Re: Filling in Degrees in a Circle (Astronomy)
On Aug 23, 6:12 am, "W. eWatson" <[EMAIL PROTECTED]> 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. > > -- > 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: Linear interpolation is simple, any mathematician would know. It's just like this: hA = height at point A hB = height at point B hN = height at point N (what we're finding) l = horizontal distance between A and B n = horizontal position measured from A hN = hA + ((n / l) * (hB - hA)) so: def interpolate(n, A, B): # A, B is two-tuple of (angle, height) of # the nearest known points surrounding n oA, hA = A oB, hB = B l = oB - oA return hA + ((n / l) * (hB - hA)) -- http://mail.python.org/mailman/listinfo/python-list
Re: Filling in Degrees in a Circle (Astronomy)
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.
Using one of the Python maths packages (scipy, sage, ...) is no doubt
better, but out of interest here is some first-principles interpolation:
8<-
class NewtonInterpolatingPolynomial(object):
def __init__(self):
self._domain = []
self._codomain = []
self._diffs = None
self._coeffs = []
def add_data_point(self, x, y):
self._domain.append(x)
self._codomain.append(y)
if self._diffs is None:
self._diffs = {}
else:
degree = len(self._domain) - 2
_x = self._domain[-2]
_y = self._codomain[-2]
self._diffs[(degree, degree+1)] = (y - _y) / (x - _x)
indices = range(degree+2)
for t in ( tuple(indices[i:]) for i in
reversed(indices[:-2]) ):
denominator = self._domain[t[0]] - self._domain[t[-1]]
k, _k = self._diffs[t[1:]], self._diffs[t[:-1]]
self._diffs[t] = (_k - k) / denominator
self._coeffs.append(self._diffs[tuple(indices)])
def __str__(self):
N = len(self._domain)
if not N:
return ''
parts = [str(self._codomain[0])]
multipliers = [''.join(('(X - ',str(C),')')) for C in
self._domain[:-1]]
for i, k in enumerate(self._coeffs):
parts.append('*'.join([str(k)] + multipliers[:i+1]))
return ' + '.join(parts)
def interpolate(self, gamma):
#return eval(str(self).replace('X', str(gamma)))
ret = self._codomain[0]
K = 1
multipliers = [gamma-C for C in self._domain[:-1]]
for i, k in enumerate(multipliers):
K *= k
ret += self._coeffs[i] * K
return ret
def __call__(self, x):
return self.interpolate(x)
rawdata = '''
018
18 18
27 16
34 20
48 20
59 28
72 32
'''
data = [map(float, line.split() ) for line in rawdata.splitlines() if line]
newton = NewtonInterpolatingPolynomial()
for x, y in data:
newton.add_data_point(x, y)
print newton
for P in range(80):
print P, '-> ', newton(P)
18.0 + 0.0*(X - 0.0) + -0.0082304526749*(X - 0.0)*(X - 18.0) +
0.00170098903759*(X - 0.0)*(X - 18.0)*(X - 27.0) + -8.87803681143e-05*(X
- 0.0)*(X - 18.0)*(X - 27.0)*(X - 34.0) + 3.29057245545e-06*(X - 0.0)*(X
- 18.0)*(X - 27.0)*(X - 34.0)*(X - 48.0) + -8.98633510787e-08*(X -
0.0)*(X - 18.0)*(X - 27.0)*(X - 34.0)*(X - 48.0)*(X - 59.0)
0 -> 18.0
1 -> 26.0156268043
2 -> 31.8038369501
3 -> 35.719116702
4 -> 38.0797664434
5 -> 39.1701395406
6 -> 39.2428165062
7 -> 38.5207144606
8 -> 37.1991318912
9 -> 35.4477287116
10 -> 33.4124416172
11 -> 31.2173347409
12 -> 28.9663856061
13 -> 26.7452063785
14 -> 24.6227004166
15 -> 22.6526541194
16 -> 20.8752640745
17 -> 19.3185995022
18 -> 18.0
19 -> 16.9274085845
20 -> 16.1006400316
21 -> 15.5125845157
22 -> 15.1503465468
23 -> 14.996319206
24 -> 15.0291936797
25 -> 15.2249040921
26 -> 15.5575076355
27 -> 16.0
28 -> 16.525066101
29 -> 17.1057661048
30 -> 17.7161567532
31 -> 18.3318479864
32 -> 18.9304948638
33 -> 19.4922247833
34 -> 20.0
35 -> 20.4399154416
36 -> 20.8014318237
37 -> 21.0775440624
38 -> 21.2648849859
39 -> 21.3637643445
40 -> 21.3781431185
41 -> 21.3155431251
42 -> 21.1868919232
43 -> 21.0063030167
44 -> 20.7907913565
45
Re: Filling in Degrees in a Circle (Astronomy)
On Aug 23, 10:11 am, Scott David Daniels <[EMAIL PROTECTED]>
wrote:
> W. eWatson wrote:
> > ...
> > I'm working on this now, but my knowledge of python needs refreshing.
> > Right now I have a file of all the az,el data I've collected, and I'd
> > like to open it with Python for XP. However, Python doesn't like this:
>
> > junkfile = open('c:\tmp\junkpythonfile','w')
>
> > I get
> > junkfile = open('c:\tmp\junkpythonfile','w')
> > IOError: [Errno 2] No such file or directory: 'c:\tmp\\junkpythonfile'
>
> > This problematic segment is just a hack of a similar statement which has
> > the same problem and a much longer path. I suspect the problem is with
> > the back slash.
>
> A standard windows error. note that '\t' is a tab, and I doubt you have
> a directory named . Get in the habit of _always_ using:
> junkfile = open(r'c:\tmp\junkpythonfile','w')
> or
> junkfile = open('c:\\tmp\\junkpythonfile','w')
> for file names.
>
> --Scott David Daniels
> [EMAIL PROTECTED]
Avoid backslashes whenever possible.
junkfile = open('c:/tmp/junkpythonfile','w')
--
http://mail.python.org/mailman/listinfo/python-list
Re: Filling in Degrees in a Circle (Astronomy)
http://matplotlib.sourceforge.net/ I'm using Python 2.4. The install looks pretty complicated for Windows. It doesn't seem like matplotlib is a module. Maybe going with the enthought edition would be easiest for you as it is a very complete set of tools all in one package. It's at http://www.enthought.com/products/epd.php These are really nice tools for scientific (and other) data analysis, and are very competitive with most professional packages. There are other bundles as well, like Sage. I've always used enthought. On the other hand, I think making tools that use these in a bundled exe might be more difficult, and if possible, might not be consistent with their license agreements, and might make for large packages. I never really looked into this. Also, with matplotlib, you might just try installing it without anything else and see how it goes. Just download the exe and double-click, or the egg file and do whatever one does with those. I bet it will work... I think it will just default to using Tk for the GUI, which you already have installed with Python, and it won't use agg (an anti-aliasing library), so your plots won't be quite as pretty. But they'll still be nice, and it will likely work. -- http://mail.python.org/mailman/listinfo/python-list
Re: Filling in Degrees in a Circle (Astronomy)
David wrote: What modules do I need to use pylab? I've installed scipy and numpy. http://matplotlib.sourceforge.net/ I'm using Python 2.4. The install looks pretty complicated for Windows. It doesn't seem like matplotlib is a module. -- 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: -- http://mail.python.org/mailman/listinfo/python-list
Re: Filling in Degrees in a Circle (Astronomy)
What modules do I need to use pylab? I've installed scipy and numpy. http://matplotlib.sourceforge.net/ -- Have Fun, David A. Powered by Gentoo GNU/LINUX http://www.linuxcrazy.com -- http://mail.python.org/mailman/listinfo/python-list
Re: Filling in Degrees in a Circle (Astronomy)
W. eWatson schreef: I completed a Win Python program and it has generated the necessary data, which I have in turn used successfully with the telescope software. Is there some way to turn this into an executable program for people who do not have Python? Yes, you can use py2exe (http://www.py2exe.org/) for that. -- The saddest aspect of life right now is that science gathers knowledge faster than society gathers wisdom. -- Isaac Asimov Roel Schroeven -- http://mail.python.org/mailman/listinfo/python-list
Re: Filling in Degrees in a Circle (Astronomy)
tom wrote: W. eWatson wrote: 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? Both scipy and matplotlib are not part of the standard Python distribution so they would need to be installed separately. Scipy is useful for scientific data analysis, and matplotlib is useful for making plots. Since you want to wrap everything into a Windows executable, it's probably easiest for you not to use scipy. At the least, I suspect it would make your executable file much larger, but I've never made a Windows executable so I don't know the details. As for making an executable, I'm not the one to ask, but googling leads to this: http://effbot.org/pyfaq/how-can-i-create-a-stand-alone-binary-from-a-python-script.htm which looks like a good place to start. Tom What modules do I need to use pylab? I've installed scipy and numpy. -- 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: -- http://mail.python.org/mailman/listinfo/python-list
Re: Filling in Degrees in a Circle (Astronomy)
tom wrote: Both scipy and matplotlib are not part of the standard Python distribution so they would need to be installed separately. Scipy is useful for scientific data analysis, and matplotlib is useful for making plots. For a review of a really nice looking wrapper around lots of open-source mathematical tools, look here: http://vnoel.wordpress.com/2008/05/03/bye-matlab-hello-python-thanks-sage/ it is called SAGE and includes both of the above and lots more goodies. for sage itself: http://www.sagemath.org/ -- http://mail.python.org/mailman/listinfo/python-list
Re: Filling in Degrees in a Circle (Astronomy)
W. eWatson wrote: 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? Both scipy and matplotlib are not part of the standard Python distribution so they would need to be installed separately. Scipy is useful for scientific data analysis, and matplotlib is useful for making plots. Since you want to wrap everything into a Windows executable, it's probably easiest for you not to use scipy. At the least, I suspect it would make your executable file much larger, but I've never made a Windows executable so I don't know the details. As for making an executable, I'm not the one to ask, but googling leads to this: http://effbot.org/pyfaq/how-can-i-create-a-stand-alone-binary-from-a-python-script.htm which looks like a good place to start. Tom -- http://mail.python.org/mailman/listinfo/python-list
Re: Filling in Degrees in a Circle (Astronomy)
Dennis Lee Bieber wrote:
On Fri, 22 Aug 2008 23:18:17 -0700, "W. eWatson"
<[EMAIL PROTECTED]> declaimed the following in comp.lang.python:
I'll take a look. I just posted above yours with a more insightful set of
data than the first three pointer. Yes, some way of bisecting, or chopping
is the trick here. One is just trying to fill in all the gaps with
interpolation and produce 360 points to feed to the telescope software. It's
sort of like giving someone, and forgetting interpolation here, the sequence
20, 30, blank, 60, 70, 80 and asking for the two missing tens between 30 and
60. 40 and 50, of course.
Presuming the data is an ordered list (in azimuth) of az/el pairs,
AND that the last measurement does not close the circle (eg: (0, 1),
(90, 5), (180, 5), (270, 2) ) the first step would be to append a data
point consisting of the first azimuth data point + 360, but with the
same elevation value. With normalization at the output, this would work
if the first data point was not at 0. Then one would perform repeated
interpolations over pairs of data points, outputting the first pair as
the first value, and stopping when the azimuth reached the second pair.
Something like (watch out for line wrapping):
-=-=-=-=-=-=-
import pprint
def gatherPoints():
pointList = []
while True:
cAz = raw_input("Enter Azimuth in integer degrees (blank line to
exit) : ")
cAz = cAz.strip()
if not cAz: break
az = int(cAz)
cEl = raw_input("Enter Elevation in real degrees for azimuth %s
: " % az).strip()
el = float(cEl)
pointList.append( (az, el) )
if pointList:
pointList.append( (pointList[0][0] + 360, pointList[0][1]) )
return pointList
def interpolate(start, end, step):
slope = float(end[1] - start[1]) / (end[0] - start[0])
iPoints = [ (i, (slope * (i - start[0])) + start[1])
for i in range(start[0], end[0], step) ]
return iPoints
if __name__ == "__main__":
points = gatherPoints()
output = []
if points:
for s in range(len(points) - 1):
output.extend(interpolate(points[s], points[s+1], 1))
pprint.pprint(output)
-=-=-=-=-=-=-
Close. A nice looking piece of code. Something for me to learn from. I play
with python on a pretty irregular basis.
The game here is like someone gives you five distinct integer numbers from 1
to 10 in order, and one needs to write a program to fill in the gaps. In my
case, the numbers go from 0 to 359, and I have lots of gaps. I gave a pretty
illustrative example in a post above. 11:10 pm last night. Of course, not
only the gaps from 0 to 359 need to be filled in, but the interpolated
values of the related values need to be obtained. Elevation.
As I just posted to the fellow below you. 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.
--
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:
--
http://mail.python.org/mailman/listinfo/python-list
Re: Filling in Degrees in a Circle (Astronomy)
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: -- http://mail.python.org/mailman/listinfo/python-list
Re: Filling in Degrees in a Circle (Astronomy)
I completed a Win Python program and it has generated the necessary data, which I have in turn used successfully with the telescope software. Is there some way to turn this into an executable program for people who do not have Python? -- 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: -- http://mail.python.org/mailman/listinfo/python-list
Re: Filling in Degrees in a Circle (Astronomy)
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() -- http://mail.python.org/mailman/listinfo/python-list
Re: Filling in Degrees in a Circle (Astronomy)
Scott David Daniels wrote:
W. eWatson wrote:
...
I'm working on this now, but my knowledge of python needs refreshing.
Right now I have a file of all the az,el data I've collected, and I'd
like to open it with Python for XP. However, Python doesn't like this:
junkfile = open('c:\tmp\junkpythonfile','w')
I get
junkfile = open('c:\tmp\junkpythonfile','w')
IOError: [Errno 2] No such file or directory: 'c:\tmp\\junkpythonfile'
This problematic segment is just a hack of a similar statement which
has the same problem and a much longer path. I suspect the problem is
with the back slash.
A standard windows error. note that '\t' is a tab, and I doubt you have
a directory named . Get in the habit of _always_ using:
junkfile = open(r'c:\tmp\junkpythonfile','w')
or
junkfile = open('c:\\tmp\\junkpythonfile','w')
for file names.
--Scott David Daniels
[EMAIL PROTECTED]
Thanks. r did the job nicely.
--
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:
--
http://mail.python.org/mailman/listinfo/python-list
Re: Filling in Degrees in a Circle (Astronomy)
W. eWatson wrote:
...
I'm working on this now, but my knowledge of python needs refreshing.
Right now I have a file of all the az,el data I've collected, and I'd
like to open it with Python for XP. However, Python doesn't like this:
junkfile = open('c:\tmp\junkpythonfile','w')
I get
junkfile = open('c:\tmp\junkpythonfile','w')
IOError: [Errno 2] No such file or directory: 'c:\tmp\\junkpythonfile'
This problematic segment is just a hack of a similar statement which has
the same problem and a much longer path. I suspect the problem is with
the back slash.
A standard windows error. note that '\t' is a tab, and I doubt you have
a directory named . Get in the habit of _always_ using:
junkfile = open(r'c:\tmp\junkpythonfile','w')
or
junkfile = open('c:\\tmp\\junkpythonfile','w')
for file names.
--Scott David Daniels
[EMAIL PROTECTED]
--
http://mail.python.org/mailman/listinfo/python-list
Re: Filling in Degrees in a Circle (Astronomy)
Carl Banks wrote: On Aug 22, 7:12 pm, "W. eWatson" <[EMAIL PROTECTED]> wrote: 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? There's nothing built in, but see the bisect module. It is a good way to determine which interval you are in, and you can interpolate the points yourself. Carl Banks I'll take a look. I just posted above yours with a more insightful set of data than the first three pointer. Yes, some way of bisecting, or chopping is the trick here. One is just trying to fill in all the gaps with interpolation and produce 360 points to feed to the telescope software. It's sort of like giving someone, and forgetting interpolation here, the sequence 20, 30, blank, 60, 70, 80 and asking for the two missing tens between 30 and 60. 40 and 50, of course. The fellow above wrote an interpolate function that will probably fit the bill. -- 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: -- http://mail.python.org/mailman/listinfo/python-list
Re: Filling in Degrees in a Circle (Astronomy)
Maric Michaud wrote:
Le Saturday 23 August 2008 01:12:48 W. eWatson, vous avez écrit :
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.
Not sure I got it, but is that fulfill your specs ?
[20]: def interpolate(a, b) :
slope = float(b[1] - a[1]) / (b[0] - a[0])
return [ slope * float(i) for i in xrange(b[0]-a[0] + 1) ]
:
[23]: interpolate((0, 0), (180, 45))
...[23]:
[0.0,
0.25,
0.5,
0.75,
44.5,
44.75,
45.0]
[29]: interpolate((80, 20), (180, 45))
[0.0,
0.25,
0.5,
0.75,
1.0,
1.25,
...
24.5,
24.75,
25.0]
Yes, the interpolation part looks right, but the tricky part is to be able
to go through the list and find where one needs to generate all the missing
az angles. A chunk of my data is in a post above yours. Here's a more
revealing set of data where four data points are known:
az el
0 10
4 14 (slope is 1)
12 30 (slope is 2)
15 15 (slope is -5)
16 points need to be generated, 0 to 15, representing 15 degrees around the
circle.
So, I'm doing this in my head, one would get
0 10 (slope is 1)
1 11
2 12
3 13
4 14
5 16 (slope is 2)
6 18
7 18
...
12 30
13 25
14 20
15 15
I use Python occasionally, and starting up requires some effort, but I've
finally decided to take a go at this.
I'm working on this now, but my knowledge of python needs refreshing. Right
now I have a file of all the az,el data I've collected, and I'd like to open
it with Python for XP. However, Python doesn't like this:
junkfile = open('c:\tmp\junkpythonfile','w')
I get
junkfile = open('c:\tmp\junkpythonfile','w')
IOError: [Errno 2] No such file or directory: 'c:\tmp\\junkpythonfile'
This problematic segment is just a hack of a similar statement which has the
same problem and a much longer path. I suspect the problem is with the back
slash.
--
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:
--
http://mail.python.org/mailman/listinfo/python-list
Re: Filling in Degrees in a Circle (Astronomy)
On Aug 22, 7:12 pm, "W. eWatson" <[EMAIL PROTECTED]> wrote: > 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? There's nothing built in, but see the bisect module. It is a good way to determine which interval you are in, and you can interpolate the points yourself. Carl Banks -- http://mail.python.org/mailman/listinfo/python-list
Re: Filling in Degrees in a Circle (Astronomy)
Le Saturday 23 August 2008 01:12:48 W. eWatson, vous avez écrit : > 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. Not sure I got it, but is that fulfill your specs ? >>>[20]: def interpolate(a, b) : slope = float(b[1] - a[1]) / (b[0] - a[0]) return [ slope * float(i) for i in xrange(b[0]-a[0] + 1) ] : >>>[23]: interpolate((0, 0), (180, 45)) ...[23]: [0.0, 0.25, 0.5, 0.75, 44.5, 44.75, 45.0] >>>[29]: interpolate((80, 20), (180, 45)) [0.0, 0.25, 0.5, 0.75, 1.0, 1.25, ... 24.5, 24.75, 25.0] -- _ Maric Michaud -- http://mail.python.org/mailman/listinfo/python-list
Re: Filling in Degrees in a Circle (Astronomy)
Mensanator wrote: On Aug 22, 6:12 pm, "W. eWatson" <[EMAIL PROTECTED]> 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. On Aug 22, 6:12 pm, "W. eWatson" <[EMAIL PROTECTED]> 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. for az in xrange(181): print (az,az*0.25), (0, 0.0) (1, 0.25) (2, 0.5) (3, 0.75) (4, 1.0) (5, 1.25) (6, 1.5) (7, 1.75) (8, 2.0) (9, 2.25) (10, 2.5) (11, 2.75) (12, 3.0) (13, 3.25) (14, 3.5) (15, 3.75) (16, 4.0) (17, 4.25) (18, 4.5) (19, 4.75) (20, 5.0) (21, 5.25) (22, 5.5) (23, 5.75) etc. Yes, that works, but that was only a simple illustration. My data looks in fact looks like this (only a few values given: Az Alt 018 18 18 27 16 34 20 48 20 ... 268 28 290 32 ... So the python software should generate 0 18 1 18 2 18 3 18 ... the trees are all about 18 degrees high 18 18 19 17.9 we have a slight slope. I'm using values that might be close 20 27.75 21 ... 27 16 28 16.4 now the trees are starting to get a little higher 29 16.9 ... 359 18 (most likely. I didn't have the patience to make a measure at 359) That should pretty well illustrate it. In actuality, as I swept around the circle, the tree line becomes much more abrupt than those first few data points. The tallest tree is at 36 degrees and is among some other equally tall trees. But are you saying if you have two readings of tree tops * * x * x * * x * * x * *_x_*__ And you linearly interpret between them exactly. I put a value there -- x / /* / * / * / * /* * * * *___*__ that the area below the dashed line is assumed to be hidden? Yes, the telescope software will see that it cannot move the telescope into that area. Surprisingly, they use interpolation. For example, suppose the two trees in your illustration are at an az of 100 and 101, and the two altitudes are 3 and 7. Suppose the telescope wants to go below the line into 100.622 az and an alt of 2.42. The software will say no you don't. That wouldn't necessarily be true, as the tree profile could dip below the line. / /* / * / ** / *** /* ** ___***_ Of course, if you take enough points, the open areas may be small enough not to be practical to worry about. -- http://mail.python.org/mailman/listinfo/python-list
Re: Filling in Degrees in a Circle (Astronomy)
On Aug 22, 6:12 pm, "W. eWatson" <[EMAIL PROTECTED]> 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. On Aug 22, 6:12 pm, "W. eWatson" <[EMAIL PROTECTED]> 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. >>> for az in xrange(181): print (az,az*0.25), (0, 0.0) (1, 0.25) (2, 0.5) (3, 0.75) (4, 1.0) (5, 1.25) (6, 1.5) (7, 1.75) (8, 2.0) (9, 2.25) (10, 2.5) (11, 2.75) (12, 3.0) (13, 3.25) (14, 3.5) (15, 3.75) (16, 4.0) (17, 4.25) (18, 4.5) (19, 4.75) (20, 5.0) (21, 5.25) (22, 5.5) (23, 5.75) etc. But are you saying if you have two readings of tree tops * * * * * * * * *___*__ And you linearly interpret between them / /* / * / * / * /* * * * *___*__ that the area below the dashed line is assumed to be hidden? That wouldn't necessarily be true, as the tree profile could dip below the line. / /* / * / ** / *** /* ** ___***_ Of course, if you take enough points, the open areas may be small enough not to be practical to worry about. > -- > 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: > -- > 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: -- http://mail.python.org/mailman/listinfo/python-list
