Python3 : unpack requires a bytes object of length 117 - anaconda

Question

I am trying to run script for astronomical algorithm VSOP2013.
but when I running this script, it displays error in line 178
how to solve it?
What's wrong with unpack function?
FYI, the original script is python2, i am using python3
a = self.fmt.unpack(terms.encode())
error: unpack requires a bytes object of length 117
This is my full python3 script, adapted from the original python2 version from http://domenicomustara.blogspot.co.id
# -*- coding: utf-8 -*-
import gmpy2 as gmp
import struct
import ctypes
gmp.get_context().precision=200
def cal2jul(year, month, day, hour=0, minute =0, second=0):
month2 = month
year2 = year
if month2 <= 2:
year2 -= 1
month2 += 12
if (year*10000 + month*100 + day) > 15821015:
a = int(year2/100)
b = 2 - a + int(a/4)
else:
a = 0
b = 0
if year < 0:
c = int((365.25 * year2)-0.75)
else:
c = int(365.25 * year2)
d = int(30.6001 *(month2 + 1))
return b + c + d + day + hour / 24.0 + minute / 1440.0 + second / 86400.0 + 1720994.5
class VSOP2013():
def __init__(self, t, planet, precision=1e-7):
# calculate millennia from J2000
self.JD = t
self.t = gmp.div((t - cal2jul(2000,1,1,12)), 365250.0)
# predefine powers of self.t
self.power = []; self.power.append(gmp.mpfr(1.0)); self.power.append(self.t)
for i in range(2,21):
t = self.power[-1]
self.power.append(gmp.mul(self.t,t))
# choose planet file in a dict
self.planet = planet
self.planets = {'Mercury':'VSOP2013p1.dat',
'Venus' :'VSOP2013p2.dat',
'EMB' :'VSOP2013p3.dat',
'Mars' :'VSOP2013p4.dat',
'Jupiter':'VSOP2013p5.dat',
'Saturn' :'VSOP2013p6.dat',
'Uranus' :'VSOP2013p7.dat',
'Neptune':'VSOP2013p8.dat',
'Pluto' :'VSOP2013p9.dat'}
# VSOP2013 routines precision
self.precision = precision
# lambda coefficients
# l(1,13) : linear part of the mean longitudes of the planets (radian).
# l(14): argument derived from TOP2013 and used for Pluto (radian).
# l(15,17) : linear part of Delaunay lunar arguments D, F, l (radian).
self.l = (
(gmp.mpfr(4.402608631669), gmp.mpfr(26087.90314068555)),
(gmp.mpfr(3.176134461576), gmp.mpfr(10213.28554743445)),
(gmp.mpfr(1.753470369433), gmp.mpfr(6283.075850353215)),
(gmp.mpfr(6.203500014141), gmp.mpfr(3340.612434145457)),
(gmp.mpfr(4.091360003050), gmp.mpfr(1731.170452721855)),
(gmp.mpfr(1.713740719173), gmp.mpfr(1704.450855027201)),
(gmp.mpfr(5.598641292287), gmp.mpfr(1428.948917844273)),
(gmp.mpfr(2.805136360408), gmp.mpfr(1364.756513629990)),
(gmp.mpfr(2.326989734620), gmp.mpfr(1361.923207632842)),
(gmp.mpfr(0.599546107035), gmp.mpfr(529.6909615623250)),
(gmp.mpfr(0.874018510107), gmp.mpfr(213.2990861084880)),
(gmp.mpfr(5.481225395663), gmp.mpfr(74.78165903077800)),
(gmp.mpfr(5.311897933164), gmp.mpfr(38.13297222612500)),
(gmp.mpfr(0.000000000000), gmp.mpfr(0.3595362285049309)),
(gmp.mpfr(5.198466400630), gmp.mpfr(77713.7714481804)),
(gmp.mpfr(1.627905136020), gmp.mpfr(84334.6615717837)),
(gmp.mpfr(2.355555638750), gmp.mpfr(83286.9142477147)))
# planetary frequencies in longitude
self.freqpla = {'Mercury' : gmp.mpfr(0.2608790314068555e5),
'Venus' : gmp.mpfr(0.1021328554743445e5),
'EMB' : gmp.mpfr(0.6283075850353215e4),
'Mars' : gmp.mpfr(0.3340612434145457e4),
'Jupiter' : gmp.mpfr(0.5296909615623250e3),
'Saturn' : gmp.mpfr(0.2132990861084880e3),
'Uranus' : gmp.mpfr(0.7478165903077800e2),
'Neptune' : gmp.mpfr(0.3813297222612500e2),
'Pluto' : gmp.mpfr(0.2533566020437000e2)}
# target variables
self.ax = gmp.mpfr(0.0) # major semiaxis
self.ml = gmp.mpfr(0.0) # mean longitude
self.kp = gmp.mpfr(0.0) # e*cos(perielium longitude)
self.hp = gmp.mpfr(0.0) # e*sin(perielium longitude)
self.qa = gmp.mpfr(0.0) # sin(inclination/2)*cos(ascending node longitude)
self.pa = gmp.mpfr(0.0) # sin(inclination/2)*cos(ascending node longitude)
self.tg_var = {'A':self.ax, 'L':self.ml, 'K':self.kp,
'H':self.hp, 'Q':self.qa, 'P':self.pa }
# eps = (23.d0+26.d0/60.d0+21.41136d0/3600.d0)*dgrad
self.eps = gmp.mpfr((23.0+26.0/60.0+21.411360/3600.0)*gmp.const_pi()/180.0)
self.phi = gmp.mpfr(-0.051880 * gmp.const_pi() / 180.0 / 3600.0)
self.ceps = gmp.cos(self.eps)
self.seps = gmp.sin(self.eps)
self.cphi = gmp.cos(self.phi)
self.sphi = gmp.sin(self.phi)
# rotation of ecliptic -> equatorial rect coords
self.rot = [[self.cphi, -self.sphi*self.ceps, self.sphi*self.seps],
[self.sphi, self.cphi*self.ceps, -self.cphi*self.seps],
[0.0, self.seps, self.ceps ]]
self.fmt = struct.Struct("""6s 3s 3s 3s 3s x 3s 3s 3s 3s 3s x 4s 4s 4s 4s x
6s x 3s 3s 3s 20s x 3s 20s x 3s x""")
self.gmp_ = {
'Mercury' : gmp.mpfr(4.9125474514508118699e-11),
'Venus' : gmp.mpfr(7.2434524861627027000e-10),
'EMB' : gmp.mpfr(8.9970116036316091182e-10),
'Mars' : gmp.mpfr(9.5495351057792580598e-11),
'Jupiter' : gmp.mpfr(2.8253458420837780000e-07),
'Saturn' : gmp.mpfr(8.4597151856806587398e-08),
'Uranus' : gmp.mpfr(1.2920249167819693900e-08),
'Neptune' : gmp.mpfr(1.5243589007842762800e-08),
'Pluto' : gmp.mpfr(2.1886997654259696800e-12)}
self.gmsol = gmp.mpfr(2.9591220836841438269e-04)
self.rgm = gmp.sqrt(self.gmp_[self.planet]+self.gmsol)
# run calculus routine
self.calc()
def __str__(self):
vsop_out = "{:3.13} {:3.13} {:3.13} {:3.13} {:3.13} {:3.13}\n".format(
self.tg_var['A'],
self.tg_var['L'],
self.tg_var['K'],
self.tg_var['H'],
self.tg_var['Q'],
self.tg_var['P'])
vsop_out += "{:3.13} {:3.13} {:3.13} {:3.13} {:3.13} {:3.13}\n".format(
self.ecl[0],
self.ecl[1],
self.ecl[2],
self.ecl[3],
self.ecl[4],
self.ecl[5])
vsop_out += "{:3.13} {:3.13} {:3.13} {:3.13} {:3.13} {:3.13}\n".format(
self.equat[0],
self.equat[1],
self.equat[2],
self.equat[3],
self.equat[4],
self.equat[5])
return vsop_out
def calc(self):
with open(self.planets[self.planet]) as file_in:
terms = []
b = '*'
while b != '':
b = file_in.readline()
if b != '':
if b[:5] == ' VSOP':
header = b.split()
#print header[3], header[7], header[8], self.t**int(header[3])
no_terms = int(header[4])
for i in range(no_terms):
#6x,4i3,1x,5i3,1x,4i4,1x,i6,1x,3i3,2a24
terms = file_in.readline()
# print('terms',terms)
a = self.fmt.unpack(terms.encode())
S = gmp.mul(gmp.mpfr(a[18]),gmp.exp10(int(a[19])))
C = gmp.mul(gmp.mpfr(a[20]),gmp.exp10(int(a[21])))
if gmp.sqrt(S*S+C*C) < self.precision:
break
aa = 0.0; bb = 0.0;
for j in range(1,18):
aa += gmp.mul(gmp.mpfr(a[j]), self.l[j-1][0])
bb += gmp.mul(gmp.mpfr(a[j]), self.l[j-1][1])
arg = aa + bb * self.t
power = int(header[3])
comp = self.power[power] * (S * gmp.sin(arg) + C * gmp.cos(arg))
if header[7] == 'L' and power == 1 and int(a[0]) == 1:
pass
else:
self.tg_var[header[7]] += comp
self.tg_var['L'] = self.tg_var['L'] + self.t * self.freqpla[self.planet]
self.tg_var['L'] = self.tg_var['L'] % (2 * gmp.const_pi())
if self.tg_var['L'] < 0:
self.tg_var['L'] += 2*gmp.const_pi()
print ("Julian date {}".format(self.JD))
file_in.close()
##print self.tg_var
#### def ELLXYZ(self):
xa = self.tg_var['A']
xl = self.tg_var['L']
xk = self.tg_var['K']
xh = self.tg_var['H']
xq = self.tg_var['Q']
xp = self.tg_var['P']
# Computation
xfi = gmp.sqrt(1.0 -xk * xk - xh * xh)
xki = gmp.sqrt(1.0 -xq * xq - xp * xp)
u = 1.0/(1.0 + xfi)
z = complex(xk, xh)
ex = abs(z)
ex2 = ex * ex
ex3 = ex2 * ex
z1 = z.conjugate()
#
gl = xl % (2*gmp.const_pi())
gm = gl - gmp.atan2(xh, xk)
e = gl + (ex - 0.1250 * ex3) * gmp.sin(gm)
e += 0.50 * ex2 * gmp.sin(2.0 * gm)
e += 0.3750 * ex3 * gmp.sin(3.0 * gm)
#
while True:
z2 = complex(0.0, e)
zteta = gmp.exp(z2)
z3 = z1 * zteta
dl = gl - e + z3.imag
rsa = 1.0 - z3.real
e = e + dl / rsa
if abs(dl) < 1e-15:
break
#
z1 = u * z * z3.imag
z2 = gmp.mpc(z1.imag, -z1.real)
zto = (-z+zteta+z2)/rsa
xcw = zto.real
xsw = zto.imag
xm = xp * xcw - xq * xsw
xr = xa * rsa
#
self.ecl = []; self.equ = {}
self.ecl.append(xr * (xcw -2.0 *xp * xm))
self.ecl.append(xr * (xsw +2.0 *xq * xm))
self.ecl.append(-2.0 * xr * xki * xm)
#
xms = xa *(xh + xsw) / xfi
xmc = xa *(xk + xcw) / xfi
xn = self.rgm / xa ** (1.50)
#
self.ecl.append( xn *((2.0 * xp * xp - 1.0) * xms + 2.0 * xp * xq * xmc))
self.ecl.append( xn *((1.0 -2.0 * xq * xq) * xmc -2.0 * xp * xq * xms))
self.ecl.append( 2.0 * xn * xki * (xp * xms + xq * xmc))
# Equatorial rectangular coordinates and velocity
#
#
# --- Computation ------------------------------------------------------
#
self.equat = [0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
for i in range(3):
for j in range(3):
self.equat[i] = self.equat[i] + self.rot[i][j] * self.ecl[j]
self.equat[i+3] = self.equat[i+3] + self.rot[i][j] * self.ecl[j+3]
if __name__ == '__main__':
for planet in ('Mercury', 'Venus', 'EMB', 'Mars', 'Jupiter',
'Saturn', 'Uranus', 'Neptune', 'Pluto'):
print ("PLANETARY EPHEMERIS VSOP2013 "+ planet + "(TDB)\n"+"""
1/ Elliptic Elements: a (au), lambda (radian), k, h, q, p - Dynamical Frame J2000
2/ Ecliptic Heliocentric Coordinates: X,Y,Z (au) X',Y',Z' (au/d) - Dynamical Frame J2000
3/ Equatorial Heliocentric Coordinates: X,Y,Z (au) X',Y',Z' (au/d) - ICRS Frame J2000
""")
init_date = cal2jul(1890,6,26,12)
set_date = init_date
while set_date < init_date + 41000:
v = VSOP2013(set_date, planet)
print (v)
set_date += 4000
Respond comment from Mr.barrycarter,
this is a bit of the result when i print(terms.encode()):
b' 2 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0.6684459764580090 -07 0.3603178002233933 -06\n'
b' 3 0 2 -4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.2383757728520679 -07 0.9861749707454420 -07\n'
b' 4 0 4 -6 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.2193692495097233 -07 -0.8959173003201546 -07\n'
b' 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.0000000000000000 +00 0.1017891898227051 -03\n'
b' 2 0 3 -5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.4236543085970792 -07 -0.8775084424897674 -08\n'
b' 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.0000000000000000 +00 0.4702795245810685 -04\n'
b' 2 0 3 -5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.5710471800210820 -09 -0.1800837750117577 -08\n'
b' 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.0000000000000000 +00 -0.5421827377115325 -06\n'
b' 2 0 3 -5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.7074507338012408 -10 0.1742474656298139 -10\n'
b' 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.0000000000000000 +00 -0.2508633795522544 -07\n'
b' 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.0000000000000000 +00 0.4575014479216901 -09\n'
b' 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.0000000000000000 +00 0.5208591612817609 -11\n'
b' 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.0000000000000000 +00 -0.1737141639583644 -12'