[R] How to avoid "$ operator is invalid for atomic vectors"

[Erik Iverson]

Hello -

cruz wrote:
> Hi,
> 
> I am writing this in a wrong way, can someone please correct me?
> 
>> A <- matrix()
>> length(A) <- 6
>> dim(A) <- c(3,2)
>> colnames(A) <- c("X","Y")
>> A
>       X  Y
> [1,] NA NA
> [2,] NA NA
> [3,] NA NA
>> A$X
> Error in A$X : $ operator is invalid for atomic vectors

A[, "X"] may be what you want?

See the details of ?Extract about how '$' only works on recursive 
(list-like) objects, of which your matrix A is not one of.

> 
> Thanks,
> cruz
> 
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