Filling in Degrees in a Circle (Astronomy)

[W. eWatson]

tom wrote:
> W. eWatson wrote:
>> The other night I surveyed a site for astronomical use by measuring 
>> the altitude (0-90 degrees above the horizon) and az (azimuth, 0 
>> degrees north clockwise around the site to 360 degrees, almost north 
>> again) of obstacles, trees. My purpose was to feed this profile of 
>> obstacles (trees) to an astronomy program that would then account for 
>> not sighting objects below the trees.
>>
>> When I got around to entering them into the program by a file, I found 
>> it required the alt at 360 azimuth points in order from 0 to 360 (same 
>> as 0). Instead I have about 25 points, and expected the program to be 
>> able to do simple linear interpolation between those.
>>
>> Is there some simple operational device in Python that would allow me 
>> to create an array (vector) of 360 points from my data by 
>> interpolating between azimuth points when necessary? All my data I 
>> rounded to the nearest integer. Maybe there's an interpolation operator?
>>
>> As an example, supposed I had made 3 observations: (0,0) (180,45) and 
>> (360,0). I would want some thing like (note the slope of the line from 
>> 0 to 179 is 45/180 or 0.25):
>> alt: 0, 0.25, 0.50, 0.75, ... 44.75, 45.0
>> az : 0, 1,    2,    3,              180
>>
>> Of course, I don't need the az.
>>
> 
> 
> If I understand you right, I think using interpolation as provided by 
> scipy would do what you need.
> 
> Here's an example:
> 
> from scipy.interpolate.interpolate import interp1d
> 
> angles = [0, 22, 47.5, 180, 247.01, 360]
> altitudes = [18, 18, 26, 3, 5, 18]
> 
> desired_angles = range(0, 361)
> 
> skyline = interp1d(angles, altitudes, kind="linear")
> vals = skyline(desired_angles)
> 
> # that is, vals will be the interpolated altitudes at each of the
> # desired angles.
> 
> if 1:  # plot this out with matplotlib
>     import pylab as mx
>     mx.figure()
>     mx.plot(angles, altitudes, 'x')
>     mx.plot(desired_angles, vals)
>     mx.show()
I decided this morning and roll up my sleeves and write the program. I plan 
to take a deeper plunge in the next month than my so far erratic look over 
the last 18 or more months  It's working.

The above looks like it's on the right track. Is scipy some collection of 
astro programs? mx is a graphics character plot?

I just hauled it into IDLE and tried executing it.
     from scipy.interpolate.interpolate import interp1d
ImportError: No module named scipy.interpolate.interpolate

Apparently, something is missing.

I posted a recent msg a bit higher that will probably go unnoticed, so I'll 
repeat most of it. How do I get my py code into some executable form so that 
Win users who don't have python can execute it?


-- 
            Wayne Watson (Watson Adventures, Prop., Nevada City, CA)

              (121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
               Obz Site:  39° 15' 7" N, 121° 2' 32" W, 2700 feet

                     Web Page: <www.speckledwithstars.net/>