[R] Use of paste with apply()

[Austin, Matt]

The apply function is passing each row of you matrix as a single vector into
paste.  If paste receives a single vector and collapse is NULL, it will
simply coerce the vector into a character vector. 

However, when you collapse instead of sep

> test <- matrix( as.character(1:4), 2)
> apply(test, 1, paste, sep="+")
     [,1] [,2]
[1,] "1"  "2" 
[2,] "3"  "4" 

> apply(test, 1, paste, collapse="+")
[1] "1+3" "2+4"

Which may be closer to what you were expecting, but I'm just guessing.

--Matt


> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch
> [mailto:r-help-bounces at stat.math.ethz.ch]On Behalf Of Kjetil 
> Brinchmann
> halvorsen
> Sent: Sunday, November 06, 2005 5:34 AM
> To: r-help at stat.math.ethz.ch
> Subject: [R] Use of paste with apply()
> 
> 
> I was surprised by:
> 
>  > test <- matrix( as.character(1:4), 2)
>  > test
>       [,1] [,2]
> [1,] "1"  "3"
> [2,] "2"  "4"
>  > apply(test, 1, paste, sep="+")
>       [,1] [,2]
> [1,] "1"  "2"
> [2,] "3"  "4"
>  > apply(test, 1, paste, sep="*")
>       [,1] [,2]
> [1,] "1"  "2"
> [2,] "3"  "4"
>  > te <- matrix(1:4, 2)
>  > te
>       [,1] [,2]
> [1,]    1    3
> [2,]    2    4
>  > apply(te, 1, sum)
> [1] 4 6
> 
> Why doesn't paste behave in apply as sum?
> 
> Kjetil
> 
> 
> -- 
> 
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