Error: $ operator is invalid for atomic vectors for matrix

Question

Here is my code:

datTraits = as.matrix(Phenotype[traitRows, ]);
Col_A = as.data.frame(datTraits$Col_A);

Error in datTraits$Col_A : $ operator is invalid for atomic vectors

I am trying to solve this error but could not find the solution. Thank you for your help!

Answer 1

The 'datTraits' is a matrix . So $ won't work. We can use [

datTraits[, "Col_A"])

In the OP's code, if we are using as.data.frame , note the extraction with $ ie after the )

as.data.frame(datTraits)$Col_A

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If we have a matrix with 5 columns and want to subset the first two columns

as.data.frame(datTraits[, 1:2])

If we are subsetting only a single column, to avoid dropping the dimensions, use drop = FALSE

out <- as.data.frame(datTraits[, "Col_A", drop = FALSE])