From: Henrik Bengtsson <hb_at_stat.berkeley.edu>

Date: Mon, 28 Jul 2008 12:09:49 -0700

R-help_at_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. Received on Mon 28 Jul 2008 - 19:22:03 GMT

Date: Mon, 28 Jul 2008 12:09:49 -0700

Hi.

On Mon, Jul 28, 2008 at 11:21 AM, Ted Harding
<Ted.Harding_at_manchester.ac.uk> wrote:

> On 28-Jul-08 17:52:31, Henrik Bengtsson wrote:

*>> Use '&' for vectors and '&&' for scalars. Ditto applies to the OR
**>> operator(s). /Henrik
**>
**> What's wrong with using "&" for scalars? Surely it gives the
**> correct answer? Maybe it's simply a bit slower, or something?
*

I don't know the details, but help("&&") says: "The operators '!', '&' and '|' are generic functions[...]". So, yes, you pay the unnecessary cost for dispatching, which you want to avoid for such basic operations. Moreover, personally I would consider it good programming practice to use '&&' when you really mean to. I'd rather see if (eventA && eventB) { ... } than if (eventA & eventB) { ... } even if they two objects are scalars. The latter one tells me that the developer might not know what s/he's doing. I don't if 'codeTools' already now picks on the latter, but it is not hard to imagine that it will one day.

My $0.02

Henrik

*>
**> Ted.
**>
*

>> On Mon, Jul 28, 2008 at 10:36 AM, Wade Wall <wade.wall@gmail.com>

*>> wrote:
**>>> Hi all,
**>>>
**>>> I am trying to convert geometric means in a matrix to cover classes.
**>>> My
**>>> values are as such:
**>>>
**>>> perc<-c(0,0.025136418, 0.316227766, 1.414213562,3.16227766,
**>>> 7.071067812,
**>>> 15.8113883, 35.35533906, 61.23724357, 84.40971508, 97.46794345)
**>>> cover<-c(0,1,2,3,4,5,6,7,8,9,10)
**>>>
**>>> This is what I am trying to accomplish
**>>>
**>>> veg_mean[veg_mean>0 && veg_mean < .1] <- 1
**>>> veg_mean[veg_mean>= .1 && veg_mean < 1.0] <- 2
**>>> veg_mean[veg_mean>=1.0 && veg_mean < 2.0] <- 3
**>>> veg_mean[veg_mean>=2.0 && veg_mean < 5.0] <- 4
**>>> veg_mean[veg_mean>= 5.0 && veg_mean < 10.0] <- 5
**>>> veg_mean[veg_mean>= 10.0 && veg_mean < 25] <- 6
**>>> veg_mean[veg_mean>= 25.0 && veg_mean < 50.0] <- 7
**>>> veg_mean[veg_mean>=50.0 && veg_mean < 75.0] <- 8
**>>> veg_mean[veg_mean>= 75.0 && veg_mean < 95.0 ] <- 9
**>>> veg_mean[veg_mean>= 95.0 && veg_mean <= 100] <- 10
**>>> veg_mean[veg_mean> 100] <- NA
**>>>
**>>> where values are assigned based on the geometric means. However, I
**>>> think
**>>> that my syntax for the && operator is wrong and I can't find a
**>>> reference to
**>>> proper syntax. I basically want to "bin" the geometric means.
**>>>
**>>> Any help would be greatly appreciated.
**>>>
**>>> Thanks,
**>>>
**>>> Wade
**>>>
**>>> [[alternative HTML version deleted]]
**>>>
**>>> ______________________________________________
**>>> R-help_at_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_at_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.
**>
**> --------------------------------------------------------------------
**> E-Mail: (Ted Harding) <Ted.Harding_at_manchester.ac.uk>
**> Fax-to-email: +44 (0)870 094 0861
**> Date: 28-Jul-08 Time: 19:21:08
**> ------------------------------ XFMail ------------------------------
**>
**> ______________________________________________
**> R-help_at_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.
**>
*

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