Percentile function in R

gistfile1.r

# CALCULATING PERCENTILES IN R 
#
# a basic percentile function using "ecdf" [Empirical Cumulative Distribution Function]
# using a data file "percentiledata" with variable VALUE
percentileFUN <- ecdf(percentiledata$VALUE)
percentileFUN
percentileFUN(percentiledata$VALUE)
# write the percentile values to the source file
percentiledata$pctl <- percentilefunction(percentiledata$VALUE)
#
#
#
# to run separate percentiles on the VALUE by the groups in the data (variable GROUP)
# uses the "mutate" function in plyr
# (see http://www.seananderson.ca/2013/12/01/plyr.html)
require(plyr)
newpercentiledata <- ddply(percentiledata, "GROUP", mutate, pctl ={
  percentileFUN <- ecdf(VALUE)
  percentileFUN
  percentileFUN(VALUE)
})
#  
# 
# version for WES2013
#
newWU_driver_melt <- ddply(WU_driver_melt, "variable", mutate, pctl ={
  percentileFUN <- ecdf(value)
  percentileFUN
  percentileFUN(value)
})
#
# REFERENCES
# http://www.jstatsoft.org/v40/i01
# http://www.seananderson.ca/2013/12/01/plyr.html
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})
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