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rrandomfrequencysample

R: how to sample rows with custom frequencies

I have a data frame in R that has two columns, one with last names, the other with the frequency of each last name. I would like to randomly select last names based on the frequency values (0 -> 1).

So far I have tried using the sample function, but it doesn't allow for specific frequencies for each value. Not sure if this is possible :/

Solution 
  • df1 <- data.frame(names = c("John","Mary"),freq=c(0.2,0.8))
df1
#   names freq
# 1  John  0.2
# 2  Mary  0.8

set.seed(1)
sample100 <- sample(
  x = df1$names,
  size = 100,
  replace=TRUE,
  prob=df1$freq)

table(sample100)
# sample100
# John Mary 
#   17   83