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Ajit Teli

2013-May-23 09:24 UTC

Skip index in array.each_with_index loop

Can anyone help me on how to skip index in ARRAY.each_with_index loop?

Please look at below case:

In a ARRAY.each_with_index loop, I would like increase the index by 10
whenever a condition is met.

arr is array of numbers from 0 to 50
arr.each_with_index do |x,i|
  if i % 10 == 0
    puts "#{x} at #{i}"
    i = i+10  //index increased by 10
  end
end

The output should be:
10 at 10
30 at 30
50 at 50

Thanks
Ajit

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Dheeraj Kumar

2013-May-23 09:32 UTC

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Re: Skip index in array.each_with_index loop

Use the `next` statement.

http://www.tutorialspoint.com/ruby/ruby_loops.htm 

-- 
Dheeraj Kumar


On Thursday 23 May 2013 at 2:54 PM, Ajit Teli wrote:
> Can anyone help me on how to skip index in ARRAY.each_with_index loop?
> 
> Please look at below case:
> 
> In a ARRAY.each_with_index loop, I would like increase the index by 10
> whenever a condition is met.
> 
> arr is array of numbers from 0 to 50
> arr.each_with_index do |x,i|
> if i % 10 == 0
> puts "#{x} at #{i}"
> i = i+10 //index increased by 10
> end
> end
> 
> The output should be:
> 10 at 10
> 30 at 30
> 50 at 50
> 
> Thanks
> Ajit
> 
> -- 
> Posted via http://www.ruby-forum.com/.
> 
> -- 
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> 
> 

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Javix

2013-May-23 09:39 UTC

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Re: Skip index in array.each_with_index loop

On Thursday, 23 May 2013 11:24:36 UTC+2, Ruby-Forum.com User
wrote:>
> Can anyone help me on how to skip index in ARRAY.each_with_index loop? 
>
> Please look at below case: 
>
> In a ARRAY.each_with_index loop, I would like increase the index by 10 
> whenever a condition is met. 
>
> arr is array of numbers from 0 to 50 
> arr.each_with_index do |x,i| 
>   if i % 10 == 0 
>     puts "#{x} at #{i}" 
>     i = i+10  //index increased by 10 
>   end 
> end 
>
> The output should be: 
> 10 at 10 
> 30 at 30 
> 50 at 50 
>
> Thanks 
> Ajit 
>
> Could you explain it in a more clear way, "whenever a condition is
met".If you just want to select the elements that meet some condition, use one 
of the following Array methods:

keep_if <http://ruby-doc.org/core-2.0/Array.html#method-i-keep_if>
select <http://ruby-doc.org/core-2.0/Array.html#method-i-select>
reject <http://ruby-doc.org/core-2.0/Array.html#method-i-reject>
> -- 
> Posted via http://www.ruby-forum.com/. 
>
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Ajit Teli

2013-May-23 09:55 UTC

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Re: Skip index in array.each_with_index loop

Dear Dheeraj,

  Thanks for your reply.

The statement `next` will increment the index by 1. But I want to 
increment the index by 10.

Thanks,

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Dheeraj Kumar

2013-May-23 10:16 UTC

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Re: Re: Skip index in array.each_with_index loop

use `next if (i % 10 != 0)`

-- 
Dheeraj Kumar


On Thursday 23 May 2013 at 3:25 PM, Ajit Teli wrote:
> Dear Dheeraj,
> 
> Thanks for your reply.
> 
> The statement `next` will increment the index by 1. But I want to 
> increment the index by 10.
> 
> Thanks,
> 
> -- 
> Posted via http://www.ruby-forum.com/.
> 
> -- 
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> 
> 

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jsnark

2013-May-23 12:52 UTC

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Re: Skip index in array.each_with_index loop

Write a loop that generates the desired indexes and then reference arr:

(0..5).each do |j|
  i = 10*j
  puts "#{arr[i]} at #{i}"
end

Your example output does not match the code.  It does not include 0, 20, 
and 40.

On Thursday, May 23, 2013 5:24:36 AM UTC-4, Ruby-Forum.com User
wrote:>
> Can anyone help me on how to skip index in ARRAY.each_with_index loop? 
>
> Please look at below case: 
>
> In a ARRAY.each_with_index loop, I would like increase the index by 10 
> whenever a condition is met. 
>
> arr is array of numbers from 0 to 50 
> arr.each_with_index do |x,i| 
>   if i % 10 == 0 
>     puts "#{x} at #{i}" 
>     i = i+10  //index increased by 10 
>   end 
> end 
>
> The output should be: 
> 10 at 10 
> 30 at 30 
> 50 at 50 
>
> Thanks 
> Ajit 
>
> -- 
> Posted via http://www.ruby-forum.com/. 
>
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Robert Walker

2013-May-23 13:50 UTC

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Re: Skip index in array.each_with_index loop

jsnark wrote in post #1109941:> Write a loop that generates the desired indexes and then reference arr:
>
> (0..5).each do |j|
>   i = 10*j
>   puts "#{arr[i]} at #{i}"
> end
>
> Your example output does not match the code.  It does not include 0, 20,
> and 40.
# Print every 10th object
(0..50).each_slice(10) { |slice| p slice[0] }

0
10
20
30
40
50

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Rob Biedenharn

2013-May-23 16:54 UTC

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Re: Skip index in array.each_with_index loop

On 2013-May-23, at 05:24 , Ajit Teli wrote:
> Can anyone help me on how to skip index in ARRAY.each_with_index loop?
> 
> Please look at below case:
> 
> In a ARRAY.each_with_index loop, I would like increase the index by 10
> whenever a condition is met.
> 
> arr is array of numbers from 0 to 50
> arr.each_with_index do |x,i|
>  if i % 10 == 0
>    puts "#{x} at #{i}"
>    i = i+10  //index increased by 10
>  end
> end
> 
> The output should be:
> 10 at 10
> 30 at 30
> 50 at 50
> 
> Thanks
> Ajit
You need to think about what you really need to do, look at the options to use
select or reject/delete_if, or take the time to understand what next does. Of
course, you don''t seem to have even tried to run your code since your
output lacks "0 at 0".

-Rob

For example:

irb2.0.0> arr = (0..50).to_a
#2.0.0 => [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38,
39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50]
irb2.0.0>   arr.each_with_index do |element,index|
?>              next unless index % 10 == 0
irb2.0.0>     puts "#{element} at #{index}"
irb2.0.0>   end
0 at 0
10 at 10
20 at 20
30 at 30
40 at 40
50 at 50
#2.0.0 => [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38,
39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50]
irb2.0.0>   arr.each.with_index.select {|element,index| index % 10 == 0}.each
do |element,index|
?>              puts "#{element} at #{index}"
irb2.0.0>   end
0 at 0
10 at 10
20 at 20
30 at 30
40 at 40
50 at 50
#2.0.0 => [[0, 0], [10, 10], [20, 20], [30, 30], [40, 40], [50, 50]]


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Colin Law

2013-May-23 19:08 UTC

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Re: Re: Skip index in array.each_with_index loop

On 23 May 2013 13:52, jsnark <swr-I/mPKdbEGRBWk0Htik3J/w@public.gmane.org>
wrote:> Write a loop that generates the desired indexes and then reference arr:
>
> (0..5).each do |j|
>   i = 10*j
>   puts "#{arr[i]} at #{i}"
> end
>
> Your example output does not match the code.  It does not include 0, 20,
and
> 40.
I don''t think the OP wanted 20 and 40 which is why he is adding 10
rather than 9.  I suspect the example is just an example and does not
represent the actual code he wants, in particular there is likely to
be an else block, and it that which he wishes to skip.  I think the
answer to his question, however, is that there is no way to change the
index within the block in order to skip elements, so he will have to
use one of the suggestions made by others.

Colin
>
>
> On Thursday, May 23, 2013 5:24:36 AM UTC-4, Ruby-Forum.com User wrote:
>>
>> Can anyone help me on how to skip index in ARRAY.each_with_index loop?
>>
>> Please look at below case:
>>
>> In a ARRAY.each_with_index loop, I would like increase the index by 10
>> whenever a condition is met.
>>
>> arr is array of numbers from 0 to 50
>> arr.each_with_index do |x,i|
>>   if i % 10 == 0
>>     puts "#{x} at #{i}"
>>     i = i+10  //index increased by 10
>>   end
>> end
>>
>> The output should be:
>> 10 at 10
>> 30 at 30
>> 50 at 50
>>
>> Thanks
>> Ajit
>>
>> --
>> Posted via http://www.ruby-forum.com/.
>
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>
>
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Rails - May 2013 - Skip index in array.each_with_index loop

Skip index in array.each_with_index loop

Re: Skip index in array.each_with_index loop

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