title: create a new column that is a count of a filtered group
body: <p>I have created a column in my Power BI to calculate the distinct count of TID by Attribute using the formula below and this works </p>
  
  <pre><code>ATTRIBUTE_TID_COUNT = CALCULATE(DISTINCTCOUNT('Customer Attributes'[Attribute]) ,
                        ALLEXCEPT('Customer Attributes', 'Customer Attributes'[TID])) 
  </code></pre>
  
  <p>I need to add a filter where the <code>'Customer Attributes'[Attribute Type] = "Identifier"</code></p>
  
  <p>but I do not know how to add this filter to the column any help would be appreciated.</p>