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% File src/library/base/man/nrow.Rd
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% File src/library/base/man/nrow.Rd
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% Part of the R package, https://www.R-project.org
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% Part of the R package, https://www.R-project.org
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% Copyright 1995-2007 R Core Team
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% Copyright 1995-2018 R Core Team
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% Distributed under GPL 2 or later
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% Distributed under GPL 2 or later
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\name{nrow}
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\name{nrow}
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\title{The Number of Rows/Columns of an Array}
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\title{The Number of Rows/Columns of an Array}
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\usage{
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\usage{
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\alias{nrow}
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\alias{nrow}
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\alias{NROW}
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\alias{NROW}
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\alias{ncol}
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\alias{ncol}
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\alias{NCOL}
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\alias{NCOL}
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\arguments{
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\arguments{
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  \item{x}{a vector, array or data frame}
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  \item{x}{a vector, array, data frame, or \code{\link{NULL}}.}
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}
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}
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\description{
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\description{
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  \code{nrow} and \code{ncol} return the number of rows or columns
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  \code{nrow} and \code{ncol} return the number of rows or columns
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  present in \code{x}.
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  present in \code{x}.
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  \code{NCOL} and \code{NROW} do the same treating a vector as
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  \code{NCOL} and \code{NROW} do the same treating a vector as
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  1-column matrix.
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  1-column matrix, even a 0-length vector, compatibly with
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  \code{\link{as.matrix}()} or \code{\link{cbind}()}, see the example.
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}
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}
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\references{
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\references{
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  Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988)
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  Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988)
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  \emph{The New S Language}.
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  \emph{The New S Language}.
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  Wadsworth & Brooks/Cole (\code{ncol} and \code{nrow}.)
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  Wadsworth & Brooks/Cole (\code{ncol} and \code{nrow}.)
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}
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}
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\seealso{
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\seealso{
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  \code{\link{dim}} which returns \emph{all} dimensions;
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  \code{\link{dim}} which returns \emph{all} dimensions;
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  \code{\link{array}}, \code{\link{matrix}}.
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  \code{\link{array}}, \code{\link{matrix}}.
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}
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}
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\value{an \code{\link{integer}} of length 1 or \code{\link{NULL}}.}
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\value{an \code{\link{integer}} of length 1 or \code{\link{NULL}}, the
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  latter only for \code{ncol} and \code{nrow}.}
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\examples{
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\examples{
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ma <- matrix(1:12, 3, 4)
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ma <- matrix(1:12, 3, 4)
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nrow(ma)   # 3
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nrow(ma)   # 3
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ncol(ma)   # 4
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ncol(ma)   # 4
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ncol(array(1:24, dim = 2:4)) # 3, the second dimension
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ncol(array(1:24, dim = 2:4)) # 3, the second dimension
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NCOL(1:12) # 1
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NCOL(1:12) # 1
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NROW(1:12) # 12
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NROW(1:12) # 12
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## as.matrix() produces 1-column matrices from 0-length vectors,
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## and so does cbind() :
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dim(as.matrix(numeric())) # 0 1
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dim(    cbind(numeric())) # ditto
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## consequently, NCOL(.) gives 1, too :
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NCOL(numeric()) # 1 and hence
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NCOL(NULL)      # 1
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}
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}
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\keyword{array}
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\keyword{array}