acut {Publish}

Automatic selection and formatting of breaks in cut

Description

A version of cut that easily formats the labels and places breaks by default.

Usage

acut(
  x,
  n = 5,
  type = "default",
  format = NULL,
  format.low = NULL,
  format.high = NULL,
  dig.lab = 3,
  right = TRUE,
  breaks,
  labels = TRUE,
  ...
)

Arguments

x

a numeric vector which is to be converted to a factor by cutting (passed directly to cut).

n

number of bins to create based on the empirical quantiles of x. This will be overruled if breaks is supplied.

type

a high-level formatting option. For now, the only other option than the default setting is "age". See details and examples.

format

string used to make labels. %l and %u identifies the lower and upper value of the breaks respectively. See examples.

format.low

string used specifically on the lowest label.

format.high

string used specifically on the highest label.

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 cut.)

right

logical, indicating if the intervals should be closed on the right (and open on the left) or vice versa (passed directly to cut).

breaks

specify breaks manually as in cut.

labels

logical, indicating whether or not to make labels or simply use ordered numbers. If TRUE, the labels are constructed as discribed above.

...

further arguments passed to cut.

Details

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 cut are used. If automatic breaks are used, the default labels are a slight modification at the end point of the default from 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 x. The number of breaks can be adjusted, and default specifying breaks (as in cut) can be supplied instead.

If type is changed from "default" to another option, a different formatting template is used. For now the only other option is "age", which is designed to be well suited to easily group age variables. When type="age" only the breaks argument is used, and it behaves different from otherwise. If a single number is supplied, intervals of length breaks will automatically be constructed (starting from 0). If a vector is supplied, the intervals are used as in cut but formatted differently, see examples.

Value

same as for cut. A vector of 'factors' is created, unless 'labels=FALSE'.

Author(s)

Anders Munch

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)))