Below are the solutions to these exercises on creating a sample dataset.
#################### # # # Exercise 1 # # # #################### set.seed(1235) fair_coin <- sample(c(0,1), 100, replace = TRUE) #################### # # # Exercise 2 # # # #################### set.seed(2312) hourselect1 <- sample(c(8:19),10,replace=TRUE) hourselect1
## [1] 14 19 16 18 13 15 8 10 10 16
#################### # # # Exercise 3 # # # #################### probs <- c(0.05,0.08,0.16,0.17,0.18,0.14,0.08,0.06,0.03,0.03,0.01,0.01) sum(probs)
## [1] 1
#################### # # # Exercise 4 # # # #################### set.seed(1976) hourselect2 <- sample(c(8:19),10,replace=TRUE,prob = probs) hourselect2
## [1] 15 11 12 15 12 9 14 12 10 9
#################### # # # Exercise 5 # # # #################### coin <- rep(c(0,1),each=5) coin
## [1] 0 0 0 0 0 1 1 1 1 1
probs <- rep(c(0.08,0.12),each=5) sum(probs)
## [1] 1
#################### # # # Exercise 6 # # # #################### set.seed(345124) biased_coin <- sample(coin, 100, replace = TRUE,prob=probs) #################### # # # Exercise 7 # # # #################### sum(fair_coin)
## [1] 52
sum(biased_coin)
## [1] 63
#################### # # # Exercise 8 # # # #################### startDate <- as.Date("2010-02-09") endDate <- as.Date("2005-02-09") seqDates <- seq.Date(startDate, endDate, by = "-1 month") #################### # # # Exercise 9 # # # #################### RevSeqDates <- rev(seqDates) #################### # # # Exercise 10 # # # #################### set.seed(10) sample(RevSeqDates,20,replace=FALSE)
## [1] "2007-08-09" "2006-08-09" "2007-03-09" "2008-06-09" "2005-06-09" ## [6] "2006-02-09" "2006-05-09" "2006-04-09" "2007-10-09" "2006-12-09" ## [11] "2007-11-09" "2007-06-09" "2005-07-09" "2009-03-09" "2006-06-09" ## [16] "2006-09-09" "2005-04-09" "2006-01-09" "2006-07-09" "2008-01-09"
Hi Avi! Thanks for an exercise. I’ve accomplished task #8 using seq() function instead of seq.Date(). I don’t see any difference in the output. Is there any?
Hi,
According to the R documentation (https://stat.ethz.ch/R-manual/R-devel/library/base/html/seq.Date.html), there is no difference between seq and seq.Date, since seq.Date is a method of seq function for objects of class “Date”.
Bottom line: you can use either of them and get same results.
Best Regards,
Avi
Thanks, Avi. The exercises were simple but I had never made a sequence of dates. Really helpful thing to have in my repertoire.