[R] Need help in R

[Avi Gross]

There can be people doing homework for a course and as noted, the normal
expectation is to use the resources provided including classroom instruction
(or the often ZOOM or recordings) as well as textbooks.

Forums like this are not a substitute and some nice people will sometimes
volunteer not to do homework but help someone a bit such as asking them to
think about the problem, what data structures or loops might be needed OR
help them understand an error message or after seeing their attempts, point
out a subtle flaw.

There are some who are teaching themselves and are not being graded but are
trying little project to learn. But again, it is best they learn for
themselves and not be handed an answer.

Some mailing lists have rules and perhaps might answer someone more if it is
WORK question like how to fine tune a graph after they have most of it
working.

So, I am looking at the follow-up below with a jaundiced eye as I just saw
something similar enough being asked on a Python board. 

The first question strikes me as odd because it contains a completely
un-necessary looking part. 

> > ### Question 1
> > Create a variable containing a sequence of numbers from 1 to 100:
> >
> > Iterate over the variables and print those numbers which are prime.

You do not really need to create a sequence and then again loop over the
same sequence. The following code is shown:

n= seq(1,100)

for (j in n:100) {

Well, the look could have been using n directly or using 1:100 but uses
nonsense. To say n:100 requires n to be an integer, not some kind of
sequence or vector. And why go to 200 in any case? 

The rest gets worse and worse with oddities like using just letters of the
alphabet without meanings as variables, using integers like "f = 1" rather
than Booleans for such flags, and using the "=" operator rather than the
more accepted "<-" operator. The loop uses variable j then ignores it and
keeps manipulating i. 

Someone wanting help might want to let people know what the algorithm is
supposed to do. 

I won't try to guess and certainly won't supply a valid solution here!

-----Original Message-----
From: R-help <r-help-bounces using r-project.org> On Behalf Of Anas Jamshed
Sent: Tuesday, October 26, 2021 4:39 PM
To: Rolf Turner <r.turner using auckland.ac.nz>
Cc: R-help Mailing List <r-help using r-project.org>
Subject: Re: [R] Need help in R

Its not homework . Basically i want to get easy solution:
I am trying this for ist problem:

n= seq(1,100)

for (j in n:100) {
      f = 1
      i = 2
      n = j
      while (i <= n / 2) {
        if (n %% i == 0) {
          f = 0
          break
        }
        i = i + 1
      }
      if (f == 1) {
        print(paste("Number is prime :", n))
      }
    }

On Wed, Oct 27, 2021 at 1:35 AM Rolf Turner <r.turner using auckland.ac.nz> wrote:

>
> On Wed, 27 Oct 2021 01:09:50 +0500
> Anas Jamshed <anasjamshed1994 using gmail.com> wrote:
>
> > I need help to these questions
> >
> > ### Question 1
> > Create a variable containing a sequence of numbers from 1 to 100:
> >
> > Iterate over the variables and print those numbers which are prime.
> >
> >
> > ### Question 2
> > Create a matrix of size 3x3 called mat_1:
> >
> >  Iterate over all the values one by one and print the element as 
> > well as the position in the matrix (row, col)
>
> You really should do your own homework.
>
> cheers,
>
> Rolf Turner
>
> --
> Honorary Research Fellow
> Department of Statistics
> University of Auckland
> Phone: +64-9-373-7599 ext. 88276
>
>

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