cut2 function

Cut a Numeric Variable into Intervals

cut2 is a function like cut but left endpoints are inclusive and labels are of the form [lower, upper), except that last interval is [lower,upper]. If cuts are given, will by default make sure that cuts include entire range of x. Also, if cuts are not given, will cut x into quantile groups (g given) or groups with a given minimum number of observations (m). Whereas cut creates a category object, cut2 creates a factor object. m is not guaranteed but is a target.

cutGn guarantees that the grouped variable will have a minimum of m observations in any group. This is done by an exhaustive algorithm that runs fast due to being coded in Fortran.

cut2(x, cuts, m=150, g, levels.mean=FALSE, digits, minmax=TRUE,
oneval=TRUE, onlycuts=FALSE, formatfun=format, ...)

cutGn(x, m, what=c('mean', 'factor', 'summary', 'cuts', 'function'), rcode=FALSE)

Arguments

• x: numeric vector to classify into intervals
• cuts: cut points
• m: desired minimum number of observations in a group. The algorithm does not guarantee that all groups will have at least m observations.
• g: number of quantile groups
• levels.mean: set to TRUE to make the new categorical vector have levels attribute that is the group means of x instead of interval endpoint labels
• digits: number of significant digits to use in constructing levels. Default is 3 (5 if levels.mean=TRUE)
• minmax: if cuts is specified but min(x)<min(cuts) or max(x)>max(cuts), augments cuts to include min and max x
• oneval: if an interval contains only one unique value, the interval will be labeled with the formatted version of that value instead of the interval endpoints, unless oneval=FALSE
• onlycuts: set to TRUE to only return the vector of computed cuts. This consists of the interior values plus outer ranges.
• formatfun: formatting function, supports formula notation (if rlang is installed)
• ...: additional arguments passed to formatfun
• what: specifies the kind of vector values to return from cutGn, the default being like 'levels.mean' of cut2. Specify 'summary' to return a numeric 3-column matrix that summarizes the intervals satisfying the m requirement. Use what='cuts' to only return the vector of computed cutpoints. To create a function that will recode the variable in play using the same intervals as computed by cutGn, specify what='function'. This function will have a what argument to allow the user to decide later whether to recode into interval means or into a factor variable.
• rcode: set to TRUE to run the cutgn algorithm in R. This is useful for speed comparisons with the default compiled code.

Returns

a factor variable with levels of the form [a,b) or formatted means (character strings) unless onlycuts is TRUE in which case a numeric vector is returned

See Also

cut, quantile, combine.levels

Examples

set.seed(1)
x <- runif(1000, 0, 100)
z <- cut2(x, c(10,20,30))
table(z)
table(cut2(x, g=10))      # quantile groups
table(cut2(x, m=50))      # group x into intevals with at least 50 obs.

table(cutGn(x, m=50, what='factor'))
f <- cutGn(x, m=50, what='function')
f
f(c(-1, 2, 10), what='mean')
f(c(-1, 2, 10), what='factor')
## Not run:

  x <- round(runif(200000), 3)
  system.time(a <- cutGn(x, m=20))              # 0.02s
  system.time(b <- cutGn(x, m=20, rcode=TRUE))  # 1.51s
  identical(a, b)
## End(Not run)