R/acut.R

In Publish: Format Output of Various Routines in a Suitable Way for Reports and Publication

##' A version of \code{cut} that easily formats the labels and places breaks by default.
##'
##' The formats are supplied by specifiyng the text around the lower (\%l) and upper (\%l) value (see examples).
##' If user specified breaks are supplied, the default labels from \code{cut} are used.
##' If automatic breaks are used, the default labels are a slight modification at the end point of the default from \code{cut}
##' All this can of course be adjusted manually through the format functionality (see below). 
##' 
##' By default, 5 breaks are constructed according to the quantiles with of the input \code{x}.
##' The number of breaks can be adjusted, and default specifying breaks (as in \code{cut}) can be supplied instead.
##'
##' If \code{type} is changed from "\code{default}" to another option, a different formatting template is used.
##' For now the only other option is "\code{age}", which is designed to be well suited to easily group age variables.
##' When \code{type}="\code{age}" only the \code{breaks} argument is used, and it behaves different from otherwise.
##' If a single number is supplied, intervals of length \code{breaks} will automatically be constructed (starting from 0).
##' If a vector is supplied, the intervals are used as in \code{cut} but formatted differently, see examples. 
##' @title Automatic selection and formatting of breaks in \code{cut}
##' @param x a numeric vector which is to be converted to a factor by cutting (passed directly to \code{cut}).
##' @param n number of bins to create based on the empirical quantiles of x. This will be overruled if \code{breaks} is supplied.
##' @param type a high-level formatting option. For now, the only other option than the default setting is "\code{age}". See details and examples.
##' @param format string used to make labels. \%l and \%u identifies the lower and upper value of the breaks respectively. See examples.
##' @param format.low string used specifically on the lowest label.
##' @param format.high string used specifically on the highest label.
##' @param dig.lab integer which is used when labels are not given. It determines the number of digits used in formatting the break numbers. (Passed directly to \code{cut}.)
##' @param right logical, indicating if the intervals should be closed on the right (and open on the left) or vice versa (passed directly to \code{cut}).
##' @param breaks specify breaks manually as in \code{cut}. 
##' @param labels logical, indicating whether or not to make labels or simply use ordered numbers. If TRUE, the labels are constructed as discribed above.
##' @param ... further arguments passed to \code{cut}.
##' @return same as for cut. A vector of 'factors' is created, unless 'labels=FALSE'. 
##' @examples
##' data(Diabetes) # load dataset
##'
##' ## The default uses format similar to cut
##' chol.groups <- acut(Diabetes$chol)
##' table(chol.groups)
##'
##' ## The formatting can easily be changed
##' chol.groups <- acut(Diabetes$chol,format="%l-%u",n=5)
##' table(chol.groups)
##' 
##' ## The default is to automatic place the breaks, so the number of this can easily be changed.
##' chol.groups <- acut(Diabetes$chol,n=7)
##' table(chol.groups)
##'
##' ## Manually setting format and breaks
##' age.groups <- acut(Diabetes$age,format="%l-%u",breaks=seq(0,100,by=10))
##' table(age.groups)
##'
##' ## Other variations 
##' age.groups <- acut(Diabetes$age,
##'                    format="%l-%u",
##'                    format.low="below %u",
##'                    format.high="above %l",
##'                    breaks=c(0, seq(20,80,by=10), Inf))
##' table(age.groups)
##' 
##' BMI.groups <- acut(Diabetes$BMI,
##'                    format="BMI between %l and %u",
##'                    format.low="BMI below %u",
##'                    format.high="BMI above %l")
##' table(BMI.groups)
##' org(as.data.frame(table(BMI=BMI.groups)))
##'
##' ## Instead of using the quantiles, we can specify equally spaced breaks,
##' ## but still get the same formatting
##' BMI.grouping <-
##'    seq(min(Diabetes$BMI,na.rm=TRUE), max(Diabetes$BMI,na.rm=TRUE), length.out=6)
##' BMI.grouping[1] <- -Inf # To get all included
##' BMI.groups <- acut(Diabetes$BMI,
##'                    breaks=BMI.grouping,
##'                    format="BMI between %l and %u",
##'                    format.low="BMI below %u",
##'                    format.high="BMI above %l")
##' table(BMI.groups)
##' org(as.data.frame(table(BMI=BMI.groups)))
##'
##' ## Using type="age"
##' ## When using type="age", categories of 10 years are constructed by default.
##' ## The are formatted to be easier to read when the values are ages.
##' table(acut(Diabetes$age, type="age"))
##'
##' ## This can be changes with the breaks argument.
##' ## Note that this is diffent from cut when breaks is a single number.
##' table(acut(Diabetes$age, type="age", breaks=20))
##'
##' ## Of course We can also supply the breaks manually.
##' ## The formatting depends on whether or not all the values fall within the breaks:
##' ## All values within the breaks
##' table(acut(Diabetes$age, type="age", breaks=c(0, 30, 50, 80, 100)))
##' ## Some values below and above the breaks
##' table(acut(Diabetes$age, type="age", breaks=c(30, 50, 80))) 
##' 
##' @author Anders Munch
##' @export
acut <- function(x,n=5,type="default",
                 format=NULL,format.low=NULL,format.high=NULL,dig.lab=3,right=TRUE,breaks,labels=TRUE,...){
    stopifnot(n>1)
    update.label <- function(str,low=NULL,upper=NULL,low.str="%l",upper.str="%u"){
        if(is.null(low)) low <- low.str
        if(is.null(upper)) upper <- upper.str
        new.label <- str
        new.label <- sub(low.str, low, new.label)
        new.label <- sub(upper.str, upper, new.label)
        return(new.label)
    }
    if(type=="age"){
        min.x <- min(x, na.rm=TRUE)
        max.x <- max(x, na.rm=TRUE)
        if(missing(breaks))
            breaks <- 10
        if(length(breaks)==1){
            if(as.integer(breaks)!=breaks)
                warning("When using type=\"age\", it makes most sense with intervals with integer length.")
            breaks <- seq(floor(min.x/breaks)*breaks, ceiling(max.x/breaks)*breaks, by=breaks)
        }
        if(any(!(as.integer(breaks) == breaks)))
            warning("When using type=\"age\", it makes most sense with integer-valued breaks points.")
        breaks <- sort(breaks)
        if(min.x<breaks[1]) breaks <- c(-Inf, breaks)
        if(max.x>breaks[length(breaks)]) breaks <- c(breaks, Inf)
        ## Find way to handle right=FALSE -- maybe not relevant for the type?
        pre.cut <- acut(x=x, breaks=breaks, right=FALSE)
        age.labels <- paste0(breaks[-length(breaks)], "-", (breaks[-1]-1))
        if(breaks[1] == -Inf) age.labels[1] <- paste("younger than", breaks[2])
        if(breaks[length(breaks)] == Inf) age.labels[length(age.labels)] <- paste(breaks[length(breaks)-1], "or older")
        pre.cut <- factor(pre.cut, levels=levels(pre.cut),
                          labels=age.labels)
        return(pre.cut)
    }
    if(missing(breaks)){
        breaks <- as.numeric(quantile(x, seq(0,1,length.out=n+1), na.rm=TRUE))
        breaks[1] <- -Inf
        breaks[length(breaks)] <- Inf
        if(is.null(format.low)){
            if(right)
                format.low <- "<= %u"
            else
                format.low <- "< %u"
        }
        if(is.null(format.high)){
            if(right)
                format.high <- "> %l"
            else
                format.high <- ">= %l"
        }
    }
    if(labels) labels <- NULL
    out <- cut(x,breaks=breaks,right=right,labels=labels,dig.lab=dig.lab)
    if(!is.null(c(format,format.low,format.high)) & is.null(labels)){
        ## To keep consistency with labels from cut
        ## and because dig.lab in cut is quite clever, extract the breaks from here.
        default.labels <- levels(out)
        breaks <- unlist(strsplit(gsub(" ", "", paste(chartr("(]","  ",default.labels),collapse=",")), ","))
        breaks <- breaks[c(seq(1,length(breaks)-1,by=2),length(breaks))]
        out.labels <- levels(out)
        if(!is.null(format))
            out.labels <- mapply(
                function(a,b) update.label(format,low=a,upper=b),
                breaks[1:(length(breaks)-1)],
                breaks[2:(length(breaks))]
            )
        if(!is.null(format.low))
            out.labels[1] <- update.label(format.low,low=breaks[1],upper=breaks[2])
        if(!is.null(format.high))
            out.labels[length(out.labels)] <- update.label(format.high,
                                                           low=breaks[length(breaks)-1],
                                                           upper=breaks[length(breaks)])
        levels(out) <- out.labels
    }
    return(out)
}