[R] what does negative indexing in a matrix mean?

[Stephan Kolassa]

"take all of the matrix *except* those indices", so XW4[,-2] is the 
matrix XW4 with the 2nd column *deleted*.

Cheers,
Stephan


Itziar Frades Alzueta schrieb:
> Hi,
> 
> Does anyone know what the negative indexing of a matrix mean?
> 
>  
> 
> I am using the RWeka and this evaluate classifier does not work on new
> data like this
> 
>  
> 
> e <- evaluate_Weka_classifier(m1235,newdata=XW4, complexity =
> FALSE,class = FALSE) 
> 
>  
> 
> while it work with negative indexing:
> 
>  
> 
> e <- evaluate_Weka_classifier(m1235,newdata=XW4[,-2], complexity =
> FALSE,class = FALSE)
> 
>  
> 
> Although I do not understand what negative indexing of a matrix means,
> or whether it produces any transformation.
> 
>  
> 
> Regards,
> 
>  
> 
> Itziar Frades
> 
> 
>  
>  
>  
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