title: How to map scalar twig filter to array
body: <p>I have a simple array of floats. And I need to show it as comma separated string.</p>
  
  <pre><code>{{ arr|join(', ') }}
  </code></pre>
  
  <p>is bad solution because of excessive insignificant accuracy.</p>
  
  <pre><code>{% for val in arr %}
      {{val|number_format(2)}},
  {% endfor %}
  </code></pre>
  
  <p>is bad because of extra comma at the end.</p>
  
  <p>I would like to do something like this:</p>
  
  <pre><code>{{ arr|map(number_format(3))|join(', ') }}
  </code></pre>
  
  <p>but I have not found filter <code>map</code> or similar filter it Twig. 
  Аnd I don't know how to implement such filter.</p>