Getting unique values from Smart Map addresses

Question

Using the following filter will return all the entries for 'CA'.

{% set params = {
    filter: {
        state: 'CA'
    }
} %}

{% set meetings = craft.entries.address(params) %}

Let's say that I get 10 returns for 'CA':

Los Angeles
Los Angeles
Los Angeles
San Diego
San Diego
San Diego
San Diego
San Diego
San Diego
Modesto

How would I go about one getting 3 results returned for each unique value for City? I only want to list each city once rather than 3 Los Angeles, 16 San Diego's and 1 Modesto. Like this:

Los Angeles
San Diego
Modesto

It could also be helpful to have them like this:

3 Los Angeles
6 San Diego
1 Modesto

I am building a navigation by state with a list of cities under each state. To look like this:

CA
   Los Angeles
   San Diego
   Modesto
KS
   Wichita
   Kansas City

Answer 1

You'd actually need to retrieve all of the entries to count them in this way. Once you've got the complete collection, it would simply be a matter of looping through them and adding everything up.

1. Get all entries in California.

{% set params = {
    filter: {
        state: 'CA'
    }
} %}

{% set meetings = craft.entries.address(params).all() %}

2. Loop through those entries. Build a new array based on the results.

{% set stateMeetings = {} %}
    
{% for meeting in meetings %}

    {% set city = meeting.address.city %}

    {% if stateMeetings[city] is defined %}
        {% set cityTotal = stateMeetings[city] + 1 %}
    {% else %}
        {% set cityTotal = 1 %}
    {% endif %}

    {% set stateMeetings = stateMeetings|merge{(city):cityTotal} %}

{% endfor %}

3. By the time that's all done, you'll have a neat associative array, where each key is a different city, and the value of each represents how many times it was found.

{
    "Los Angeles": 3,
    "San Diego": 6,
    "Modesto": 1,
}

You'll definitely want to cache all of that... it'll be a pretty expensive process.

To be honest, I'd actually recommend doing all of this work in a plugin (or module). It's a fairly easy thing to achieve with a template hook. This kind of heavy merging is ill-fitted for Twig, but much simpler in PHP.