| 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 dataframe to numeric mode and then binding them together as the columns ofa matrix. Factors and ordered factors are replaced by their internalcodes.
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 matrixshould have character (rather than |
Details
Logical and factor columns are converted to integers. Charactercolumns are first converted to factors and then to integers. Any othercolumn which is not numeric (according tois.numeric) isconverted byas.numeric or, for S4 objects,as(, "numeric"). If all columns are integer (afterconversion) the result is an integer matrix, otherwise a numeric(double) matrix.
Value
Ifframe inherits from class"data.frame", an integer ornumeric matrix of the same dimensions asframe, with dimnamestaken from therow.names (orNULL, depending onrownames.force) andnames.
Otherwise, the result ofas.matrix.
Note
The default behaviour for data frames differs fromR < 2.5.0 whichalways 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
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)