[R] 1 not equal to 1, and rep command

[Daniel Nordlund]

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
> On Behalf Of Benjamin Høyer
> Sent: Monday, September 12, 2011 6:19 AM
> To: r-help at r-project.org
> Cc: tapo at novozymes.com
> Subject: [R] 1 not equal to 1, and rep command
> 
> Hi
> 
> I need to use rep() to get a vector out, but I have spotted something very
> strange.  See the reproducible example below.
> 
> N <- 79
> seg <- 5
> segN <- N / seg   # = 15.8
> 
> d1 <- seg - ( segN - floor(segN) ) * seg
> d1                    # = 1

Not on my machine.

> d1-1
[1] -3.552714e-15

See FAQ 7.31

> 
> rep(2, d1)          # = numeric(0), strange - why doesn't it print one
> d1-1
[1] -3.552714e-15

<<<snip>>>
> 
> 
> Seems like there's some binary maths errors here somewhere.  Very strange
> to
> me.  Anyway, I need to be able to use the result d1 in a rep() command.
> Any
> way to force rep not to be *too* specific in how it reads its "times"
> argument?

Maybe round() will work for you, since you seem to be expecting a whole number.

rep(2, round(d1))



Hope this is helpful.

Dan

Daniel Nordlund
Bothell, WA USA