# Kepler's Laws.py
# plots the orbit of a planet in an eccentric orbit to illustrate
# the sweeping out of equal areas in equal times, with sun at focus
# The eccentricity of the orbit is random and determined by the initial velocity
# program uses normalised units (G =1)
# program by Peter Borcherds, University of Birmingham, England
from vpython import *
from random import random
from IPython import display
import pandas as pd
def MonthStep(time, offset=20, whole=1): # mark the end of each "month"
global ccolor # have to make it global, since label uses it before it is updated
if whole:
Ltext = str(int(time * 2 + dt)) # end of 'month', printing twice time gives about 12 'months' in 'year'
else:
Ltext = duration + str(time * 2) + ' "months"\n Initial speed: ' + str(round(speed, 3))
ccolor = color.white
label(pos=planet.pos, text=Ltext, color=ccolor,
xoffset=offset * planet.pos.x, yoffset=offset * planet.pos.y)
ccolor = (0.5 * (1 + random()), random(), random()) # randomise colour of radial vector
return ccolor
scene = display(title="Kepler's law of equal areas", width=1000, height=1000, range=3.2)
duration = 'Period: '
sun = sphere(color=color.yellow, radius=0.1) # motion of sun is ignored (or centre of mass coordinates)
scale = 1.0
poss = vector(0, scale, 0)
planet = sphere(pos=poss, color=color.cyan, radius=0.02)
while 1:
velocity = -vector(0.7 + 0.5 * random(), 0, 0) # gives a satisfactory range of eccentricities
##velocity = -vector(0.984,0,0) # gives period of 12.0 "months"
speed = mag(velocity)
steps = 20
dt = 0.5 / float(steps)
step = 0
time = 0
ccolor = color.white
oldpos = vector(planet.pos)
ccolor = MonthStep(time)
curve(pos=[sun.pos, planet.pos], color=ccolor)
while not (oldpos.x > 0 and planet.pos.x < 0):
rate(steps * 2) # keep rate down so that development of orbit can be followed
time += dt
oldpos = vector(planet.pos) # construction vector(planet.pos) makes oldpos a varible in its own right
# oldpos = planet.pos makes "oldposs" point to "planet.pos"
# oldposs = planet.pos[:] does not work, because vector does not permit slicing
denom = mag(planet.pos) ** 3
velocity -= planet.pos * dt / denom # inverse square law; force points toward sun
planet.pos += velocity * dt
# plot orbit
curve(pos=[oldpos, planet.pos], color=color.red)
step += 1
if step == steps:
step = 0
ccolor = MonthStep(time)
curve(pos=[sun.pos, planet.pos], color=color.white)
else:
# plot radius vector
curve(pos=[sun.pos, planet.pos], color=ccolor)
if scene.kb.keys:
print
"key pressed"
duration = 'Duration: '
break
MonthStep(time, 50, 0)
label(pos=(2.5, -2.5, 0), text='Click for another orbit')
scene.mouse.getclick()
for obj in scene.objects:
if obj is sun or obj is planet: continue
obj.visible = 0 # clear the screen to do it again
I copied Kepler's Laws code in google and compiled it on pycharm.
But there is an error that
scene = display(title="Kepler's law of equal areas", width=1000, height=1000, range=3.2)
TypeError: 'module' object is not callable
I found some information on google that "pandas" library can improve this error so I tried it but I can't improve this error.
What should I do?
Replace "display" with "canvas", which is the correct name of this entity.