Skip index in array.each_with_index loop

Rails
1

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

2

Use the next statement.

–
Dheeraj K.

3

On Thursday, 23 May 2013 11:24:36 UTC+2, Ruby-Forum.com User wrote:

if i % 10 == 0
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

4

use next if (i % 10 != 0)

–
Dheeraj K.

5

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.

6

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

7

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,

8

On 23 May 2013 13:52, jsnark [email protected] 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

9

On 2013-May-23, at 05:24 , Ajit T. wrote:

puts “#{x} at #{i}”
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]]