| data.matrix {base} | R Documentation |
Convert a Data Frame to a Numeric Matrix
Description
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.
Usage
data.matrix(frame, rownames.force = NA)
Arguments
frame |
a data frame whose components are logical vectors, factors or numeric or character vectors. |
rownames.force |
logical indicating if the resulting matrix
should have character (rather than |
Details
Logical and factor columns are converted to integers. Character
columns are first converted to factors and then to integers. Any other
column which is not numeric (according to is.numeric) is
converted by as.numeric or, for S4 objects,
as(, "numeric"). If all columns are integer (after
conversion) the result is an integer matrix, otherwise a numeric
(double) matrix.
Value
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.
Note
The default behaviour for data frames differs from R < 2.5.0 which always gave the result character rownames.
References
Chambers JM (1992). “Data for Models.” In Chambers JM, Hastie TJ (eds.), Statistical Models in S, chapter 3. Wadsworth & Brooks/Cole.
See Also
as.matrix,
data.frame,
matrix.
Examples
DF <- data.frame(a = 1:3, b = letters[10:12],
c = seq(as.Date("2004-01-01"), by = "week", length.out = 3),
stringsAsFactors = TRUE)
data.matrix(DF[1:2])
data.matrix(DF)