Added filter usecase for Ansible

Ansible/README.md

@@ -13,3 +13,29 @@ ansible <hosts/groups pattern> -l <limit pattern> -m <module> -a "<module args>"
 ```
 ansible all -l localhost -m systemd -a "name=nginx state=restarted" -u test --become --ask-become-pass
 ```
+
+## Usecases
+
+### Filter numbers from a list of strings
+
+`sample.result_list` is a list of lists containing stdout output. We want to filter some numbers from this output. To do this we first filter the correct lines by using the `json_query` filter. If you need to match a specific substring, you could use `select("match", "<regex>")` in combination with the `json_query`. Next we `map` the `regex_search` filter on all lines to extract the data we need. As the `map` filter is a Python generator object, we need to convert it to a list.
+
+```yaml
+---
+
+- hosts: localhost
+
+  vars:
+    sample:
+      result_list:
+      - stdout_lines:
+        - 'line0'
+        - 'line12 (2319)'
+      - stdout_lines:
+        - 'line2'
+        - 'line12 (2320)'
+
+  tasks:
+  - debug:
+      msg: '{{ sample.results | json_query("[*].stdout_lines[1]") | map("regex_search" ,"(?<=\()\d*") | list }}'
+```