"""This module is part of Swampy, a suite of programs available from allendowney.com/swampy. Copyright 2011 Allen B. Downey Distributed under the GNU General Public License at gnu.org/licenses/gpl.html. """ import math import random import time from Tkinter import END from World import World, Animal, MyThread class AmoebaWorld(World): """A microscope slide where Amoebas trace parametric equations. Attributes: delay: time step in ms """ def __init__(self, interactive=False, delay=100): World.__init__(self) self.delay = delay self.title('AmoebaWorld') self.running = False self.make_canvas() if interactive: self.make_control_panel() def make_canvas(self, low=-10, high=10): """Makes the canvas and draws the grid marks.""" self.col() self.ca_width = 400 self.ca_height = 400 self.canvas = self.ca(width=self.ca_width, height=self.ca_height, bg='white', scale=[20,20]) # draw the grid d = {True:'', False:'.'} xmin, xmax = low, high ymin, ymax = low, high for x in range(xmin, xmax+1, 1): self.canvas.line([[x, ymin], [x, ymax]], dash=d[x==0]) for y in range(ymin, ymax+1, 1): self.canvas.line([[xmin, y], [xmax, y]], dash=d[y==0]) def make_control_panel(self): """Makes the buttons and input fields.""" # buttons self.row() self.bu(text='Run', command=self.run) self.bu(text='Stop', command=self.stop) self.bu(text='Clear', command=self.clear) self.bu(text='Quit', command=self.quit) self.endrow() # end time entry self.row([0,1,0], pady=5) self.la(text='end time') self.en_end = self.en(width=5, text='10') self.la(text='seconds') self.endrow() # entries for x(t) and y(t) self.en_x_t = self.make_entry('x(t) = ') self.en_y_t = self.make_entry('y(t) = ') def make_entry(self, label): """Makes an entry with the given label.""" self.row([0,1,0], pady=5) self.la(text=label) entry = self.en(width=5, text=' t') self.endrow() return entry def set_entry(self, entry, text): """Sets the contents of an entry widget.""" entry.delete(0, END) entry.insert(END, text) def set_end_time(self, text): """Sets the contents of the end time entry widget.""" self.set_entry(self.en_end, text) def set_x_t(self, text): """Sets the contents of the x_t entry widget.""" self.set_entry(self.en_x_t, text) def set_y_t(self, text): """Sets the contents of the y_t entry widget.""" self.set_entry(self.en_y_t, text) def run(self): """Runs the amoebas in real time.""" if self.running: # after_cancel pass self.running = True self.clear() # find out how long to run end = self.en_end.get() try: self.end = float(eval(end)) except: print 'End time must be a numeric expression.' return self.start_time = time.time() self.after(0, self.step) def step(self): """Advance the Amoebas one step.""" if not self.exists or not self.running: return xexpr = self.en_x_t.get() yexpr = self.en_y_t.get() # see how much time has elapsed and evaluate x(t) and y(t) t = time.time() - self.start_time if t> self.end: return x = eval(xexpr) y = eval(yexpr) print 't = %.1f x = %.1f y = %.1f' % (t, x, y) for amoeba in self.animals: amoeba.move(x, y) # schedule the next step self.after(self.delay, self.step) def clear(self): """Clears the amoebas and slime (but not the grid marks).""" for animal in self.animals: animal.undraw() self.canvas.delete('slime') class Amoeba(Animal): """A soft, round animal that lives in AmoebaWorld Attributes: size: radius in hash marks color1 = color of the cell color2 = color of the nucleus """ def __init__(self, world=None): Animal.__init__(self, world) # size and color self.size = 0.5 self.color1 = 'violet' self.color2 = 'medium orchid' self.tag = 'Amoeba%d' % id(self) def move(self, x, y): """Moves the amoeba and redraws.""" self.x = x self.y = y self.redraw() def draw(self): """Draws the Amoeba.""" # thetas is the sequence of angles used to compute the perimeter thetas = range(0, 360, 30) coords = self.poly_coords(self.x, self.y, thetas, self.size) slime = 'lavender' # draw the slime outline which will be left behind self.world.canvas.polygon(coords, fill=slime, outline=slime, tags='slime') # draw the outer perimeter self.world.canvas.polygon(coords, fill=self.color1, outline=self.color2, tags=self.tag) # draw the perimeter of the nucleus coords = self.poly_coords(self.x, self.y, thetas, self.size/2) self.world.canvas.polygon(coords, fill=self.color2, outline=self.color1, tags=self.tag) def poly_coords(self, x, y, thetas, size): """Computes coordinates of a polygon with random variation. Args: x, y: center point thetas: sequence of angles size: minimum radius; actual radius is up to 2x bigger """ rs = [size+random.uniform(0, size) for theta in thetas] coords = [self.polar(x, y, r, theta) for (r, theta) in zip(rs, thetas)] return coords if __name__ == '__main__': # create the GUI world = AmoebaWorld(interactive=True) world.set_end_time('2 * math.pi') world.set_x_t('10 * math.cos(t)') world.set_y_t('10 * math.sin(t)') # create the amoeba amoeba = Amoeba() # wait for the user to do something world.mainloop()

AltStyle によって変換されたページ (->オリジナル) /