Poll of the Day > Has anyone here ever worked with R?

(+) Yeah! (+)

I need to get a random sample of 20 numbers between 1 and 50, find the mean and save it as a variable, and then repeat that process 1000 times.

I know how to do it by brute force
x1 <- Sample(1:50, 20)
m1 <- mean(x1)

But does anyone here know how I can do it without literally typing everything out a thousand times
---

I worked with R exactly one year ago. Then I decided that it was much easier to do my probability/statistics homework on an Excel sheet.

So I can't really answer your question, because I remember nothing of what I learned of the program.
---

I have to show my work in R :(

I dont want to spend a billion hours typing all of this. There must be an easier way D:
---

MrMelodramatic posted...

There must be an easier way

That sounds like something from an infomercial. In any case, I know that I'm not helping, so sorry.
---

I put my laptop away for the night but maybe I can make the code into one line... something like

m1 <- mean(sample(1:50, 20))

I dont know if it works that way, and also that doesnt solve my thousand times problem. Blah.
---

Wait, they didn't teach you loops before giving you this assignment?
---

No
---

I don't know anything about R but this sounds like something where you'd want to use a for loop, and I googled "r for loop" and it appears to be a thing. So just google it and if you can't figure it out from there I don't know what to tell you, programming probably isn't your thing

Yeah, you should just close the door to an entire career path because you're having trouble with this one homework problem /sarcasm

-write it out once and copy the line
-paste 9 times so you have 10 total, then copy that block
-repeat twice
---

Programming is most definitely not my thing, but that doesnt stop this class from being required! Ill look into the loop thing tomorrow. Thanks for the tip.
---

funkyfritter posted...

-write it out once and copy the line
-paste 9 times so you have 10 total, then copy that block
-repeat twice

But Id have to go in and manually change the variable names
---

Looks like R supports for loops just fine:

https://www.datacamp.com/community/tutorials/tutorial-on-loops-in-r

# Create a vector filled with random normal values
u1 <- rnorm(30)
print("This loop calculates the square of the first 10 elements of vector u1")

# Initialize `usq`
usq <- 0

for(i in 1:10) {
# i-th element of `u1` squared into `i`-th position of `usq`
usq[i] <- u1[i]*u1[i]
print(usq[i])
}

print(i)

It should be simple enough to modify that example to what you need.
---

Quick way:

j = rep(NA, 1000)
for (i in 1:1000) {
j[i] = 10
}

j is a vector with 1000 entries, and it starts with all of them being garbage (NA). Then inside the for loop it populates all entries of j with the number 10.

You would want to change the line inside the loop to something like j[i] = mean(sample(1:50, 20))

Then, if you wanted to output the mean of the 135th sample you took, you just type j[135] to see what number that entry has.
---

Okay, so

for (i in 1:1000) {
m[i] = mean(sample(1:50, 20))
}

looks like it's working. I don't know what

jramirez23 posted...

j = rep(NA, 1000)

this line is supposed to do for me
---

thought this was going to be about the "r" word
---

I've worked with many Rs before
---

Just put the numbers in a mathulator ya dingus
---