[R] counting the number of ones in a vector

[Gavin Simpson]

On Thu, 2010-03-04 at 00:03 +0100, Randall Wrong wrote:
> Thanks to all of you !
> 
> (Benjamin Nutter, Henrique Dallazuanna, Tobias Verbeke, Jorge Ivan
> Velez, David Reinke and Gavin Simpson)
>  
>  
> x <- c(1, 1, 1, NA, NA, 2, 1, NA)
>  
> > table(x)["1"]
> 1 
> 4 
>  
> Why do I get two numbers ?

It is a printing a named vector. The 1 is the "group" of factor level,
the 4 is the "count", try:

unname(table(x)[1])

and

str(table(x)[1])

etc to see what is going on.

HTH

G

>  
> Thanks,
> Randall
>  
> 
>  
> 2010/2/26 Nutter, Benjamin <NutterB at ccf.org>
>         But if x has any missing values:
>         
>         > x <- c(1, 1, 1, NA, NA, 2, 1, NA)
>         >
>         > sum( x == 1)
>         [1] NA
>         >
>         > sum(x==1, na.rm=TRUE)
>         [1] 4
>         
>         
>         
>         
>         
>         -----Original Message-----
>         From: r-help-bounces at r-project.org
>         [mailto:r-help-bounces at r-project.org] On Behalf Of Henrique
>         Dallazuanna
>         Sent: Friday, February 26, 2010 9:47 AM
>         To: Randall Wrong
>         Cc: r-help at r-project.org
>         Subject: Re: [R] counting the number of ones in a vector
>         
>         Try:
>         
>         sum(x == 1)
>         
>         On Fri, Feb 26, 2010 at 11:40 AM, Randall Wrong
>         <randall.wrong at gmail.com> wrote:
>         > Dear R users,
>         >
>         > I want to count the number of ones in a vector x.
>         >
>         > That's what I did : length( x[x==1] )
>         >
>         > Is that a good solution ?
>         > Thank you very much,
>         > Randall
>         >
>         >        [[alternative HTML version deleted]]
>         >
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>         
>         
>         
>         --
>         Henrique Dallazuanna
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