quantcut {gtools} | R Documentation |
Create a Factor Variable Using the Quantiles of a Continuous Variable
Description
Create a factor variable using the quantiles of a continuous variable.
Usage
quantcut(x, q = 4, na.rm = TRUE, ...)
Arguments
x |
Continuous variable. |
q |
Either a integer number of equally spaced quantile groups to
create, or a vector of quantiles used for creating groups. Defaults to
|
na.rm |
Boolean indicating whether missing values should be removed when computing quantiles. Defaults to TRUE. |
... |
Optional arguments passed to |
Details
This function uses quantile
to obtain the specified quantiles
of x
, then calls cut
to create a factor variable using
the intervals specified by these quantiles.
It properly handles cases where more than one quantile obtains the same value, as in the second example below. Note that in this case, there will be fewer generated factor levels than the specified number of quantile intervals.
Value
Factor variable with one level for each quantile interval.
Author(s)
Gregory R. Warnes greg@warnes.net
See Also
Examples
## create example data
# testonly{
set.seed(1234)
# }
x <- rnorm(1000)
## cut into quartiles
quartiles <- quantcut(x)
table(quartiles)
## cut into deciles
deciles.1 <- quantcut(x, 10)
table(deciles.1)
# or equivalently
deciles.2 <- quantcut(x, seq(0, 1, by = 0.1))
# testonly{
stopifnot(identical(deciles.1, deciles.2))
# }
## show handling of 'tied' quantiles.
x <- round(x) # discretize to create ties
stem(x) # display the ties
deciles <- quantcut(x, 10)
table(deciles) # note that there are only 5 groups (not 10)
# due to duplicates