If you want to do some basic django calculations, you can use
django-mathfilters is simple to use for add, subtract, mul, and div
On Sat, Jul 24, 2021, 3:33 PM mab.mo...@gmail.com <mab.mobile...@gmail.com>
wrote:
> Thank you Derek for the information. For those that are having similar
> problems this is the solution that worked for me based on Derek's lead....
>
> ## METHOD 1 ##
>
> # view
>
> def position_view(request):
>
> packet_data =
> TncData.objects.exclude(lat=0).order_by('-dt_heard')[:100]
>
> # loop through query set and add new dictionary key-value pair
>
> for row in packet_data:
>
> row.distance = row.lat*row.lon # example only of calculation only
> not real
>
> return render(request, 'main/position.html',
> {'packet_data':packet_data,})
>
> # html template snippet
>
> {% for row in packet_data %}
>
> <tr class='atable'>
> <td class='atable'>{{row.callsign}}</td>
> <td class='atable'>{{row.lat|floatformat:2}} N
> {{row.lon|floatformat:2}} W </td>
> <td class='atable'
> style='text-align:right;'>{{row.distance|floatformat:1}} miles</td>
> <td class='atable'
> style='text-align:right;'>{{row.bearing|floatformat:0}} deg</td>
> <td class='atable' style='padding-left:20px;'>{{row.dt_heard|date:"D
> m/d H:i"}}</td>
> </tr>
>
> {% endfor %}
>
> ## METHOD 2 use @property in the model.py file
>
> # Put the data calculations in the model.py file
>
> class TncData(models.Model):
> callsign = models.TextField(max_length=20)
> lat = models.FloatField(null=True, blank=True, default=None)
> lon = models.FloatField(null=True, blank=True, default=None)
> path = models.TextField(max_length=250)
> message = models.TextField(max_length=250)
> dt_heard = models.DateTimeField(auto_now_add=False)
>
> def __str__(self):
> return str(self.callsign)
>
> ## HAVERSINE FORMULA
>
> @property
> def calculate_distance(self):
>
> # Variables
>
> r = 6371 # radius earth km
>
> lat_1 = radians(42.97)
> lon_1 = radians(89.77)
>
> lat_2 = radians(self.lat)
> lon_2 = radians(self.lon)
>
> dlat = lat_1 - lat_2
> dlon = lon_1 - lon_2
>
> a = sin(dlat / 2)**2 + cos(lat_1) * cos(lat_2) * sin(dlon / 2)**2
>
> c = 2 * asin(sqrt(a))
>
> distance_km = c*r
> distance = distance_km * 0.621
>
> return(distance)
>
> # html template snippet
>
> {% for row in packet_data %}
>
> <tr class='atable'>
> <td class='atable'>{{row.callsign}}</td>
> <td class='atable'>{{row.lat|floatformat:2}} N
> {{row.lon|floatformat:2}} W </td>
> <td class='atable' style='text-align:right;'>{{
> *row.calculate_distance|*floatformat:1}} miles</td>
> <td class='atable'
> style='text-align:right;'>{{row.bearing|floatformat:0}} deg</td>
> <td class='atable' style='padding-left:20px;'>{{row.dt_heard|date:"D
> m/d H:i"}}</td>
> </tr>
>
>
> {% endfor %}
>
>
> On Wednesday, July 21, 2021 at 5:01:02 PM UTC-5 mab.mo...@gmail.com wrote:
>
>> Thanks Derek. I'll give it a try
>>
>> On Wednesday, July 21, 2021 at 8:55:08 AM UTC-5 Derek wrote:
>>
>>> See:
>>> https://stackoverflow.com/questions/54412377/adding-values-to-django-queryset
>>>
>>>
>>> VIEW
>>>
>>> def position_view(request):
>>>
>>> packet_data =
>>> TncData.objects.exclude(lat=0).order_by('-dt_heard')[:100]
>>> for packet in packet_data:
>>> *# my complex math calculation*
>>> * packet.distance = "# complex math formula using packet.lat and
>>> packet.lon"*
>>>
>>> return render(
>>> request,
>>> 'main/position.html',
>>> {'packet_data': packet_data, 'distance': distance})
>>>
>>> TEMPLATE
>>>
>>> *# suggest you use a better term than "field" => maybe "record"?*
>>> {% for field in packet_data %}
>>> <tr class='atable'>
>>> <td class='atable'>{{field.callsign}}</td>
>>> <td class='atable'>{{field.lat|floatformat:2}} N
>>> {{field.lon|floatformat:2}} W </td>
>>> <td class='atable'></td>
>>> *<td class='atable'>{{field.distance}}</td>*
>>>
>>>
>>> HTH!
>>>
>>> On Tuesday, 20 July 2021 at 22:25:04 UTC+2 mab.mo...@gmail.com wrote:
>>>
>>>> Hello,
>>>>
>>>> I am trying to perform a complex math calculation from a django query
>>>> set. How can I pass the results to the template for display? Annotations
>>>> won't work since the math is not a simple sum, diff or average.
>>>>
>>>> MODEL
>>>>
>>>> class TncData(models.Model):
>>>> callsign = models.TextField(max_length=20)
>>>> lat = models.FloatField(null=True, blank=True, default=None)
>>>> lon = models.FloatField(null=True, blank=True, default=None)
>>>> path = models.TextField(max_length=250)
>>>> message = models.TextField(max_length=250)
>>>> dt_heard = models.DateTimeField(auto_now_add=False)
>>>>
>>>> def __str__(self):
>>>> return str(self.callsign)
>>>>
>>>> VIEW
>>>>
>>>> def position_view(request):
>>>>
>>>> packet_data =
>>>> TncData.objects.exclude(lat=0).order_by('-dt_heard')[:100]
>>>>
>>>> *# my complex math calculation*
>>>> * # need to do something like append distance to packet_data like
>>>> packet_data.distance*
>>>>
>>>> * distance = "# complex math formula using packet_data.lat and
>>>> packet_data.lon"*
>>>>
>>>> return render(request, 'main/position.html',
>>>> {'packet_data':packet_data,})
>>>>
>>>> TEMPLATE
>>>>
>>>> {% for field in packet_data %}
>>>>
>>>> <tr class='atable'>
>>>> <td class='atable'>{{field.callsign}}</td>
>>>> <td class='atable'>{{field.lat|floatformat:2}} N
>>>> {{field.lon|floatformat:2}} W </td>
>>>> <td class='atable'></td>
>>>> *<td class='atable'>{{packet_data.distance}}</td>*
>>>> <td class='atable'>{{field.dt_heard|date:"D m/d H:i"}}</td>
>>>> </tr>
>>>>
>>>> {% endfor %}
>>>>
>>>>
>>>> --
> You received this message because you are subscribed to the Google Groups
> "Django users" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to django-users+unsubscr...@googlegroups.com.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/django-users/b5115c63-e000-48ee-8e5d-7f923c12731bn%40googlegroups.com
> <https://groups.google.com/d/msgid/django-users/b5115c63-e000-48ee-8e5d-7f923c12731bn%40googlegroups.com?utm_medium=email&utm_source=footer>
> .
>
--
You received this message because you are subscribed to the Google Groups
"Django users" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to django-users+unsubscr...@googlegroups.com.
To view this discussion on the web visit
https://groups.google.com/d/msgid/django-users/CAN0Tv2UUioj4SS-P5a-AFjUqAPwP2_yMxQ4zX06zaprQTf1wfg%40mail.gmail.com.
