R locate the iterator - r

I have a simple loop
for(z in 1:length(x)){
country=region_names[z]
//paste("xyz",country)//
....
}
Now, after the loop is finished, z will have the value equal to the length of x.
Now, I need to find a way to add an iterator.
Supposedly, when it is at the second loop, iterator=2, it will show "xyzUSA".
Supposedly, when it is at the third loop, iterator=3, it will show "xyzFrance"
My problem is, I don't need to show them all at once, but when the iterator is triggered, the program knows what the value of iterator is, and shows the corresponding country.
Now, how can I build an iterator like this?
Any help is appreciated


To all people who cannot understand my question, I myself figured it out.
It was an issue of lazy evaluation. It can be solved by using
force()
Sorry about the confusion, your help is appreciated.

Related

Write a loop to divide last value in y and first value in x and so on for #whole vector

I'm unsure how to do this. If possible a walkthrough on this would be greatly appreciated! Just started a class that uses R and find somethings to be very complicated.
Thanks!
I have tried to just write simple types of loops but not sure how to tie in all of the functions I need to do.

How to make for loop for expected returns of this dataset?

I am trying to make a vector with the expected returns of the dataset that I have but I do not know how to finish the segment off. I have a little bit of what we started with since he did not give us any more information other than this to do for loops and I am very confused. If you have any suggestions on what needs to go into the mean parentheses that would be greatly appreciated.
for (ii in 2:31)
{
expectedreturn[ii]=mean()
}

For loop setup with multiple parameters in R

I'm trying to figure out how to get a for loop setup in R when I want it to run two or more parameters at once. Below I have posted a sample code where I am able to get the code to run and fill a matrix table with two values. In the 2nd line of the for loop I have
R<-ARMA.var(length(x_global_sample),ar=c(tt[i],-.7))
And what I would like to do is replace the -.7 with another tt[i], example below, so that my for loop would run through the values starting at (-1,-1), then it would be as follows (-1,-.99),
(-1,-.98),...,(1,.98),(1,.99),(1,1) where the result matrix would then be populated by the output of Q and sigma.
R<-ARMA.var(length(x_global_sample),ar=c(tt[i],tt[i]))
or something similar to
R<-ARMA.var(length(x_global_sample),ar=c(tt[i],ss[i]))
It may be very possible that this would be better handled by two for loops however I'm not 100% sure on how I would set that up so the first parameter would be fixed and the code would run through the sequence of the second parameter, once that would get finished the first parameter would now increase by one and fix itself at that increase until the second parameter does another run through.
I've posted some sample code down below where the ARMA.var function just comes from the ts.extend package. However, any insight into this would be great.
Thank you
tt<-seq(-1,1,0.01)
Result<-matrix(NA, nrow=length(tt)*length(tt), ncol=2)
for (i in seq_along(tt)){
R<-ARMA.var(length(x_global_sample),ar=c(tt[i],-.7))
Q<-t((y-X%*%beta_est_d))%*%solve(R)%*%(y-X%*%beta_est_d)+
lam*t(beta_est_d)%*%D%*%beta_est_d
RSS<-sum((y-X%*%solve(t(X)%*%solve(R)%*%X+lam*D)%*%t(X)%*%solve(R)%*%y)^2)
Denom<-n-sum(diag(X%*%solve(t(X)%*%solve(R)%*%X+lam*D)%*%t(X)%*%solve(R)))
sigma<-RSS/Denom
Result[i,1]<-Q
Result[i,2]<-sigma
rm(Q)
rm(R)
rm(sigma)
}
Edit: I realize that what I have posted above is quite unclear so to simplify things consider the following code,
x<-seq(1,20,1)
y<-seq(1,20,2)
Result<-matrix(NA, nrow=length(x)*length(y), ncol=2)
for(i in seq_along(x)){
z1<-x[i]+y[i]
z2<-z1+y[i]
Result[i,1]<-z1
Result[i,2]<-z2
}
So the results table would appear as follow as the following rows,
Row1: 1+1=2, 2+1=3
Row2: 1+3=4, 4+3=7
Row3: 1+5=6, 6+5=11
Row4: 1+7=8, 8+7=15
And this pattern would continue with x staying fixed until the last value of y is reached, then x would start at 2 and cycle through the calculations of y to the point where my last row is as,
RowN: 20+19=39, 39+19=58.
So I just want to know if is there a way to do it in one loop or if is it easier to run it as 2 loops.
I hope this is clearer as to what my question was asking, and I realize this is not the optimal way to do this, however for now it is just for testing purposes to see how long my initial process takes so that it can be streamlined down the road.
Thank you

Julia JuMP - array index which is an index of another array

I have to solve a problem with permutations. The function takes vector a with n elements as a parameter. I declare b as #variable - there should be the permutation 1:n that gives the best result after finding the solution of a problem.
The error appears when I want to create #constraint. I have to use a[b[1]], so it takes the first element from vector which is a variable. It gives my error, that I can't use type VariableRef as a index of an array. But how can I get around this when I have to use it?

I sounds as if you have two optimisation problems one of which is an integer programming problem. You might think about separating the two.
(Sorry for not writing a comment, my reputation is still too low ;-) )

My looping code in prolog won't work with the rest of my code

I am working on a school assignment where I have to find the smallest hitting set of a list of lists. Right now I am working on finding all the hitting sets before I narrow it down to the smallest one. I implemented a way for my code to find out if two lists have at least one number in common. To my knowledge it works as intended by itself but whenever I try to connect it to the main part of my code it won't work or runs indefinitely. Any help would be appreciated.
Minimal, Reproducible Example:
This code has been made in a way that it will return true anytime a two arrays have at least one number that intersects between the two. I have tested this code and to my knowledge it works as intended. The first result back is always correct when I tested it.
checkForIntersection([],[]):- false.
checkForIntersection([Head|Tail],[Head2|Tail2]):-
Head = Head2;
checkForIntersection(Tail,[Head2|Tail2]);
checkForIntersection([Head|Tail],Tail2).
This part of the code is where I believe an error occurs. I have an AnswerSet as the list that I want to check for intersections. The [Check|NextCheck] is a list of lists and I want to check each of them against the AnswerSet. I loop through it until the [Check|NextCheck] is empty. The issue is that when I call it the results I get is an infinite amount of trues even if the answer should be false.
loopThroughListOfLists(CheckListsAgenstThisList,[]).
loopThroughListOfLists(CheckListsAgenstThisList,[ListToCheck|NextListToCheck]):-
checkForIntersection(ListToCheck,CheckListsAgenstThisList),
loopThroughListOfLists(CheckListsAgenstThisList,NextListToCheck).
loopCheck([3],[[1], [1], [3], [4], [4]]). This is one of the cases I used to test my code with. Instead of returning false it returns an infinite amount of trues whenever I test it.
Thank you so much for reading, I am sorry if this is a really stupid question, I am really struggling with Prolog.

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