# with\_items and array concatenation? **URL:** \ **Category:** Ansible Project\ **Created:** [June 4, 2014, 9:47pm UTC](https://forum.ansible.com/t/with-items-and-array-concatenation/15403 "2014-06-04T21:47:38Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Dimon](https://avatars.discourse-cdn.com/v4/letter/d/eb8c5e/32.png) [@Dimon](https://forum.ansible.com/u/Dimon)\ **Post date:** [June 4, 2014, 9:47pm UTC](https://forum.ansible.com/t/with-items-and-array-concatenation/15403/1 "2014-06-04T21:47:38Z")
Hi, I’ve got a usecase where I’d like to iterate over several servers based on groups, so task looks like: - name: group A & B shell: echo {{ item }} \>\> /tmp/log with\_items: - groups[“A”] - groups[“B”] so what I get in /tmp/log is: groups[‘A’] groups[‘B’] Now, eliminating either group I can get: - name: group A shell: echo {{ item }} \>\> /tmp/log with\_items: groups[“A”] I get proper result. I’m pretty certain I’ve seen this topic come up recently but can’t find it anymore. Any pointers (including links to other topics) are welcome. P.S. for bonus points - can I do set-like concatenation - i.e. eliminate duplicates? ---
**Author:** ![adam2](https://avatars.discourse-cdn.com/v4/letter/a/ecae2f/32.png) [@adam2](https://forum.ansible.com/u/adam2)\ **Post date:** [June 4, 2014, 9:50pm UTC](https://forum.ansible.com/t/with-items-and-array-concatenation/15403/2 "2014-06-04T21:50:30Z")
ansible uses jinga2. Look up that syntax. Then, off the top of my head, may not be exactly right, but: groups["A"].concat(groups["B"]) | set | list Some of that is python syntax(the contact, check jinga2 and python docs), and the |set|list is jinga2. ---
**Author:** ![Dimon](https://avatars.discourse-cdn.com/v4/letter/d/eb8c5e/32.png) [@Dimon](https://forum.ansible.com/u/Dimon)\ **Post date:** [June 4, 2014, 9:57pm UTC](https://forum.ansible.com/t/with-items-and-array-concatenation/15403/3 "2014-06-04T21:57:15Z")
nice try - but no dice: fatal: [192.168.0.138] =\> with\_items expects a list or a set FATAL: all hosts have already failed – aborting I even played a bit and checked python syntax making it: groups[‘A’].extend(groups[‘B’])|set with or without last “list” filter with original syntax or with my “correction” it fails as per above. -vvvv doesn’t help much to pinpoint where the problem is. ---
**Author:** ![Dimon](https://avatars.discourse-cdn.com/v4/letter/d/eb8c5e/32.png) [@Dimon](https://forum.ansible.com/u/Dimon)\ **Post date:** [June 4, 2014, 10:01pm UTC](https://forum.ansible.com/t/with-items-and-array-concatenation/15403/4 "2014-06-04T22:01:50Z")
thanks to your hint I’m one step closer: - name: group A & B shell: echo {{ item }} \>\> /tmp/log with\_items: groups[“A”] + groups[“B”] however I still can’t figure out how to make a “set” out of the result. ---
**Author:** ![sivel](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/sivel/32/1198_2.png) [@sivel](https://forum.ansible.com/u/sivel)\ **Post date:** [June 4, 2014, 10:02pm UTC](https://forum.ansible.com/t/with-items-and-array-concatenation/15403/5 "2014-06-04T22:02:22Z")
You might want to take a look at the ‘set’ filters provided by ansible at [http://docs.ansible.com/playbooks\_variables.html#set-theory-filters](http://docs.ansible.com/playbooks_variables.html#set-theory-filters) I imagine something like: with\_items: groups[‘A’]|union(groups[‘B’])|unique would work. I doubt it is needed, but you might have to add |list onto the end of that. I think jinja2 addition may also work: with\_items: (groups[‘A’] + groups[‘B’])|unique ---
**Author:** ![Dimon](https://avatars.discourse-cdn.com/v4/letter/d/eb8c5e/32.png) [@Dimon](https://forum.ansible.com/u/Dimon)\ **Post date:** [June 4, 2014, 10:17pm UTC](https://forum.ansible.com/t/with-items-and-array-concatenation/15403/6 "2014-06-04T22:17:04Z")
Thanks Matt and Adam! Winning combination turned out to be: ( groups[‘A’]+groups[‘B’] ) | unique I do like how simple it looks vs ( groups[‘A’]|union (groups[‘B’]))| unique since in my case I have more groups to add and it is very simple with “+” and less error-prone. ---
**Author:** ![C\_Morgan\_Hamill](https://avatars.discourse-cdn.com/v4/letter/c/ebca7d/32.png) [@C\_Morgan\_Hamill](https://forum.ansible.com/u/C_Morgan_Hamill)\ **Post date:** [June 5, 2014, 2:26pm UTC](https://forum.ansible.com/t/with-items-and-array-concatenation/15403/7 "2014-06-05T14:26:16Z")
Excerpts from Dmitry Makovey's message of 2014-06-04 18:17:04 -0400: > Winning combination turned out to be: > > ( groups['A']+groups['B'] ) | unique > > I do like how simple it looks vs > > ( groups['A']|union (groups['B']))| unique Just FYI, the 'unique filter in the latter form is redundant; this should work fine:     groups['A']|union(groups['B') Sets, by definition, have no duplicate items. ---
**Author:** ![Michael\_DeHaan1](https://avatars.discourse-cdn.com/v4/letter/m/5e9695/32.png) [@Michael\_DeHaan1](https://forum.ansible.com/u/Michael_DeHaan1)\ **Post date:** [June 6, 2014, 12:36pm UTC](https://forum.ansible.com/t/with-items-and-array-concatenation/15403/8 "2014-06-06T12:36:41Z")
The first problem here is not about sets or unions or anything. The issue is with\_items wants a single list to walk over, not a list of two lists. So with\_items: variable\_ame works as does with\_items: - dog - cat - fish With hard coded strings But if you want to walk two lists, that’s “with\_nested”. Here, though you do want to add them together. I just wanted to mention why you were seeing “groups[“A”]” literally in the first logfile above.