| data.matrix {base} | R Documentation |
Return the matrix obtained by converting all the variables in a data frame to numeric mode and then binding them together as the columns of a matrix. Factors and ordered factors are replaced by their internal codes.
data.matrix(frame, rownames.force = NA)
frame |
a data frame whose components are logical vectors, factors or numeric vectors. |
rownames.force |
logical indicating if the resulting matrix
should have character (rather than NULL)
rownames. The default, NA, uses NULL
rownames if the data frame has ‘automatic’ row.names or for a
zero-row data frame. |
Supplying a data frame with columns which are not numeric, factor or logical is an error. A warning is given if any non-factor column has a class, as then information can be lost.
If frame inherits from class "data.frame", an integer or
numeric matrix of the same dimensions as frame, with dimnames
taken from the row.names (or NULL, depending on
rownames.force) and names.
Otherwise, the result of as.matrix.
The default behaviour for data frames differs from R < 2.5.0 which always gave the result character rownames.
Chambers, J. M. (1992) Data for models. Chapter 3 of Statistical Models in S eds J. M. Chambers and T. J. Hastie, Wadsworth & Brooks/Cole.
as.matrix,
data.frame,
matrix.
DF <- data.frame(a=1:3, b=letters[10:12],
c=seq(as.Date("2004-01-01"), by = "week", len = 3),
stringsAsFactors = TRUE)
data.matrix(DF[1:2])
data.matrix(DF) # gives a warning and quotes dates as #days since 1970.