as.matrix {data.table}  R Documentation 
Converts a data.table
into a matrix
, optionally using one
of the columns in the data.table
as the matrix
rownames
.
## S3 method for class 'data.table'
as.matrix(x, rownames=NULL, rownames.value=NULL, ...)
x 
a 
rownames 
optional, a single column name or column number to use as
the 
rownames.value 
optional, a vector of values to be used as the

... 
Required to be present because the generic 'as.matrix' generic has it. Arguments here are not currently used or passed on by this method. 
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.table
s 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
noncharacter columns. Otherwise, the usual coercion hierarchy (logical <
integer < double < complex) will be used, e.g., alllogical data frames
will be coerced to a logical matrix, mixed logicalinteger will give an
integer matrix, etc.
A new matrix
containing the contents of x
.
data.table
, as.matrix
, data.matrix
array
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)