Create a Factor Variable Using the Quantiles of a Continuous Variable
Create a factor variable using the quantiles of a continuous variable.
quantcut(x, q=4, na.rm=TRUE, ...)
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 |
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.
Factor variable with one level for each quantile interval.
Gregory R. Warnes greg@warnes.net
## create example data
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) )
## 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 duplicatesPlease choose more modern alternatives, such as Google Chrome or Mozilla Firefox.