def countdown(self):
for k in range(5, -1, -1):
countdown_text = TexMobject(str(k))
countdown_text.scale(1.5)
countdown_text.set_color(YELLOW)
countdown_text.to_corner(RIGHT+UP)
self.add(countdown_text)
self.wait()
self.remove(countdown_text)
def setup(self):
pos_axis = NumberLine(x_min=-4.5, x_max=2.5, color=WHITE)
pos_axis.rotate(np.pi / 2)
pos_axis.add_tip()
time_axis = NumberLine(x_min=0, x_max=9.5, color=WHITE)
time_axis.add_tip()
vec = pos_axis.number_to_point(0) - time_axis.number_to_point(0)
time_axis.shift(vec)
pos_text = TextMobject("位置")
pos_text.next_to(pos_axis.number_to_point(2.5), LEFT)
time_text = TextMobject("时间")
time_text.next_to(time_axis.number_to_point(9.5), DOWN)
axes_group = VGroup(pos_axis, time_axis, pos_text, time_text)
axes_group.center()
title_pq = TexMobject("P_4", "570", "Q_4")
title_pq.scale(1.5)
title_pq.to_corner(UP + RIGHT)
for part, color in zip(title_pq, [ORANGE, BLACK, GREEN]):
part.set_color(color)
r_arrow = TexMobject("\\rightarrow")
l_arrow = TexMobject("\\leftarrow")
for arrow in (r_arrow, l_arrow):
arrow.scale(1.5)
arrow.move_to(title_pq[1])
sequence_p, sequence_q = sequences = ["UDUUDUDD", "DDUDDUDD"]
colors = [ORANGE, GREEN]
walk_p, walk_q = walks = [
RandomWalk1DArrow(sequence, up_color = color, down_color = color) \
.move_start_to(pos_axis.number_to_point(0))
for sequence, color in zip(sequences, colors)
]
parts_p, parts_q = [walk.split_at(3) for walk in walks]
self.axes_group = axes_group
self.title_pq = title_pq
self.walk_p = walk_p
self.walk_q = walk_q
self.parts_p = parts_p
self.parts_q = parts_q
self.r_arrow = r_arrow
self.l_arrow = l_arrow
