Clash Royale CLAN TAG#URR8PPP

Getting R to skip certain index values with the help of if statements, within while loops

I have been through multiple R-while-if questions and I didn't find a similar one. Please guide me to the answer if it has been asked.

So I have a vector V of N=200 entries of number 0. Every entry signifies a "bin". I skip the first 3 bins, for separate reasons. Now for i= 3:N number of bins, I use a while loop.

N=200

0

i= 3:N

i

0

1

0

i

V

if the random number is greater than the numerical value, I simply consider the next i.

i

Here's the code I am running:

N = 200
Time <- rep(0, N)
Time <- replace(Time, 3, 1)
i = 5
while (i <= N)
p <- runif(1)
if(p < 0.66)
i= i+ 2; replace(Time, i, 1)
else
i <- i+1




I am not very good at R, and this is the combination I have been trying to use, to get R to do what I want, but it's clearly not working. I might be missing something obvious.

1 Answer
1

Your problem is that most functions in R do not modify objects they are applied to. Instead, they return a modified version of the original object which you have to assign, either to a new object, or to the original one (update it).

R

So instead of just running replace(Time, i, 1) (which does not update the Time vector), you need to assign the modified version back to Time like this:

replace(Time, i, 1)

Time

Time

Time <- replace(Time, i, 1)


or, better yet, use square bracket notation to update directly:

Time[i] <- 1


Moreover, you need to update vector Time, Time <- replace(Time, i, 1), before you update your index i, i = i + 2. If you want to apply your loop only to i > 3, then you need to set i = 4. Finally, in case runif(1) < 0.66, if you want to skip the next two entries in Time, you should update i as i <- i + 3.

Time

Time <- replace(Time, i, 1)

i

i = i + 2

i > 3

i = 4

runif(1) < 0.66

Time

i

i <- i + 3

To summarise, you should modify your loop as follows:

N = 200
Time <- rep(0, N)
Time[3] <- 1
i <- 4

while (i <= N)
p <- runif(1)
if(p < 0.66)
Time[i] <- 1
i <- i + 3
else
i <- i+1




replace

subset

replace

[<-

replace

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