# [R] Including a vector element in an if statement

jim holtman jholtman at gmail.com
Mon Apr 20 02:10:05 CEST 2009

```If all you want is a count, then you can construct a logical vector
and count the TRUEs:

sum(a9 < (mean(a9) / 2))

On Sun, Apr 19, 2009 at 5:58 PM, Enda Hargaden <endahargaden at gmail.com> wrote:
> Hi all,
>
> I've searched high and low on this and found nothing of help. I'm using
> v2.6.2 and trying to write a function that will count how many people from a
> dataset fall under a poverty line of 50% of the mean income.
>
> a9 is my 100-element vector of incomes. I want pa9 to be my vector that
> counts how many of these are classed as in poverty.
>
> My problem is that my command if(a9[i] < mean(a9)/2 ) returns an "argument
> is of length zero" error. But a9[i] is not really of length zero; if I
> remove the if() command and simply set pa9[i] = a9[i] in the loop it comes
> out fine.
>
> I don't think it's a problem with the type of variable either, because if I
> multiply the vector by 2 I get the "correct" output, so I think it's a
> problem with R interpreting my vector as a list of strings or anything.
>
> povertyline = function()
> {
> pa9 = c()
> i=0
>  while(i<=length(a9))
>  {
>    if(a9[i] < mean(a9)/2)
>    {
>    pa9[i] = a9[i]
>    }
>  i = i+1
>  }
> return(length(pa9))
> }
>
> Has anyone any ideas what's going wrong? (Just for clarification: yes, this
> is for my homework. However I've already done the assignment in Excel and
> I'm repeating it to improve my R'ing.)
>
> Thanks a lot,
> Enda
>
>        [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> and provide commented, minimal, self-contained, reproducible code.
>

--
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?

```