-
Notifications
You must be signed in to change notification settings - Fork 1
/
__algorithms.py
439 lines (401 loc) · 14.8 KB
/
__algorithms.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
# PROJECT JULY-SEPTEMBRE 2019
# SOLVING THE N-BODIES PROBLEM / CLASSES
# By Enguerran VIDAL
# This file contains the different kind of engines used further in main.py to
# calculate the state of our NBody problem at the next time-step.
###############################################################
# IMPORTS #
###############################################################
#-----------------MODULES
import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
import random
import matplotlib.animation
#-----------------PYTHON FILES
from __constants_conversions import*
from __functions import*
###############################################################
# CLASSES #
###############################################################
#------------OBJECTS
class Object():
''' A class creating a point in space with mass '''
def __init__(self,mass,position,speed,index=None):
self.mass=mass
self.position=position
self.speed=speed
self.index=index
#------------SUB ALGORITHMS
class OctTree():
''' A class creating an object permiting the division of 3D space in subdividing cubes
to finally use it to compute a Barnes-Hut algorithm ( solving the N-bodies problem ).'''
def __init__(self,objects,a,b,c,d,e,f):
self.objects=objects
self.n_objects=len(self.objects)
self.children=[None,None,None,None,None,None,None,None]
self.a=a
self.b=b
self.c=c
self.d=d
self.e=e
self.f=f
self.m_center()
self.build()
def build(self):
if self.n_objects>1:
TNW=[]
TNE=[]
TSW=[]
TSE=[]
BNW=[]
BNE=[]
BSW=[]
BSE=[]
for i in range(self.n_objects):
m1=(self.a+self.b)/2
m2=(self.c+self.d)/2
m3=(self.e+self.f)/2
if self.objects[i].position[0]>m1:
if self.objects[i].position[1]>m2:
if self.objects[i].position[2]>m3:
TNE.append(self.objects[i])
else:
BNE.append(self.objects[i])
else :
if self.objects[i].position[2]>m3:
TSE.append(self.objects[i])
else:
BSE.append(self.objects[i])
else :
if self.objects[i].position[1]>m2:
if self.objects[i].position[2]>m3:
TNW.append(self.objects[i])
else:
BNW.append(self.objects[i])
else :
if self.objects[i].position[2]>m3:
TSW.append(self.objects[i])
else:
BSW.append(self.objects[i])
self.children[0]=OctTree(TNW,m1,self.b,self.c,m2,self.e,m3)
self.children[1]=OctTree(TNE,self.a,m1,self.c,m2,self.e,m3)
self.children[2]=OctTree(TSW,m1,self.b,m2,self.d,self.e,m3)
self.children[3]=OctTree(TSE,self.a,m1,m2,self.d,self.e,m3)
self.children[4]=OctTree(BNW,m1,self.b,self.c,m2,m3,self.f)
self.children[5]=OctTree(BNE,self.a,m1,self.c,m2,m3,self.f)
self.children[6]=OctTree(BSW,m1,self.b,m2,self.d,m3,self.f)
self.children[7]=OctTree(BSE,self.a,m1,m2,self.d,m3,self.f)
def m_center(self):
if self.n_objects>0:
xc=0
yc=0
zc=0
m=0
for i in range(self.n_objects):
xc=xc+self.objects[i].mass*self.objects[i].position[0]
yc=yc+self.objects[i].mass*self.objects[i].position[1]
yc=yc+self.objects[i].mass*self.objects[i].position[2]
m=m+self.objects[i].mass
self.mass_center=[xc/m,yc/m,zc/m]
self.mass=m
def forces(self,objectI,theta):
if self.n_objects>0:
width=self.a-self.b
d=points_distance_3D(self.mass_center,objectI.position)
if d!=0:
t=width/d
if t < theta or self.children[0]==None:
v=points_vector_3D(objectI.position,self.mass_center)
m=self.mass
a=(constant('G')*m*v)/(d**3)
return a
else:
a1=self.children[0].forces(objectI,theta)
a2=self.children[1].forces(objectI,theta)
a3=self.children[2].forces(objectI,theta)
a4=self.children[3].forces(objectI,theta)
a5=self.children[4].forces(objectI,theta)
a6=self.children[5].forces(objectI,theta)
a7=self.children[6].forces(objectI,theta)
a8=self.children[7].forces(objectI,theta)
return a1+a2+a3+a4
else:
return np.array([0,0,0])
else:
return np.array([0,0,0])
class QuadTree():
''' A class creating an object permiting the division of 2D space in subdividing squares
to finally use it to compute a Barnes-Hut algorithm ( solving the N-bodies problem ).'''
def __init__(self,objects,a,b,c,d):
self.objects=objects
self.n_objects=len(self.objects)
self.children=[None,None,None,None]
self.a=a
self.b=b
self.c=c
self.d=d
self.m_center()
self.build()
def build(self):
if self.n_objects>1:
NW=[]
NE=[]
SW=[]
SE=[]
for i in range(self.n_objects):
m1=(self.a+self.b)/2
m2=(self.c+self.d)/2
if self.objects[i].position[0]>m1:
if self.objects[i].position[1]>m2:
NE.append(self.objects[i])
else :
SE.append(self.objects[i])
else :
if self.objects[i].position[1]>m2:
NW.append(self.objects[i])
else :
SW.append(self.objects[i])
self.children[0]=QuadTree(NW,m1,self.b,self.c,m2)
self.children[1]=QuadTree(NE,self.a,m1,self.c,m2)
self.children[2]=QuadTree(SW,m1,self.b,m2,self.d)
self.children[3]=QuadTree(SE,self.a,m1,m2,self.d)
def m_center(self):
if self.n_objects>0:
xc=0
yc=0
m=0
for i in range(self.n_objects):
xc=xc+self.objects[i].mass*self.objects[i].position[0]
yc=yc+self.objects[i].mass*self.objects[i].position[1]
m=m+self.objects[i].mass
self.mass_center=[xc/m,yc/m]
self.mass=m
def forces(self,objectI,theta):
if self.n_objects>0:
width=self.a-self.b
d=points_distance_2D(self.mass_center,objectI.position)
if d!=0:
t=width/d
if t < theta or self.children[0]==None:
v=points_vector_2D(objectI.position,self.mass_center)
m=self.mass
a=(constant('G')*m*v)/(d**3)
return a
else:
a1=self.children[0].forces(objectI,theta)
a2=self.children[1].forces(objectI,theta)
a3=self.children[2].forces(objectI,theta)
a4=self.children[3].forces(objectI,theta)
return a1+a2+a3+a4
else:
return np.array([0,0])
else:
return np.array([0,0])
#----------------SIMULATION_ALGORITHMS
class BHut_Algorithm_3D():
''' Class using the Octree class above in order to solve the N-Bodies problem in 3D using the Barnes-Hut Algorithm'''
def __init__(self,frame,theta):
self.frame=frame
self.theta=theta
def objects_positions(self,Objects):
X=np.array([])
Y=np.array([])
Z=np.array([])
n=len(Objects)
for i in range(n):
x=Objects[i].position[0]
y=Objects[i].position[1]
z=Objects[i].position[2]
X=np.append(X,x)
Y=np.append(Y,y)
Z=np.append(Z,z)
return X,Y,Z
def update_frame(new_frame):
self.frame=new_frame
def compute(self,Objects):
new_positions=[]
new_speeds=[]
n=len(Objects)
X,Y,Z=self.objects_positions(Objects)
m=max([array_max_abs(X),array_max_abs(Y),array_max_abs(Z)])
Q=OctTree(Objects,m,-m,m,-m,m,-m)
for i in range(n):
objectI=Objects[i]
acceleration=Q.forces(objectI,self.theta)
U=np.array([objectI.position,objectI.speed])
New_U=U+self.frame*np.array([U[1],acceleration])
new_positions.append(New_U[0])
new_speeds.append(New_U[1])
X=np.array([])
Y=np.array([])
Z=np.array([])
dX=np.array([])
dY=np.array([])
dZ=np.array([])
for i in range(n):
x=new_positions[i][0]
y=new_positions[i][1]
z=new_positions[i][2]
dx=new_speeds[i][0]
dy=new_speeds[i][1]
dz=new_speeds[i][2]
X=np.append(X,x)
Y=np.append(Y,y)
Z=np.append(Z,z)
dX=np.append(dX,dx)
dY=np.append(dY,dy)
dZ=np.append(dZ,dz)
return X,Y,Z,dX,dY,dZ
class BHut_Algorithm_2D():
''' Class using the Quadtree class above in order to solve the N-Bodies problem in 2D using the Barnes-Hut Algorithm'''
def __init__(self,frame,theta):
self.frame=frame
self.theta=theta
def objects_positions(self,Objects):
X=np.array([])
Y=np.array([])
n=len(Objects)
for i in range(n):
x=Objects[i].position[0]
y=Objects[i].position[1]
X=np.append(X,x)
Y=np.append(Y,y)
return X,Y
def update_frame(new_frame):
self.frame=new_frame
def compute(self,Objects):
new_positions=[]
new_speeds=[]
X,Y=self.objects_positions(Objects)
m=max(array_max_abs(X),array_max_abs(Y))
Q=QuadTree(Objects,m,-m,m,-m)
n=len(Objects)
for i in range(n):
objectI=Objects[i]
acceleration=Q.forces(objectI,self.theta)
U=np.array([objectI.position,objectI.speed])
New_U=U+self.frame*np.array([U[1],acceleration])
new_positions.append(New_U[0])
new_speeds.append(New_U[1])
X=np.array([])
Y=np.array([])
dX=np.array([])
dY=np.array([])
for i in range(n):
x=new_positions[i][0]
y=new_positions[i][1]
dx=new_speeds[i][0]
dy=new_speeds[i][1]
X=np.append(X,x)
Y=np.append(Y,y)
dX=np.append(dX,dx)
dY=np.append(dY,dy)
return X,Y,dX,dY
class Standard_Algorithm_3D():
''' Class solving the N-Bodies problem in 3D using a regular integrator algorithm without any real approximations.'''
def __init__(self,frame):
self.frame=frame
def objects_positions(self,Objects):
X=np.array([])
Y=np.array([])
Z=np.array([])
n=len(Objects)
for i in range(n):
x=Objects[i].position[0]
y=Objects[i].position[1]
z=Objects[i].position[2]
X=np.append(X,x)
Y=np.append(Y,y)
Z=np.append(Z,z)
return X,Y,Z
def update_frame(new_frame):
self.frame=new_frame
def compute(self,Objects):
new_positions=[]
new_speeds=[]
n=len(Objects)
for i in range(n):
objectI=Objects[i]
acceleration=0
for j in range(n):
if j!=i:
objectJ=Objects[j]
m=objectJ.mass
d=object_distance_3D(objectI,objectJ)
v=object_vector_3D(objectI,objectJ)
a=(constant('G')*m*v)/(d**3)
acceleration=acceleration+a
U=np.array([objectI.position,objectI.speed])
New_U=U+self.frame*np.array([U[1],acceleration])
new_positions.append(New_U[0])
new_speeds.append(New_U[1])
X=np.array([])
Y=np.array([])
Z=np.array([])
dX=np.array([])
dY=np.array([])
dZ=np.array([])
for i in range(n):
x=new_positions[i][0]
y=new_positions[i][1]
z=new_positions[i][2]
dx=new_speeds[i][0]
dy=new_speeds[i][1]
dz=new_speeds[i][2]
X=np.append(X,x)
Y=np.append(Y,y)
Z=np.append(Z,z)
dX=np.append(dX,dx)
dY=np.append(dY,dy)
dZ=np.append(dZ,dz)
return X,Y,Z,dX,dY,dZ
class Standard_Algorithm_2D():
'''Class solving the N-Bodies problem in 2D using a regular integrator algorithm without any real approximations.'''
def __init__(self,frame):
self.frame=frame
def objects_positions(self,Objects):
X=np.array([])
Y=np.array([])
n=len(Objects)
for i in range(n):
x=Objects[i].position[0]
y=Objects[i].position[1]
X=np.append(X,x)
Y=np.append(Y,y)
return X,Y
def update_frame(new_frame):
self.frame=new_frame
def compute(self,Objects):
new_positions=[]
new_speeds=[]
n=len(Objects)
for i in range(n):
objectI=Objects[i]
acceleration=0
for j in range(n):
if j!=i:
objectJ=Objects[j]
m=objectJ.mass
d=object_distance_2D(objectI,objectJ)
v=object_vector_2D(objectI,objectJ)
a=(constant('G')*m*v)/(d**3)
acceleration=acceleration+a
U=np.array([objectI.position,objectI.speed])
New_U=U+self.frame*np.array([U[1],acceleration])
new_positions.append(New_U[0])
new_speeds.append(New_U[1])
X=[]
Y=[]
dX=[]
dY=[]
for i in range(self.n_objects):
x=new_positions[i][0]
y=new_positions[i][1]
dx=new_speeds[i][0]
dy=new_speeds[i][1]
X.append(x)
Y.append(y)
dX.append(dx)
dY.append(dy)
return X,Y,dX,dY