vectorization

Here I go again with ave():

mydata$md <- ave(mydata$income, mydata$education, FUN=median, na.rm=TRUE)

IMHO it's one of the most under-rated helper functions in R.

Andy
From: Dimitri Joe

Hi there,

I have a data frame (mydata) with 1 numeric variable (income) 
and 1 factor (education). I want a new column in this data 
with the median income for each education level. A obviously 
inneficient way to do this is

for ( k in 1: nrow(mydata) )            {
l <- mydata$education[k]
mydata$md[k] <- median(mydata$income[mydata$education==l],na.rm=T)
                                                    }

Since mydata has nearly 30.000 rows, this will be done not 
untill the end of this month. I thus need some help for 
vectorizing this, please.

Thanks,

Dimitri

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