| % File src/library/base/man/data.matrix.Rd |
| % Part of the R package, https://www.R-project.org |
| % Copyright 1995-2008 R Core Team |
| % Distributed under GPL 2 or later |
| |
| \name{data.matrix} |
| \alias{data.matrix} |
| \title{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{ |
| \item{frame}{a data frame whose components are logical vectors, |
| factors or numeric vectors.} |
| \item{rownames.force}{logical indicating if the resulting matrix |
| should have character (rather than \code{NULL}) |
| \code{\link{rownames}}. The default, \code{NA}, uses \code{NULL} |
| rownames if the data frame has \sQuote{automatic} row.names or for a |
| zero-row data frame.} |
| } |
| \details{ |
| Logical and factor columns are converted to integers. Any other |
| column which is not numeric (according to \code{\link{is.numeric}}) is |
| converted by \code{\link{as.numeric}} or, for S4 objects, |
| \code{\link{as}(, "numeric")}. If all columns are integer (after |
| conversion) the result is an integer matrix, otherwise a numeric |
| (double) matrix. |
| } |
| \value{ |
| If \code{frame} inherits from class \code{"data.frame"}, an integer or |
| numeric matrix of the same dimensions as \code{frame}, with dimnames |
| taken from the \code{row.names} (or \code{NULL}, depending on |
| \code{rownames.force}) and \code{names}. |
| |
| Otherwise, the result of \code{\link{as.matrix}}. |
| } |
| \note{ |
| The default behaviour for data frames differs from \R < 2.5.0 which |
| always gave the result character rownames. |
| } |
| \seealso{ |
| \code{\link{as.matrix}}, |
| \code{\link{data.frame}}, |
| \code{\link{matrix}}. |
| } |
| \references{ |
| Chambers, J. M. (1992) |
| \emph{Data for models.} |
| Chapter 3 of \emph{Statistical Models in S} |
| eds J. M. Chambers and T. J. Hastie, Wadsworth & Brooks/Cole. |
| } |
| \examples{ |
| 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) |
| } |
| \keyword{array} |