text: {#
  This calculates the distance between two sets of latitude and longitude.
  The formula is from the following blog post:
  http://daynebatten.com/2015/09/latitude-longitude-distance-sql/
  
  The arguments should be float type.
  #}
  
  {% macro degrees_to_radians(degrees) -%}
      acos(-1) * {{degrees}} / 180
  {%- endmacro %}
  
  {% macro haversine_distance(lat1, lon1, lat2, lon2, unit='mi') -%}
      {{ return(adapter.dispatch('haversine_distance', packages = dbt_utils._get_utils_namespaces())(lat1,lon1,lat2,lon2,unit)) }}
  {% endmacro %}
  
  {% macro default__haversine_distance(lat1, lon1, lat2, lon2, unit='mi') -%}
  {%- if unit == 'mi' %}
      {% set conversion_rate = 1 %}
  {% elif unit == 'km' %}
      {% set conversion_rate = 1.60934 %}
  {% else %}
      {{ exceptions.raise_compiler_error("unit input must be one of 'mi' or 'km'. Got " ~ unit) }}
  {% endif %}
  
      2 * 3961 * asin(sqrt(pow((sin(radians(({{ lat2 }} - {{ lat1 }}) / 2))), 2) +
      cos(radians({{lat1}})) * cos(radians({{lat2}})) *
      pow((sin(radians(({{ lon2 }} - {{ lon1 }}) / 2))), 2))) * {{ conversion_rate }}
  
  {%- endmacro %}
  
  
  
  {% macro bigquery__haversine_distance(lat1, lon1, lat2, lon2, unit='mi') -%}
  {% set radians_lat1 = dbt_utils.degrees_to_radians(lat1) %}
  {% set radians_lat2 = dbt_utils.degrees_to_radians(lat2) %}
  {% set radians_lon1 = dbt_utils.degrees_to_radians(lon1) %}
  {% set radians_lon2 = dbt_utils.degrees_to_radians(lon2) %}
  {%- if unit == 'mi' %}
      {% set conversion_rate = 1 %}
  {% elif unit == 'km' %}
      {% set conversion_rate = 1.60934 %}
  {% else %}
      {{ exceptions.raise_compiler_error("unit input must be one of 'mi' or 'km'. Got " ~ unit) }}
  {% endif %}
      2 * 3961 * asin(sqrt(pow(sin(({{ radians_lat2 }} - {{ radians_lat1 }}) / 2), 2) +
      cos({{ radians_lat1 }}) * cos({{ radians_lat2 }}) *
      pow(sin(({{ radians_lon2 }} - {{ radians_lon1 }}) / 2), 2))) * {{ conversion_rate }}
  
  {%- endmacro %}
  
  