def construct(self):
axes = Axes(x_min=-0.5,
x_max=6.5,
y_min=-0.5,
y_max=6.5,
color=GREY,
number_line_config={"tick_size": 0})
axes.center()
wallis_rects_5 = WallisRectangles(rect_colors=[
"#FF0000", "#FF8000", "#FFFF00", "#00FF00", "#0080FF"
],
order=5)
wallis_rects_5.move_corner_to(axes.coords_to_point(0, 0))
quarter_circle = Sector(
outer_radius=wallis_rects_5.get_height(),
stroke_color=GREY,
stroke_width=5.70,
fill_opacity=0,
)
quarter_circle.move_arc_center_to(wallis_rects_5.get_bottom_left())
self.add(wallis_rects_5, axes, quarter_circle)
order = wallis_rects_5.get_order()
inner_corners = [
rect.get_critical_point(UP + RIGHT)
for rect in wallis_rects_5.get_layer(3)
]
outer_corners = [
rect.get_critical_point(UP + RIGHT)
for rect in wallis_rects_5.get_layer(4)
]
inner_dots = VGroup(*[
Dot(corner, color=PINK, stroke_width=2, stroke_color=BLACK)
for corner in inner_corners
])
outer_dots = VGroup(*[
Dot(corner, stroke_width=2, stroke_color=BLACK)
for corner in outer_corners
])
inner_texts = VGroup(*[
TexMobject("(s_%d, s_%d)" % (order - k, k)) \
.scale(0.8) \
.set_color(PINK) \
.next_to(dot, LEFT+DOWN, buff = 0.05)
for k, dot in zip(range(1, len(inner_dots) + 1), inner_dots)
])
outer_texts = VGroup(*[
TexMobject("(s_%d, s_%d)" % (order + 1 - k, k)) \
.scale(0.8) \
.set_color(WHITE) \
.next_to(dot, RIGHT+UP, buff = 0.05)
for k, dot in zip(range(1, len(outer_dots) + 1), outer_dots)
])
self.add(inner_dots, outer_dots, inner_texts, outer_texts)
self.wait()
def __init__(self, mobject_or_point, **kwargs):
digest_config(self, kwargs)
big_dot = Dot(
radius=FRAME_X_RADIUS + FRAME_Y_RADIUS,
stroke_width=0,
fill_color=self.color,
fill_opacity=0,
)
little_dot = Dot(radius=0)
little_dot.set_fill(self.color, opacity=self.opacity)
little_dot.move_to(mobject_or_point)
Transform.__init__(self, big_dot, little_dot, **kwargs)
def generate_points(self):
self.line_group = VGroup()
self.dot_group = VGroup()
vertices = self.generate_vertices_from_string(self.walk_string)
for k in range(len(vertices) - 1):
line = Line(vertices[k],
vertices[k + 1],
color=self.get_mob_color_by_number(k))
dot = Dot(vertices[k], color=self.dot_color)
self.line_group.add(line)
self.dot_group.add(dot)
self.dot_group.add(Dot(vertices[-1], color=self.dot_color))
self.add(self.line_group, self.dot_group)
self.horizontally_center()
def increment(self, run_time_per_anim=1):
moving_dot = Dot(
self.counting_dot_starting_position,
radius=self.count_dot_starting_radius,
color=self.digit_place_colors[0],
)
moving_dot.generate_target()
moving_dot.set_fill(opacity=0)
kwargs = {
"run_time": run_time_per_anim
}
continue_rolling_over = True
first_move = True
place = 0
while continue_rolling_over:
added_anims = []
if first_move:
added_anims += self.get_digit_increment_animations()
first_move = False
moving_dot.target.replace(
self.dot_template_iterators[place].next()
)
self.play(MoveToTarget(moving_dot), *added_anims, **kwargs)
self.curr_configurations[place].add(moving_dot)
if len(self.curr_configurations[place].split()) == self.get_place_max(place):
full_configuration = self.curr_configurations[place]
self.curr_configurations[place] = VGroup()
place += 1
center = full_configuration.get_center_of_mass()
radius = 0.6 * max(
full_configuration.get_width(),
full_configuration.get_height(),
)
circle = Circle(
radius=radius,
stroke_width=0,
fill_color=self.digit_place_colors[place],
fill_opacity=0.5,
)
circle.move_to(center)
moving_dot = VGroup(circle, full_configuration)
moving_dot.generate_target()
moving_dot[0].set_fill(opacity=0)
else:
continue_rolling_over = False
def get_dot_template(self, place):
# This should be replaced for non-base-10 counting scenes
dots = VGroup(*[
Dot(
point,
radius=0.25,
fill_opacity=0,
stroke_width=2,
stroke_color=WHITE,
) for point in self.get_template_configuration(place)
])
dots.scale_to_fit_height(self.dot_configuration_height)
return dots
def __init__(self, mobject_or_point, **kwargs):
digest_config(self, kwargs)
big_dot = Dot(
radius=FRAME_X_RADIUS + FRAME_Y_RADIUS,
stroke_width=0,
fill_color=self.color,
fill_opacity=0,
)
little_dot = Dot(radius=0)
little_dot.set_fill(self.color, opacity=self.opacity)
little_dot.move_to(mobject_or_point)
Transform.__init__(self, big_dot, little_dot, **kwargs)
def show_ghost_movement(self, vector):
if isinstance(vector, Arrow):
vector = vector.get_end() - vector.get_start()
elif len(vector) == 2:
vector = np.append(np.array(vector), 0.0)
x_max = int(FRAME_X_RADIUS + abs(vector[0]))
y_max = int(FRAME_Y_RADIUS + abs(vector[1]))
dots = VMobject(*[
Dot(x * RIGHT + y * UP) for x in range(-x_max, x_max)
for y in range(-y_max, y_max)
])
dots.set_fill(BLACK, opacity=0)
dots_halfway = dots.copy().shift(vector / 2).set_fill(WHITE, 1)
dots_end = dots.copy().shift(vector)
self.play(Transform(dots, dots_halfway, rate_func=rush_into))
self.play(Transform(dots, dots_end, rate_func=rush_from))
self.remove(dots)
def construct(self):
# Setup
axes_group = self.axes_group
pos_axis, time_axis = axes_group[:2]
title_pq = self.title_pq
walk_q = self.walk_q
parts_q = self.parts_q
l_arrow = self.l_arrow
self.add(axes_group, title_pq, walk_q, l_arrow)
walk_q_copy = walk_q.copy()
# Q_4 -> P_4
steps_qp = VGroup(*[
TextMobject(text) for text in [
"1. 找到路径终点的位置坐标$h$", "2. 找到最晚一次穿过$\\frac{h}{2}$的时刻",
"3. 在这个时刻上进行分割", "4. 将第一段水平翻转", "5. 拼接两个片段"
]
])
for step in steps_qp:
step.set_color(YELLOW)
step.add_background_rectangle()
step1_qp, step2_qp, step3_qp, step4_qp, step5_qp = steps_qp
# 1. Find the endpoint
step1_qp.next_to(time_axis.number_to_point(4.5), UP)
end_horiz_line = DashedLine(LEFT_SIDE, RIGHT_SIDE, color=YELLOW)
end_horiz_line.move_to(pos_axis.number_to_point(-4))
end_horiz_line.horizontally_center()
end_brace_line = DashedLine(time_axis.number_to_point(8),
walk_q.get_end_point())
end_brace = Brace(end_brace_line, direction=RIGHT, color=YELLOW)
h = TexMobject("h").set_color(YELLOW)
end_brace.put_at_tip(h)
self.play(Write(step1_qp), ShowCreation(end_horiz_line), run_time=1)
self.play(GrowFromCenter(end_brace), GrowFromCenter(h))
self.wait(1.5)
self.play(FadeOut(step1_qp))
# 2. Find the last time it GOES THROUGH half its final value
half_point = walk_q.get_arrow_end_point(3)
step2_qp.next_to(time_axis.number_to_point(4.5), UP)
half_horiz_line = end_horiz_line.copy().shift(2 * UP)
half_brace_line = DashedLine(time_axis.number_to_point(4), half_point)
half_brace = Brace(half_brace_line, direction=RIGHT, color=YELLOW)
half_h = TexMobject("\\frac{h}{2}").set_color(YELLOW)
half_brace.put_at_tip(half_h)
half_dot = Dot(half_point, color=YELLOW)
self.play(FadeIn(step2_qp), run_time=1)
self.wait(0.5)
self.play(
ReplacementTransform(end_brace, half_brace),
ReplacementTransform(end_horiz_line, half_horiz_line),
ReplacementTransform(h, half_h[0]),
Write(half_h[1:]),
)
self.play(DrawBorderThenFill(half_dot))
self.wait(1.5)
self.play(
FadeOut(VGroup(step2_qp, half_horiz_line, half_brace, half_h)))
# 3. Split
vert_line = DashedLine(2.5 * UP, 2.5 * DOWN, color=YELLOW)
vert_line.move_to(half_point)
step3_qp.next_to(vert_line, UP)
left_part_q, right_part_q = parts_q
self.play(ShowCreation(vert_line), Write(step3_qp), run_time=1)
self.play(
FadeOut(half_dot),
left_part_q.shift,
0.5 * DOWN + 0.5 * LEFT,
right_part_q.shift,
0.5 * UP + 0.5 * RIGHT,
)
self.wait(1.5)
self.play(FadeOut(vert_line), FadeOut(step3_qp))
# 4. Flip the first segment horizontally
flip_axis = DashedLine(2 * UP, 2 * DOWN, color=GREY)
flip_axis.move_to(left_part_q)
step4_qp.next_to(flip_axis, DOWN)
self.play(
ShowCreation(flip_axis),
Write(step4_qp),
run_time=1,
)
self.play(
left_part_q.flip,
Animation(flip_axis),
)
self.wait(1.5)
self.play(FadeOut(step4_qp), FadeOut(flip_axis))
# 5. Put the pieces together
step5_qp.shift(2.5 * DOWN)
flip_arrow_anims = walk_q.get_flip_arrows_animation(3, color=ORANGE)
self.play(Write(step5_qp), run_time=1)
self.wait(0.5)
self.play(flip_arrow_anims, right_part_q.set_color, ORANGE)
self.wait(0.5)
self.play(
left_part_q.shift,
2.5 * UP + 0.5 * RIGHT,
right_part_q.shift,
3.5 * UP + 0.5 * LEFT,
Animation(step5_qp),
)
self.wait(0.5)
self.play(FadeOut(step5_qp))
self.wait(1.5)
# Now Reset
self.play(FadeOut(walk_q))
self.play(FadeIn(walk_q_copy))
self.wait()
def construct(self):
# Setup
axes_group = self.axes_group
title_pq = self.title_pq
walk_p = self.walk_p
parts_p = self.parts_p
r_arrow = self.r_arrow
self.add(axes_group, title_pq, walk_p, r_arrow)
walk_p_copy = walk_p.copy()
# P_4 -> Q_4
steps_pq = VGroup(*[
TextMobject(text) for text in [
"1. 第一步是沿着正方向走的", "2. 找到第一次到达最大值的时刻", "3. 在这个时刻上进行分割",
"4. 将第一段水平翻转", "5. 拼接两个片段"
]
])
for step in steps_pq:
step.set_color(YELLOW)
step.add_background_rectangle()
step1_pq, step2_pq, step3_pq, step4_pq, step5_pq = steps_pq
# 1. Check the first step of the walk
step1_circle = Circle(color=YELLOW)
first_arrow = walk_p.get_arrow_by_number(0)
step1_circle.surround(first_arrow)
step1_pq.next_to(step1_circle, RIGHT + DOWN)
self.play(ShowCreation(step1_circle), Write(step1_pq), run_time=1)
self.wait(1.5)
self.play(FadeOut(step1_circle), FadeOut(step1_pq))
# 2. Find the first time it reaches the maximum
peak = walk_p.get_arrow_end_point(3)
horiz_line = DashedLine(2.5 * LEFT, 2.5 * RIGHT, color=YELLOW)
horiz_line.move_to(peak)
dot = Dot(color=YELLOW)
dot.move_to(peak)
step2_pq.next_to(horiz_line, UP)
self.play(ShowCreation(horiz_line),
DrawBorderThenFill(dot),
Write(step2_pq),
run_time=1)
self.wait(1.5)
self.play(FadeOut(horiz_line), FadeOut(step2_pq))
# 3. Split
vert_line = DashedLine(2.5 * UP, 2.5 * DOWN, color=YELLOW)
vert_line.move_to(peak)
step3_pq.next_to(vert_line, DOWN)
left_part_p, right_part_p = parts_p
self.play(ShowCreation(vert_line), Write(step3_pq), run_time=1)
self.play(
FadeOut(dot),
left_part_p.shift,
0.5 * DOWN + 0.5 * LEFT,
right_part_p.shift,
DOWN + 0.5 * RIGHT,
)
self.wait(1.5)
self.play(FadeOut(vert_line), FadeOut(step3_pq))
# 4. Flip the first segment horizontally
flip_axis = DashedLine(2 * UP, 2 * DOWN, color=GREY)
flip_axis.move_to(left_part_p)
step4_pq.next_to(flip_axis, DOWN)
self.play(
ShowCreation(flip_axis),
Write(step4_pq),
run_time=1,
)
self.play(
left_part_p.flip,
Animation(flip_axis),
)
self.wait(1.5)
self.play(FadeOut(step4_pq), FadeOut(flip_axis))
# 5. Put the pieces together
step5_pq.move_to(dot)
flip_arrow_anims = walk_p.get_flip_arrows_animation(3, color=GREEN)
self.play(Write(step5_pq), run_time=1)
self.wait(0.5)
self.play(flip_arrow_anims, right_part_p.set_color, GREEN)
self.wait(0.5)
self.play(
left_part_p.shift,
1.5 * DOWN + 0.5 * RIGHT,
right_part_p.shift,
3 * DOWN + 0.5 * LEFT,
Animation(step5_pq),
)
self.wait(0.5)
self.play(FadeOut(step5_pq))
self.wait(1.5)
# Now Reset
self.play(FadeOut(walk_p))
self.play(FadeIn(walk_p_copy))
self.wait()
def label(self, point_or_points):
if len(point_or_points.shape) == 1:
self.add(Dot(point_or_points, color=RED))
else:
for point in point_or_points:
self.add(Dot(point, color=RED))