Question

I’m using the rep() function to repeat each element in a string a number of times. Each character I have contains information for a state, and I need the first three elements of the character vector repeated three times, and the fourth element repeated five times.

So lets say I have the following character vectors.

al <- c("AlabamaCity", "AlabamaCityST", "AlabamaCityState", "AlabamaZipCode") 
ak <- c("AlaskaCity", "AlaskaCityST", "AlaskaCityState", "AlaskaZipCode")
az <- c("ArizonaCity", "ArizonaCityST", "ArizonaCityState", "ArizonaZipCode")
ar <- c("ArkansasCity", "ArkansasCityST", "ArkansasCityState", "ArkansasZipCode")

I want to end up having the following output.

AlabamaCity
AlabamaCity
AlabamaCity
AlabamaCityST
AlabamaCityST
AlabamaCityST
AlabamaCityState
AlabamaCityState
AlabamaCityState
AlabamaZipCode
AlabamaZipCode
AlabamaZipCode
AlabamaZipCode
AlabamaZipCode
AlabamaZipCode
...

I was able to get the desired output with the following command, but it’s a little inconvenient when I’m running through all fifty states. Plus, I might have another column with 237 cities in Alabama, and I’ll inevitably run into problems matching up the names in the first column with the values in the second column.

   dat = data.frame(name=c(rep(al[1:3],each=3), rep(al[4],each=6), 
                rep(ak[1:3],each=3), rep(ak[4],each=6)))
   dat


   dat2 = data.frame(name=c(rep(al[1:3],each=3), rep(al[4],each=6), 
                rep(ak[1:3],each=3), rep(ak[4],each=6)),
                city=c(rep("x",each=15), rep("y",each=15)))
   dat2

Of course, in real life, the ‘x’ and ‘y’ won’t be single values.

So my question concerns if there is a more efficient way of performing this task. And closely related to the question, when does it become important to ditch procedural programming in favor of OOP in R. (not a programmer, so the second part may be a really stupid question) More importantly, is this a task where I should look for a oop related solution.

Answer 1

According to ?rep, times= can be a vector. So, how about this:

dat <- data.frame(name=rep(al, times=c(3,3,3,6)))

It would also be more convenient if your “state” data were in a list.

stateData <- list(al,ak,az,ar)
Data <- lapply(stateData, function(x) data.frame(name=rep(x, times=c(3,3,3,6))))
Data <- do.call(rbind, Data)