[R] Removing columns from a matrix using a list

[Gabor Grothendieck]

Here are three ways:

subset(iris, select = -c(Sepal.Length, Species))

nm <- c("Sepal.Length", "Species")
iris[,!names(iris) %in% nm]

nm <- c("Sepal.Length", "Species")
iris[,setdiff(names(iris), nm)]

On 3/28/06, Peter Wilkinson <pwilkinson_m at xbioinformatics.org> wrote:
> How does one remove columns either by name ("Exp1", "Exp2", "Exp3", ...
> "Exp100") or by column number from a matrix or data.frame using a list of
> names mynames = ("Exp10,"Exp20","Exp55","Exp67")
>
> I would something in the form of (I know this does not work):
>
> myMatrixEdited = myMatrix[,-mynames]
>
> Or I would like to find the column numbers of the names in the list, and use
> the column numbers to remove the columns in the matrix or data.frame.
>
>
> Peter W.
>
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