This should be called how not to write a loop in R.

how to write such loop in R.

In The Loop

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  • In this short tutorial you got acquainted with the for loop in R. While the usage of loops in general should be avoided in R, it still remains valuable to have this knowledge in your skillset. It helps you understand underlying principles, and when prototyping a loop solution is easy to code and read. In case you want to learn more on loops, you can always check .

    A statement is used inside a loop to stop the iterations and flow the control outside of the loop. In a nested looping situation, where there is a loop inside another loop, this statement exits from the innermost loop that is being evaluated.

  • Especially for programmers that come to from other languages, R sometimes gets dinged about the speed of its loops. But a lot of the time, where you might have needed an iterative loop in another language to solve a specific task, you don't need a loop in R at all. Often, there's a pre-build function to accomplish the specific task at hand. Other times, you can use the implicit iteration of vector or matrix operations, which is much faster than using an explicit loop. And in other cases, you can use some of R's other looping constructs (like and , for example) to achieve a similar goal more elegantly.

    Basically, when it comes to looping in R, it's often best to think beyond the basic for loop. from Yihui Xie explains this point well: students, when asked to code an iterative task in R, often turned to a loop when another method would have required less code and run faster. The alternate formulations makes for an educational example for all R programmers, not just students.

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    Can someone tell me what is wrong with this if-else loop in R? I frequently can't get if-else loops to work. I get an error:

    if(match('SubjResponse',names(data))==NA) {
        observed <- data$subjresponse1="" }="" else="" {="" observed=""><- data$subjresponse="" }="">

    Note that data is a data frame.

    The error is

    Error in if (match("SubjResponse", names(data)) == NA) { : 
      missing value where TRUE/FALSE needed
    
    share|improve this question

  • Hi, it's my first time to write a loop with R for my homework. This loop is part of the function. I wanna assign values for hll according to panel [ii,1]=pp. I didn't get any error message in this part. but then when I further calculate another stuff with hll, the function can't return. I think it must be some problem in my loop. Probably something stupid or easy. But I tried to look for previous posts in forum and read R language help. But none can help.. Thanks!



    for (ii in 1:100){
            for (pp in 1:pp+1){
                    for (rr in 1:rr+1){
                            if (panel[ii,1]!=pp)
                            {
                            hll(pp,1)=ColSums(lselb1(rr:ii-1,1))
                            hll(pp,2)=ColSums(lselb2(rr:ii-1,1))
                            rr=ii
                            pp=pp+1
                            }
                            else
                            {
                            hll(pp,1)=ColSums(lselb1(rr:ii,1))
                            hll(pp,2)=ColSums(lselb2(rr:ii,1))
                            rr=ii
                            pp=pp+1}
                            }
                            }}}


    in fact I have the corresponding Gauss code here. But I really don't know how to write such loop in R.

    rr=1;
    ii=1;
    pp=1;
    do until ii==n+1;
            if pan[ii,1] ne pp;
                    hll[pp,1]=sumc(lselb1[rr:ii-1,1]);
                    hll[pp,2]=sumc(lselb2[rr:ii-1,1]);
                    rr=ii;
                    pp=pp+1;
            endif;
            if ii==n;
                    hll[pp,1]=sumc(lselb1[rr:ii,1]);
                    hll[pp,2]=sumc(lselb2[rr:ii,1]);
                    rr=ii;
                    pp=pp+1;
            endif;
            ii=ii+1;
    endo;

    Learn about and how to use For loops in R.

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    halc - Legend of Zelda: The Wind Waker 'First Time on Outset'
    from

How to use the sum function in a for loop in R? - Stack Overflow

There may be no R topic that is more controversial than the humble for-loop. And, to top it off, good help is hard to find. I was astounded by the lack of useful posts when I googled “for loops in R” (the top return linked to a page that did not exist). In fact, even searching for help within R is not easy and not even that helpful when successful ( won’t get you anywhere. will get you the help page but it is by no means exhaustive.) So, at the request of Sam, a faithful reader of the Paleocave blog, I’m going to throw my hat into the ring and brace myself for the potential onslaught of internet troll wrath.