[R] strange behavior of R

[David Winsemius]

On Jan 8, 2010, at 5:57 PM, Fahim wrote:

>
> Hi
> I observed an interesting behavior of R. Can you find where is the  
> bug, or
> it is not a bug but made deliberately.
> - Hide quoted text -
>
>
>> arr = c();                        #defined the empty array
>> a= c("x1", "x2");
>> b = c("y1", "y2");
>> arr = rbind(arr,a);            #row bind the first character array -a
>> arr = rbind(arr,b);            # row bind the second character  
>> array-b
>
> Everything ok upto this point, arr content is displayed as follows
>> arr
>  [,1] [,2]
> a "x1" "x2"
> b "y1" "y2"
>
> Now I delete any row:
> arr = arr[-1,];
>
> The value of arr is :
>> arr
> [1] "y1" "y2"
>
> Problem: I want to access the first row now using:
>> arr[1, ]
> Error in arr[1, 1] : incorrect number of dimensions

use arr[ , -1, drop=FALSE] to avoid loosing dimensions.

?"["

-- 
David.
>
> Though it is showing the value  as under:
>> arr[1]
> [1] "y1"
>
>> arr[2]
> [1] "y2"
>
>
> I think, when there is single row, R is considering it as an array  
> and not
> as matrix. But why it is so?????????????/
>


Because you didn't red the manual.

David Winsemius, MD
Heritage Laboratories
West Hartford, CT