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Converts a data.table into a matrix, optionally using one
of the columns in the data.table as the matrix rownames.
# S3 method for data.table
as.matrix(x, rownames=NULL, rownames.value=NULL, …)a data.table
optional, a single column name or column number to use as
the rownames in the returned matrix. If TRUE the
key of the data.table will be used if it is a
single column, otherwise the first column in the data.table will
be used.
optional, a vector of values to be used as the
rownames in the returned matrix. It must be the same length
as nrow(x).
Required to be present because the generic `as.matrix` generic has it. Arguments here are not currently used or passed on by this method.
A new matrix containing the contents of x.
as.matrix is a generic function in base R. It dispatches to
as.matrix.data.table if its x argument is a data.table.
The method for data.tables will return a character matrix if there
are only atomic columns and any non-(numeric/logical/complex) column,
applying as.vector to factors and format to other
non-character columns. Otherwise, the usual coercion hierarchy (logical <
integer < double < complex) will be used, e.g., all-logical data frames
will be coerced to a logical matrix, mixed logical-integer will give an
integer matrix, etc.
# NOT RUN {
DT <- data.table(A = letters[1:10], X = 1:10, Y = 11:20)
as.matrix(DT) # character matrix
as.matrix(DT, rownames = "A")
as.matrix(DT, rownames = 1)
as.matrix(DT, rownames = TRUE)
setkey(DT, A)
as.matrix(DT, rownames = TRUE)
# }
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