| % File src/library/stats/man/replications.Rd |
| % Part of the R package, https://www.R-project.org |
| % Copyright 1995-2014 R Core Team |
| % Distributed under GPL 2 or later |
| |
| \name{replications} |
| \title{Number of Replications of Terms} |
| \usage{ |
| replications(formula, data = NULL, na.action) |
| } |
| \alias{replications} |
| \arguments{ |
| \item{formula}{a formula or a terms object or a data frame.} |
| \item{data}{a data frame used to find the objects in \code{formula}.} |
| \item{na.action}{function for handling missing values. Defaults to |
| a \code{na.action} attribute of \code{data}, then |
| a setting of the option \code{na.action}, or \code{na.fail} if that |
| is not set.} |
| } |
| \description{ |
| Returns a vector or a list of the number of replicates for |
| each term in the formula. |
| } |
| \details{ |
| If \code{formula} is a data frame and \code{data} is missing, |
| \code{formula} is used for \code{data} with the formula \code{~ .}. |
| |
| Any character vectors in the formula are coerced to factors. |
| } |
| \value{ |
| A vector or list with one entry for each term in the formula giving |
| the number(s) of replications for each level. If all levels are |
| balanced (have the same number of replications) the result is a |
| vector, otherwise it is a list with a component for each terms, |
| as a vector, matrix or array as required. |
| |
| A test for balance is \code{!is.list(replications(formula,data))}. |
| } |
| \references{ |
| Chambers, J. M., Freeny, A and Heiberger, R. M. (1992) |
| \emph{Analysis of variance; designed experiments.} |
| Chapter 5 of \emph{Statistical Models in S} |
| eds J. M. Chambers and T. J. Hastie, Wadsworth & Brooks/Cole. |
| } |
| \author{ |
| The design was inspired by the S function of the same name described |
| in Chambers \emph{et al} (1992). |
| } |
| |
| \seealso{\code{\link{model.tables}}} |
| |
| \examples{ |
| ## From Venables and Ripley (2002) p.165. |
| N <- c(0,1,0,1,1,1,0,0,0,1,1,0,1,1,0,0,1,0,1,0,1,1,0,0) |
| P <- c(1,1,0,0,0,1,0,1,1,1,0,0,0,1,0,1,1,0,0,1,0,1,1,0) |
| K <- c(1,0,0,1,0,1,1,0,0,1,0,1,0,1,1,0,0,0,1,1,1,0,1,0) |
| yield <- c(49.5,62.8,46.8,57.0,59.8,58.5,55.5,56.0,62.8,55.8,69.5, |
| 55.0, 62.0,48.8,45.5,44.2,52.0,51.5,49.8,48.8,57.2,59.0,53.2,56.0) |
| |
| npk <- data.frame(block = gl(6,4), N = factor(N), P = factor(P), |
| K = factor(K), yield = yield) |
| replications(~ . - yield, npk) |
| } |
| \keyword{models} |