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The setup is: "Suppose that you have a population of 10,000 and 6,000 people are Democrats. We simulate survey sampling from this hypothetical population. First, generate a vector of the population in R. Then, create 500 random samples of size n = 1,000."

My code so far is:

pop<-c(rep("Democrat", 6000), rep("Republican", 4000))


nTrials <- 500
n <- 1000
results <- rep(NA, nTrials)

for(i in 1:nTrials)
{
  sampled <- sample(x=pop, size=n, replace=FALSE)
  results[i]<- sampledpop<-c(rep(1, 6000), rep(0, 4000))


nTrials <- 500
n <- 1000
results <- matrix(data=NA, ncol = nTrials, nrow = n)
Y<-matrix(data=NA, ncol=nTrials, nrow=1)

for(i in 1:nTrials)
{
  sampled <- sample(x=pop, size=n, replace=TRUE)
  results[,i]<- sampled
  Y[,i]<- sum(results[,i])
}

I think this code works, but I'm worried about how to tell if the matrix is filling correctly.

Phil
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Katie Nissen
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2 Answers2

1

You can easily view objects you've saved using the view function. Link to View Function in R.

we can also put a line into our R code that halts execution until after a key stroke. Stack exchange thread covering this

Putting the two together, we can then put put two lines into a loop, one which shows us the current version of the final output, and another which pauses the loop until we continue. This will let us explore the behaviour of the loop step by step. Using one of your loops as an example:

for(i in 1:nTrials)
{
  sampled <- sample(x=pop, size=n, replace=TRUE)
  results[,i]<- sampled
  Y[,i]<- sum(results[,i])
  View(Y)
  readline(prompt="Press [enter] to continue")
}

Keep in mind this will keep going for the specified amount of trials.

You could limit the amount of trials, but then you cannot be sure to get the same result, so instead we could put a break into the code. link to info about the break statement. This lets us interrupt a for loop early, assuming we are happy with how things are building up. To make the break really shine, lets pair it with some user input, you can choose if you'd like to continue or not. link for collecting user input in r

so then combing all of this we get something like:

for(i in 1:nTrials)
{
  sampled <- sample(x=pop, size=n, replace=TRUE)
  results[,i]<- sampled
  Y[,i]<- sum(results[,i])
  View(Y,)
  interrupt = readline(prompt="Enter 1 for next loop, 0 to exit: ")
  if (interrupt == 0) {break}
}

For what it's worth, your code looks perfectly fine to me so far.

Dharman
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Frithjof Herb
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0

Try this

replicate(500L, sample(c("Democrat", "Republican"), 1000L, replace = TRUE, prob = c(0.6, 0.4)), simplify = FALSE)

Or this

pop <- c(rep("Democrat", 6000L), rep("Republican", 4000L))
replicate(500L, sample(pop, 1000L), simplify = FALSE)
ekoam
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