# Array.join for nested arrays **URL:** \ **Category:** ruby-talk\ **Created:** [28 June 2007 18:40 UTC](https://rubytalk.org/t/array-join-for-nested-arrays/38710 "2007-06-28T18:40:09Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![fu1](https://avatars.discourse-cdn.com/v4/letter/f/4da419/32.png) [@fu1](https://rubytalk.org/u/fu1)\ **Post date:** [28 June 2007 18:40 UTC](https://rubytalk.org/t/array-join-for-nested-arrays/38710/1 "2007-06-28T18:40:09Z")
Doing arr = [1, [2, [3, 4], 5], 6] arr.join(',') in Ruby 1.8.6 produces the following string: 1,2,3,4,5,6 Looking at the docs (e.g. [http://www.noobkit.com/ruby-array-join](http://www.noobkit.com/ruby-array-join)), Array.join should work as following: "Returns a string created by converting each element of the array to a string, separated by sep." Doing the following: arr.each do |e|    puts e.to\_s end produces: 1 2345 6 Thus, arr.join(',') should be: 1, 2345, 6 Am I missing something? How can I do the above? ---
**Author:** ![Martin\_DeMello](https://avatars.discourse-cdn.com/v4/letter/m/f17d59/32.png) [@Martin\_DeMello](https://rubytalk.org/u/Martin_DeMello)\ **Post date:** [28 June 2007 19:18 UTC](https://rubytalk.org/t/array-join-for-nested-arrays/38710/2 "2007-06-28T19:18:18Z")
Here's the most straightforward way: arr = [1, [2, [3, 4], 5], 6] a = "" arr.each {|i| a \<\< i.to\_s \<\< ","} a.chop! martin > **···** > > On 6/29/07, freeunli@yahoo.com \ wrote: > > > Thus, arr.join(',') should be: > > > > 1, 2345, 6 > > > > Am I missing something? How can I do the above? ---
**Author:** ![fu1](https://avatars.discourse-cdn.com/v4/letter/f/4da419/32.png) [@fu1](https://rubytalk.org/u/fu1)\ **Post date:** [28 June 2007 19:50 UTC](https://rubytalk.org/t/array-join-for-nested-arrays/38710/3 "2007-06-28T19:50:10Z")
Martin, thanks! Should the behavior of "join" be like this or the docs are wrong? ---
**Author:** ![Forum](https://avatars.discourse-cdn.com/v4/letter/f/43a26b/32.png) [@Forum](https://rubytalk.org/u/Forum)\ **Post date:** [28 June 2007 20:29 UTC](https://rubytalk.org/t/array-join-for-nested-arrays/38710/4 "2007-06-28T20:29:49Z")
Very surprised about this behavior, IMHO it is wrong, at least it is inconsistent : irb(main):007:0\> a=[1,[2,[3,4],5],6] =\> [1, [2, [3, 4], 5], 6] irb(main):008:0\> a.join(",") =\> "1,2,3,4,5,6" irb(main):009:0\> b=[1,{2=\>42},{3=\>[4,5]}] =\> [1, {2=\>42}, {3=\>[4, 5]}] irb(main):010:0\> b.join(",") =\> "1,242,345" Robert > **···** > > On 6/28/07, fu \ wrote: > > > Martin, thanks! Should the behavior of "join" be like this or the docs > > are wrong? > > -- > I always knew that one day Smalltalk would replace Java. > I just didn't know it would be called Ruby > -- Kent Back ---
**Author:** ![Rob\_Biedenharn1](https://avatars.discourse-cdn.com/v4/letter/r/57b2e6/32.png) [@Rob\_Biedenharn1](https://rubytalk.org/u/Rob_Biedenharn1)\ **Post date:** [28 June 2007 22:24 UTC](https://rubytalk.org/t/array-join-for-nested-arrays/38710/5 "2007-06-28T22:24:46Z")
Have you look at how Array#to\_s is described as returning Array#join (the only difference being that to\_s doesn't accept an argument and the default value of the separator is $,)? irb(main):001:0\> a = [1,[2,[3,4],5],6] =\> [1, [2, [3, 4], 5], 6] irb(main):002:0\> a.to\_s =\> "123456" irb(main):003:0\> a.join(',') =\> "1,2,3,4,5,6" irb(main):004:0\> $, = '-' =\> "-" irb(main):005:0\> a.to\_s =\> "1-2-3-4-5-6" irb(main):006:0\> a.join =\> "1-2-3-4-5-6" irb(main):007:0\> a.join(',') =\> "1,2,3,4,5,6" Hmm, what about that one with the hash for an element? (Remember, $, is still redefined to '-') irb(main):008:0\> b=[1,{2=\>42},{3=\>[4,5]}] =\> [1, {2=\>42}, {3=\>[4, 5]}] irb(main):009:0\> b.to\_s =\> "1-2-42-3-4-5" irb(main):010:0\> b.join(',') =\> "1,2-42,3-4-5" Hash#to\_s first converts to an array of [key,value] pairs and then converts that to a string using Array#join with the default separator. It seems that the use of "default" here, means the $, from Array#join(separator=$,), not the argument given to b.join OK, one more: irb(main):011:0\> b.last[4]=6 =\> 6 irb(main):012:0\> b =\> [1, {2=\>42}, {3=\>[4, 5], 4=\>6}] irb(main):013:0\> b.join(',') =\> "1,2-42,3-4-5-4-6" Possibly unexpected, but I don't see it as inconsistent. -Rob Rob Biedenharn [http://agileconsultingllc.com](http://agileconsultingllc.com) Rob@AgileConsultingLLC.com > **···** > > On Jun 28, 2007, at 4:29 PM, Robert Dober wrote: > > > On 6/28/07, fu \ wrote: > > > > > Martin, thanks! Should the behavior of "join" be like this or the docs > > > are wrong? > > > > Very surprised about this behavior, IMHO it is wrong, at least it is > > inconsistent : > > > > irb(main):007:0\> a=[1,[2,[3,4],5],6] > > =\> [1, [2, [3, 4], 5], 6] > > irb(main):008:0\> a.join(",") > > =\> "1,2,3,4,5,6" > > irb(main):009:0\> b=[1,{2=\>42},{3=\>[4,5]}] > > =\> [1, {2=\>42}, {3=\>[4, 5]}] > > irb(main):010:0\> b.join(",") > > =\> "1,242,345" > > > > Robert > > -- > > I always knew that one day Smalltalk would replace Java. > > I just didn't know it would be called Ruby > > -- Kent Back ---
**Author:** ![Giles\_Bowkett](https://avatars.discourse-cdn.com/v4/letter/g/96bed5/32.png) [@Giles\_Bowkett](https://rubytalk.org/u/Giles_Bowkett)\ **Post date:** [28 June 2007 22:47 UTC](https://rubytalk.org/t/array-join-for-nested-arrays/38710/6 "2007-06-28T22:47:30Z")
> I always knew that one day Smalltalk would replace Java. > I just didn't know it would be called Ruby > -- Kent Back It's Kent Beck, isn't it? Cool quote btw. > **···** > > -- > Giles Bowkett > > Blog: [http://gilesbowkett.blogspot.com](http://gilesbowkett.blogspot.com) > Portfolio: [http://www.gilesgoatboy.org](http://www.gilesgoatboy.org) ---
**Author:** ![Forum](https://avatars.discourse-cdn.com/v4/letter/f/43a26b/32.png) [@Forum](https://rubytalk.org/u/Forum)\ **Post date:** [29 June 2007 04:45 UTC](https://rubytalk.org/t/array-join-for-nested-arrays/38710/7 "2007-06-29T04:45:43Z")
> \> I always knew that one day Smalltalk would replace Java. > \> I just didn't know it would be called Ruby > \> -- Kent Back > > It's Kent Beck, isn't it? > > Cool quote btw. > > -- > Giles Bowkett > > Blog: [http://gilesbowkett.blogspot.com](http://gilesbowkett.blogspot.com) > Portfolio: [http://www.gilesgoatboy.org](http://www.gilesgoatboy.org) It's Kent, AFAIR Rick got confirmation from Kent himself. I recently attributed it to Alain Kay, Rick shook a friendly forefinger at me and I felt so bad to decide to change my sig. I have seen it before on this list though 😉 BTW Giles I do not remember any mention of the $, change in the doc, but agreed that would make it consistent, it is therefore a good way to look at that behavior without too much surprise. Cheers R. > **···** > > - ---
**Author:** ![Giles\_Bowkett](https://avatars.discourse-cdn.com/v4/letter/g/96bed5/32.png) [@Giles\_Bowkett](https://rubytalk.org/u/Giles_Bowkett)\ **Post date:** [29 June 2007 17:52 UTC](https://rubytalk.org/t/array-join-for-nested-arrays/38710/8 "2007-06-29T17:52:41Z")
> \> \> I always knew that one day Smalltalk would replace Java. > \> \> I just didn't know it would be called Ruby > \> \> -- Kent Back > \> > \> It's Kent Beck, isn't it? > \> > \> Cool quote btw. > It's Kent, AFAIR Rick got confirmation from Kent himself. Sorry, no, I mean Beck not Back. > I recently attributed it to Alain Kay, Rick shook a friendly > forefinger at me and I felt so bad to decide to change my sig. I have > seen it before on this list though 😉 Definitely an awesome quote. > BTW Giles I do not remember any mention of the $, change in the doc, > but agreed that would make it consistent, it is therefore a good way > to look at that behavior without too much surprise. Hmm. I don't remember saying what you're agreeing with me about, but hey, obviously I must have been right. > **···** > > -- > Giles Bowkett > > Blog: [http://gilesbowkett.blogspot.com](http://gilesbowkett.blogspot.com) > Portfolio: [http://www.gilesgoatboy.org](http://www.gilesgoatboy.org) ---
**Author:** ![Forum](https://avatars.discourse-cdn.com/v4/letter/f/43a26b/32.png) [@Forum](https://rubytalk.org/u/Forum)\ **Post date:** [29 June 2007 19:09 UTC](https://rubytalk.org/t/array-join-for-nested-arrays/38710/9 "2007-06-29T19:09:48Z")
> \> \> \> I always knew that one day Smalltalk would replace Java. > \> \> \> I just didn't know it would be called Ruby > \> \> \> -- Kent Back > \> \> > \> \> It's Kent Beck, isn't it? > \> \> > \> \> Cool quote btw. > > \> It's Kent, AFAIR Rick got confirmation from Kent himself. > > Sorry, no, I mean Beck not Back. I hereby declare myself an Agghead!!!! Thx Giles, quote corrected, I can only hope that Kent is \*not\* reading this list!!! > Hmm. I don't remember saying what you're agreeing with me about, but > hey, obviously I must have been right. Quite obviously 😉 > **···** > > On 6/29/07, Giles Bowkett \ wrote: > > -- > I always knew that one day Smalltalk would replace Java. > I just didn't know it would be called Ruby > -- Kent Beck