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