating point problem, and ?all.equal for the usual answer to it. You could see if a result is close to an integer by,for example, using all.equal to compare it to itself after rounding. S *** This email and any attachments are confidential. Any use, copying or disclosure other than by the intended recipient is unauthorised. If you have received this message in error, please notify the sender immediately via +44(0)20 8943 7000 or notify postmas...@lgcgroup.com and delete this message and any copies from your computer and network. LGC Limited. Registered in England 2991879. Registered office: Queens Road, Teddington, Middlesex, TW11 0LY, UK __ R-help@r-project.org mailing list 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@r-project.org mailing list 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.
Re: [R] how to judge a virable is a integer?
Sorry for my previous hurry misunderstanding. Try this link: http://stackoverflow.com/questions/3476782/how-to-check-if-the-number-is-integer 2014-10-18 16:25 GMT+02:00 PO SU rhelpmaill...@163.com: It's due to that, 1 is a numeric, 1.2 is a numeric, though it's true. but deeply, when i want to know 1 is an integer, there seems no easy way to get the answer. So, is there anyone happen to know it? -- PO SU mail: desolato...@163.com Majored in Statistics from SJTU At 2014-10-18 20:10:09, S Ellison s.elli...@lgcgroup.com wrote: But i use a-10/b , b is some value ,may be 5, maybe 5.5 If you do floating point arithmetic on integers you'll usually get floating point answers, including the 5.0. See FAQ 7.31 for the usual floating point problem, and ?all.equal for the usual answer to it. You could see if a result is close to an integer by,for example, using all.equal to compare it to itself after rounding. S *** This email and any attachments are confidential. Any use, copying or disclosure other than by the intended recipient is unauthorised. If you have received this message in error, please notify the sender immediately via +44(0)20 8943 7000 or notify postmas...@lgcgroup.com and delete this message and any copies from your computer and network. LGC Limited. Registered in England 2991879. Registered office: Queens Road, Teddington, Middlesex, TW11 0LY, UK __ R-help@r-project.org mailing list 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@r-project.org mailing list 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.
Re: [R] how to judge a virable is a integer?
Further and last trial: a=5.102 a-floor(a)==0[1] FALSE a=5.9 a-floor(a)==0[1] FALSE a=19 a-floor(a)==0[1] TRUE All the best, Sergio 2014-10-18 16:25 GMT+02:00 PO SU rhelpmaill...@163.com: It's due to that, 1 is a numeric, 1.2 is a numeric, though it's true. but deeply, when i want to know 1 is an integer, there seems no easy way to get the answer. So, is there anyone happen to know it? -- PO SU mail: desolato...@163.com Majored in Statistics from SJTU At 2014-10-18 20:10:09, S Ellison s.elli...@lgcgroup.com wrote: But i use a-10/b , b is some value ,may be 5, maybe 5.5 If you do floating point arithmetic on integers you'll usually get floating point answers, including the 5.0. See FAQ 7.31 for the usual floating point problem, and ?all.equal for the usual answer to it. You could see if a result is close to an integer by,for example, using all.equal to compare it to itself after rounding. S *** This email and any attachments are confidential. Any use, copying or disclosure other than by the intended recipient is unauthorised. If you have received this message in error, please notify the sender immediately via +44(0)20 8943 7000 or notify postmas...@lgcgroup.com and delete this message and any copies from your computer and network. LGC Limited. Registered in England 2991879. Registered office: Queens Road, Teddington, Middlesex, TW11 0LY, UK __ R-help@r-project.org mailing list 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@r-project.org mailing list 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.
Re: [R] how to judge a virable is a integer?
It sounds like you want an 'is.integral' function to tell if a number acts like a mathematical integer, as opposed to 'is.integer', which tells if a number is stored as a 32-bit computer integer. The test will depend on what properties of mathematical integers you are most interested in. is.integral - function (x) (floor(x) == x) (abs(x) + 1 abs(x)) will return TRUE if x has no fractional part and the number's putative successor (predecessor if negative) is different than the number. That latter test is equivalent (roughly) to log2(abs(x))53 and comes into play when you run out of bits in the mantissa of a double precision number. (One might want it to return NA in that case, but I think FALSE works better.) Bill Dunlap TIBCO Software wdunlap tibco.com On Sat, Oct 18, 2014 at 3:41 AM, PO SU rhelpmaill...@163.com wrote: Dear usRers, I want to judge virable is or not a integer? e.g. is.integer(1) FALSE because it is a numeric, but i want it's true. as.integer may not be used. because i don't know a is 1 or 1.1. -- PO SU mail: desolato...@163.com Majored in Statistics from SJTU __ R-help@r-project.org mailing list 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@r-project.org mailing list 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.
Re: [R] how to judge a virable is a integer?
Tks for your help, after investigate in your link, i find there seems three ways can be adoped: 1. is.wholenumber - function(x, tol = .Machine$double.eps^0.5) abs(x - round(x)) tol) e.g. is.wholenumber(1) 2. x%%1==0 3. all.equal(a, as.integer(a)) and also included your last suggestion using floor. and also tks for other helpers！ -- PO SU mail: desolato...@163.com Majored in Statistics from SJTU At 2014-10-18 22:48:15, Sergio Fonda sergio.fond...@gmail.com wrote: Sorry for my previous hurry misunderstanding. Try this link: http://stackoverflow.com/questions/3476782/how-to-check-if-the-number-is-integer 2014-10-18 16:25 GMT+02:00 PO SU rhelpmaill...@163.com: It's due to that, 1 is a numeric, 1.2 is a numeric, though it's true. but deeply, when i want to know 1 is an integer, there seems no easy way to get the answer. So, is there anyone happen to know it? -- PO SU mail: desolato...@163.com Majored in Statistics from SJTU At 2014-10-18 20:10:09, S Ellison s.elli...@lgcgroup.com wrote: But i use a-10/b , b is some value ,may be 5, maybe 5.5 If you do floating point arithmetic on integers you'll usually get floating point answers, including the 5.0. See FAQ 7.31 for the usual floating point problem, and ?all.equal for the usual answer to it. You could see if a result is close to an integer by,for example, using all.equal to compare it to itself after rounding. S *** This email and any attachments are confidential. Any use, copying or disclosure other than by the intended recipient is unauthorised. If you have received this message in error, please notify the sender immediately via +44(0)20 8943 7000 or notify postmas...@lgcgroup.com and delete this message and any copies from your computer and network. LGC Limited. Registered in England 2991879. Registered office: Queens Road, Teddington, Middlesex, TW11 0LY, UK __ R-help@r-project.org mailing list 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@r-project.org mailing list 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.
Re: [R] how to judge a virable is a integer?
3. all.equal(a, as.integer(a)) Note that this one tests if 'a' can be stored accurately as a 32-bit signed integer. If you want to know if 'a' can be used as an accurate count, then you want to test if a+1a (use abs() in case a is negative). E.g., try this for a-2^49-1, about 5*10^14. You have to decide what properties of integers you are interested in. Bill Dunlap TIBCO Software wdunlap tibco.com On Sat, Oct 18, 2014 at 10:02 AM, PO SU rhelpmaill...@163.com wrote: Tks for your help, after investigate in your link, i find there seems three ways can be adoped: 1.is.wholenumber - function(x, tol = .Machine$double.eps^0.5) abs(x - round(x)) tol) e.g. is.wholenumber(1) 2. x%%1==0 3. all.equal(a, as.integer(a)) and also included your last suggestion using floor. and also tks for other helpers！ -- PO SU mail: desolato...@163.com Majored in Statistics from SJTU At 2014-10-18 22:48:15, Sergio Fonda sergio.fond...@gmail.com wrote: Sorry for my previous hurry misunderstanding. Try this link: http://stackoverflow.com/questions/3476782/how-to-check-if-the-number-is-integer 2014-10-18 16:25 GMT+02:00 PO SU rhelpmaill...@163.com: It's due to that, 1 is a numeric, 1.2 is a numeric, though it's true. but deeply, when i want to know 1 is an integer, there seems no easy way to get the answer. So, is there anyone happen to know it? -- PO SU mail: desolato...@163.com Majored in Statistics from SJTU At 2014-10-18 20:10:09, S Ellison s.elli...@lgcgroup.com wrote: But i use a-10/b , b is some value ,may be 5, maybe 5.5 If you do floating point arithmetic on integers you'll usually get floating point answers, including the 5.0. See FAQ 7.31 for the usual floating point problem, and ?all.equal for the usual answer to it. You could see if a result is close to an integer by,for example, using all.equal to compare it to itself after rounding. S *** This email and any attachments are confidential. Any use, copying or disclosure other than by the intended recipient is unauthorised. If you have received this message in error, please notify the sender immediately via +44(0)20 8943 7000 or notify postmas...@lgcgroup.com and delete this message and any copies from your computer and network. LGC Limited. Registered in England 2991879. Registered office: Queens Road, Teddington, Middlesex, TW11 0LY, UK __ R-help@r-project.org mailing list 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@r-project.org mailing list 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@r-project.org mailing list 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.
