Adding a new object in the ephem database

[Paul Bartholdi]

Hi,

I nodified a few years ago the "Standard/index.html.tmpl" to print the main solar systems objects (sun, moon, Jupiter...).

Now I want to pint the same informations but for the minor planet Eros that pass very (very relative!) the earth in the few next days.

This implies adding the python line:

     eros = ephem.readdb("433 Eros,e,10.8276,304.3222,178.8165,1.457940,0.5598795,0.22258902,71.2803,09/04.0/2017,2000,H11.16,0.46")

and then (in index.html.tmp) :

               <tr>

                  <td class="label">Rise  :</td>

                  <td class="data">$almanac.eros.rise</td>

                </tr>

Where should I add the " eros = ephem.readdb(...) line ?   ( index.html.tmpl ?  almanac.py ? elsewhere ?).

Thanks for any help/advice!     Paul

[Thomas Keffer]

This is a good question, and it took me a while to figure out how to work around the limitations of pyephem. Try this:

1. Put the following in user/extensions.py:

import ephem

eros = ephem.readdb("433 Eros,e,10.8276,304.3222,178.8165,1.457940,0.5598795,0.22258902,71.2803,09/04.0/2017,2000,H11.16,0.46")

ephem.Eros = eros

2. Modify the WeeWX module weewx/almanac.py so that the function _get_ephem_body() looks like this:

def _get_ephem_body(heavenly_body):

    # The library 'ephem' refers to heavenly bodies using a capitalized

    # name. For example, the module used for 'mars' is 'ephem.Mars'.

    cap_name = heavenly_body.capitalize()

    

    # If the heavenly body is a star, or if the body does not exist, then an

    # exception will be raised. Be prepared to catch it.

    try:

        ephem_body = getattr(ephem, cap_name)()

    except AttributeError:

        # That didn't work. Try a star. If this doesn't work either,

        # then a KeyError exception will be raised.

        ephem_body = ephem.star(cap_name)

    except TypeError:

        ephem_body = getattr(ephem, cap_name)

    return ephem_body

You are adding the two highlighted lines.

3. Then use this in your template:

$almanac.eros.rise

for when it rises, etc. (treat it just like any other planet).

Double check the answer. I'm not 100% confident this will work. If it does, I'll add the changes for weewx/almanac.py to the code base.

-tk

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[gjr80]

This will be handy provided it works, I have had a few extra stars that I wanted to include in some reports. Some I have picked up by downloading the latest stars.py from the pyephem repo but there are others that are not included in pyephem. This gives me a suitable way to add them.

Gary

[Paul Bartholdi]

Dear Thommas,

Once more you impressed me a lot, such quick and well formed answer. Thanks.

Now I am afraid to say that there is still a buf, probably a typo or some thing like that. I checked "my" additions in "extensions.py" and "almanac.py" (and of course in "index.html.tmpl"), and believe they were correctly done.

Just a question: where can I find the generated file  "cheetah__etc_weewx_skins_Standard_index_html_tmpl_1548001524_26_16364.py" ?

Here is the .log of the error:

reportengine: Found configuration file /etc/weewx/skins/Standard/skin.conf for report StandardReport

cheetahgenerator: using search list ['weewx.cheetahgenerator.Almanac', 'weewx.cheetahgenerator.Station', 'weewx.cheetahgenerator.Current', 'weewx.cheetahgenerator.Stats', 'weewx.cheetahgenerator.UnitInfo', 'weewx.cheetahgenerator.Extras']

manager: Daily summary version is 2.0

cheetahgenerator: Generate failed with exception '<type 'exceptions.TypeError'>'

cheetahgenerator: **** Ignoring template /etc/weewx/skins/Standard/index.html.tmpl

cheetahgenerator: **** Reason: 'ephem.EllipticalBody' object is not callable

****  Traceback (most recent call last):

****    File "/usr/share/weewx/weewx/cheetahgenerator.py", line 330, in generate

****      print >> _file, compiled_template

****    File "/usr/lib/python2.7/dist-packages/Cheetah/Template.py", line 1005, in __str__

****      rc = getattr(self, mainMethName)()

****    File "cheetah__etc_weewx_skins_Standard_index_html_tmpl_1548001524_26_16364.py", line 2545, in respond

****    File "cheetah__etc_weewx_skins_Standard_index_html_tmpl_1548001524_26_16364.py", line 1155, in __errorCatcher156

****    File "<string>", line 1, in <module>

****    File "/usr/share/weewx/weewx/almanac.py", line 355, in __getattr__

****      ephem_body = _get_ephem_body(self.heavenly_body)

****    File "/usr/share/weewx/weewx/almanac.py", line 424, in _get_ephem_body

****      ephem_body = getattr(ephem, cap_name)()

****  TypeError: 'ephem.EllipticalBody' object is not callable

cheetahgenerator: Generated 13 files for report StandardReport in 0.56 seconds

manager: Daily summary version is 2.0

Best regards,     Paul

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[Thomas Keffer]

This is the error I got before modifying almanac.py. Make sure you're using the version of almanac.py you think you are.

I've attached the patched version I'm using.

-tk

[Paul Bartholdi]

Dear Thomas, 

Just a line to say that now everything is perfect (see http://shire-bdi.gotdns.com/weewx ). ! Thank for all your help.    Paul