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In The Loop

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I have noticed a curious thing whilst working in R

I then proceeded to use Eclipse's auto complete feature to createa for loop iterating over the ArrayList, the generated code was notgenerics friendly, it used an iterator without using generics, andcreated a cast inside the loop.

The Syntax of the for loop in several languages is below. Notice how each language captures the "semantics" of a for loop (the meaning) but each has slightly different syntaxes. The variable "i" below is always used as the loop counter. The variables, start_value,by_count,and finish_value all represent numbers. For each language and example of the code to sum the numbers from 1 to 10 is given.

How to Loop Through Values in R - For Dummies

  1. Like all loops, "for loops" execute blocks of code over and over again.

  2. The advantage to a for loop is we know exactly how many times the loop will execute before the loop starts.

  3. The Syntax of the for loop in several languages is below. Notice how each language captures the "semantics" of a for loop (the meaning) but each has slightly different syntaxes. The variable "i" below is always used as the loop counter. The variables, start_value,by_count,and finish_value all represent numbers. For each language and example of the code to sum the numbers from 1 to 10 is given.

                      
     % design pattern
     for i = start_value:by_count:finish_value
       do something
     end
    
     % example: sum numbers from 1 to 10
     total = 0;
     for i = 1 : 10
       total = total + i;
     end
                      
                    
                      
     // design pattern
     for (int i=start_value; i < finish_value;="" i="i" +="" by_count="" )="" {="" do="" something="" }="" example:="" sum="" numbers="" from="" 1="" to="" 10="" int="" total="0;" for="" (int="" i="1;" i<10;="" i++)="" {="" total="" +="i;" }="">
                    
                      
     // design pattern
     for (var  i:int = start_value; i < finish_value;="" i="i" +="" by_count="" );="" {="" do="" something="" }="" example:="" sum="" numbers="" from="" 1="" to="" 10="" var="" total:int="0;" for="" (var="" i:int="1;" i<10;="" i++)="" {="" total="total" +="" i;="" }="">
                    

R-loop - Wikipedia, the free encyclopedia

If for loops in R prove no challenge to you anymore after reading this tutorial, you might consider taking our course. This course will strengthen your knowledge of the topics in Intermediate R with a bunch of new and fun exercises. If, however, loops hold no secrets for you any longer, our course, taught by Hadley and Charlotte Wickham could interest you.

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.