Halfway through dot products

This commit is contained in:
Grant Sanderson
2016-08-19 15:54:16 -07:00
parent fa6fa38a00
commit f0bd594428
4 changed files with 557 additions and 7 deletions

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@ -19,11 +19,13 @@ from mobject.vectorized_mobject import *
from eola.matrix import *
from eola.two_d_space import *
from eola.footnote2 import TwoDTo1DTransformWithDots
from ka_playgrounds.circuits import Resistor, Source, LongResistor
V_COLOR = YELLOW
W_COLOR = MAROON_B
SUM_COLOR = PINK
def get_projection(stable_vector, vector_to_project):
dot_product = np.dot(*[
@ -633,11 +635,552 @@ class LurkingQuestion(TeacherStudentsScene):
everything
))
class Introduce2Dto1DLinearTransformations(LinearTransformationScene):
class TwoDToOneDScene(LinearTransformationScene):
CONFIG = {
"include_background_plane" : False,
"foreground_plane_kwargs" : {
"x_radius" : SPACE_WIDTH,
"y_radius" : SPACE_HEIGHT,
"secondary_line_ratio" : 1
},
"t_matrix" : [[2, 0], [1, 0]]
}
def setup(self):
self.number_line = NumberLine()
self.add(self.number_line)
LinearTransformationScene.setup(self)
class Introduce2Dto1DLinearTransformations(TwoDToOneDScene):
def construct(self):
number_line_words = TextMobject("Number line")
number_line_words.next_to(self.number_line, UP, buff = MED_BUFF)
numbers = VMobject(*self.number_line.get_number_mobjects())
self.remove(self.number_line)
self.apply_transposed_matrix(self.t_matrix)
self.play(
ShowCreation(number_line),
*[Animation(v) for v in self.i_hat, self.j_hat]
)
self.play(*map(Write, [numbers, number_line_words]))
self.dither()
class Symbolic2To1DTransform(Scene):
def construct(self):
func = TexMobject("L(", "\\vec{\\textbf{v}}", ")")
input_array = Matrix([2, 7])
input_array.highlight(YELLOW)
in_arrow = Arrow(LEFT, RIGHT, color = input_array.get_color())
func[1].highlight(input_array.get_color())
output_array = Matrix([1.8])
output_array.highlight(PINK)
out_arrow = Arrow(LEFT, RIGHT, color = output_array.get_color())
VMobject(
input_array, in_arrow, func, out_arrow, output_array
).arrange_submobjects(RIGHT, buff = SMALL_BUFF)
input_brace = Brace(input_array, DOWN)
input_words = input_brace.get_text("2d input")
output_brace = Brace(output_array, UP)
output_words = output_brace.get_text("1d output")
input_words.highlight(input_array.get_color())
output_words.highlight(output_array.get_color())
special_words = TextMobject("Linear", "functions are quite special")
special_words.highlight_by_tex("Linear", BLUE)
special_words.to_edge(UP)
self.add(func, input_array)
self.play(
GrowFromCenter(input_brace),
Write(input_words)
)
mover = input_array.copy()
self.play(
Transform(mover, Dot().move_to(func)),
ShowCreation(in_arrow),
rate_func = rush_into,
run_time = 0.5
)
self.play(
Transform(mover, output_array),
ShowCreation(out_arrow),
rate_func = rush_from,
run_time = 0.5
)
self.play(
GrowFromCenter(output_brace),
Write(output_words)
)
self.dither()
self.play(Write(special_words))
self.dither()
class FormalVsVisual(Scene):
def construct(self):
title = TextMobject("Linearity")
title.highlight(BLUE)
title.to_edge(UP)
line = Line(LEFT, RIGHT).scale(SPACE_WIDTH)
line.next_to(title, DOWN)
v_line = Line(line.get_center(), SPACE_HEIGHT*DOWN)
formal = TextMobject("Formal definition")
visual = TextMobject("Visual intuition")
formal.next_to(line, DOWN).shift(SPACE_WIDTH*LEFT/2)
visual.next_to(line, DOWN).shift(SPACE_WIDTH*RIGHT/2)
v_tex, w_tex = ["\\vec{\\textbf{%s}}"%c for c in "v", "w"]
additivity = TexMobject(
"L(", v_tex, "+", w_tex, ") = ",
"L(", v_tex, ")+", "L(", w_tex, ")"
)
additivity.highlight_by_tex(v_tex, V_COLOR)
additivity.highlight_by_tex(w_tex, W_COLOR)
scaling = TexMobject(
"L(", "c", v_tex, ")=", "c", "L(", v_tex, ")"
)
scaling.highlight_by_tex(v_tex, V_COLOR)
scaling.highlight_by_tex("c", GREEN)
visual_statement = TextMobject("""
Line of dots evenly spaced
dots remains evenly spaced
""")
visual_statement.submobject_gradient_highlight(YELLOW, MAROON_B)
properties = VMobject(additivity, scaling)
properties.arrange_submobjects(DOWN, buff = MED_BUFF)
for text, mob in (formal, properties), (visual, visual_statement):
mob.scale(0.75)
mob.next_to(text, DOWN, buff = MED_BUFF)
self.add(title)
self.play(*map(ShowCreation, [line, v_line]))
for mob in formal, visual, additivity, scaling, visual_statement:
self.play(Write(mob, run_time = 2))
self.dither()
class AdditivityProperty(TwoDToOneDScene):
CONFIG = {
"show_basis_vectors" : False,
"sum_before" : True
}
def construct(self):
v = Vector([2, 1], color = V_COLOR)
w = Vector([-1, 1], color = W_COLOR)
self.play(ShowCreation(v))
self.play(ShowCreation(w))
if self.sum_before:
sum_vect = self.play_sum(v, w)
else:
self.add_vector(v, animate = False)
self.add_vector(w, animate = False)
self.apply_transposed_matrix(self.t_matrix)
if not self.sum_before:
sum_vect = self.play_sum(v, w)
self.dither()
self.write_symbols(sum_vect)
def play_sum(self, v, w):
sum_vect = Vector(v.get_end()+w.get_end(), color = SUM_COLOR)
self.play(w.shift, v.get_end(), path_arc = np.pi/4)
self.play(ShowCreation(sum_vect))
for vect in v, w:
vect.target = vect.copy()
vect.target.set_fill(opacity = 0)
vect.target.set_stroke(width = 0)
sum_vect.target = sum_vect
self.play(*[
Transform(mob, mob.target)
for mob in v, w, sum_vect
])
self.add_vector(sum_vect, animate = False)
return sum_vect
def write_symbols(self, sum_vect):
v_tex, w_tex = ["\\vec{\\textbf{%s}}"%c for c in "v", "w"]
if self.sum_before:
tex_mob = TexMobject(
"L(", v_tex, "+", w_tex, ")"
)
tex_mob.next_to(sum_vect, UP)
else:
tex_mob = TexMobject(
"L(", v_tex, ")+L(", w_tex, ")"
)
tex_mob.next_to(sum_vect, DOWN)
tex_mob.highlight_by_tex(v_tex, V_COLOR)
tex_mob.highlight_by_tex(w_tex, W_COLOR)
self.play(Write(tex_mob))
self.dither()
class AdditivityPropertyPart2(AdditivityProperty):
CONFIG = {
"sum_before" : False
}
class ScalingProperty(TwoDToOneDScene):
CONFIG = {
"show_basis_vectors" : False,
"scale_before" : True,
"scalar" : 2,
}
def construct(self):
v = Vector([-1, 1], color = V_COLOR)
self.play(ShowCreation(v))
if self.scale_before:
scaled_vect = self.show_scaling(v)
self.add_vector(v, animate = False)
self.apply_transposed_matrix(self.t_matrix)
if not self.scale_before:
scaled_vect = self.show_scaling(v)
self.dither()
self.write_symbols(scaled_vect)
def show_scaling(self, v):
self.add_vector(v.copy().fade(), animate = False)
self.play(v.scale, self.scalar)
return v
def write_symbols(self, scaled_vect):
v_tex = "\\vec{\\textbf{v}}"
if self.scale_before:
tex_mob = TexMobject(
"L(", "c", v_tex, ")"
)
tex_mob.next_to(scaled_vect, UP)
else:
tex_mob = TexMobject(
"c", "L(", v_tex, ")",
)
tex_mob.next_to(scaled_vect, DOWN)
tex_mob.highlight_by_tex(v_tex, V_COLOR)
tex_mob.highlight_by_tex("c", GREEN)
self.play(Write(tex_mob))
self.dither()
class ScalingPropertyPart2(ScalingProperty):
CONFIG = {
"scale_before" : False
}
class ThisTwoDTo1DTransformWithDots(TwoDTo1DTransformWithDots):
pass
class AlwaysfollowIHatJHat(TeacherStudentsScene):
def construct(self):
i_tex, j_tex = ["$\\hat{\\%smath}$"%c for c in "i", "j"]
words = TextMobject(
"Always follow", i_tex, "and", j_tex
)
words.highlight_by_tex(i_tex, X_COLOR)
words.highlight_by_tex(j_tex, Y_COLOR)
self.teacher_says(words)
students = VMobject(*self.get_students())
ponderers = VMobject(*[
pi.copy().change_mode("pondering")
for pi in students
])
self.play(Transform(
students, ponderers,
submobject_mode = "lagged_start",
run_time = 2
))
self.random_blink(2)
class ShowMatrix(TwoDToOneDScene):
def construct(self):
self.apply_transposed_matrix(self.t_matrix)
self.play(Write(self.number_line.get_numbers()))
self.show_matrix()
def show_matrix(self):
for vect, char in zip([self.i_hat, self.j_hat], ["i", "j"]):
vect.words = TextMobject(
"$\\hat\\%smath$ lands on"%char,
str(int(vect.get_end()[0]))
)
direction = UP if vect is self.i_hat else DOWN
vect.words.next_to(vect.get_end(), direction, buff = LARGE_BUFF)
vect.words.highlight(vect.get_color())
matrix = Matrix([[1, 2]])
matrix_words = TextMobject("Transformation matrix: ")
matrix_group = VMobject(matrix_words, matrix)
matrix_group.arrange_submobjects()
matrix_group.to_edge(UP)
entries = matrix.get_entries()
self.play(
Write(matrix_words),
Write(matrix.get_brackets()),
run_time = 1
)
for i, vect in enumerate([self.i_hat, self.j_hat]):
self.play(
Write(vect.words, run_time = 1),
ApplyMethod(vect.shift, 0.5*UP, rate_func = there_and_back)
)
self.dither()
self.play(vect.words[1].copy().move_to, entries[i])
self.dither()
class FollowVectorViaCoordinates(TwoDToOneDScene):
CONFIG = {
"t_matrix" : [[1, 0], [-2, 0]],
"v_coords" : [3, 3],
"written_v_coords" : ["x", "y"],
"concrete" : False,
}
def construct(self):
v = Vector(self.v_coords)
array = Matrix(self.v_coords if self.concrete else self.written_v_coords)
array.get_entries().gradient_highlight(X_COLOR, Y_COLOR)
array.add_to_back(BackgroundRectangle(array))
v_label = TexMobject("\\vec{\\textbf{v}}", "=")
v_label[0].highlight(YELLOW)
v_label.next_to(v.get_end(), RIGHT)
v_label.add_background_rectangle()
array.next_to(v_label, RIGHT)
bases = self.i_hat, self.j_hat
basis_labels = self.get_basis_vector_labels(direction = "right")
scaling_anim_tuples = self.get_scaling_anim_tuples(
basis_labels, array, [DOWN, RIGHT]
)
self.play(*map(Write, basis_labels))
self.play(
ShowCreation(v),
Write(array),
Write(v_label)
)
self.add_foreground_mobject(v_label, array)
self.add_vector(v, animate = False)
self.dither()
to_fade = basis_labels
for i, anim_tuple in enumerate(scaling_anim_tuples):
self.play(*anim_tuple)
movers = self.get_mobjects_from_last_animation()
to_fade += movers[:-1]
if i == 1:
self.play(*[
ApplyMethod(m.shift, self.v_coords[0]*RIGHT)
for m in movers
])
self.dither()
self.play(
*map(FadeOut, to_fade) + [
vect.restore
for vect in self.i_hat, self.j_hat
]
)
self.apply_transposed_matrix(self.t_matrix)
self.play(Write(self.number_line.get_numbers(), run_time = 1))
self.play(
self.i_hat.shift, 0.5*UP,
self.j_hat.shift, DOWN,
)
if self.concrete:
new_labels = [
TexMobject("(%d)"%num)
for num in self.t_matrix[:,0]
]
else:
new_labels = [
TexMobject("L(\\hat{\\%smath})"%char)
for char in "i", "j"
]
new_labels[0].highlight(X_COLOR)
new_labels[1].highlight(Y_COLOR)
new_labels.append(
TexMobject("L(\\vec{\\textbf{v}})").highlight(YELLOW)
)
for label, vect, direction in zip(new_labels, list(bases) + [v], [UP, DOWN, UP]):
label.next_to(vect, direction)
self.play(*map(Write, new_labels))
self.dither()
scaling_anim_tuples = self.get_scaling_anim_tuples(
new_labels, array, [UP, DOWN]
)
for i, anim_tuple in enumerate(scaling_anim_tuples):
self.play(*anim_tuple)
movers = VMobject(*self.get_mobjects_from_last_animation())
self.dither()
self.play(movers.shift, self.i_hat.get_end()[0]*RIGHT)
self.dither()
if self.concrete:
final_label = TexMobject(str(int(v.get_end()[0])))
final_label.move_to(new_labels[-1])
final_label.highlight(new_labels[-1].get_color())
self.play(Transform(new_labels[-1], final_label))
self.dither()
def get_scaling_anim_tuples(self, labels, array, directions):
scaling_anim_tuples = []
bases = self.i_hat, self.j_hat
quints = zip(
bases, self.v_coords, labels,
array.get_entries(), directions
)
for basis, scalar, label, entry, direction in quints:
basis.save_state()
basis.scaled = basis.copy().scale(scalar)
basis.scaled.shift(basis.get_start() - basis.scaled.get_start())
scaled_label = VMobject(entry.copy(), label.copy())
entry.target, label.target = scaled_label.split()
entry.target.next_to(label.target, LEFT)
scaled_label.next_to(
basis.scaled,
direction
)
scaling_anim_tuples.append((
ApplyMethod(label.move_to, label.target),
ApplyMethod(entry.copy().move_to, entry.target),
Transform(basis, basis.scaled),
))
return scaling_anim_tuples
class FollowVectorViaCoordinatesConcrete(FollowVectorViaCoordinates):
CONFIG = {
"v_coords" : [4, 3],
"concrete" : True
}
class TwoDOneDMatrixMultiplication(Scene):
def construct(self):
matrix = Matrix([[1, -2]])
matrix.label = "Transform"
vector = Matrix([4, 3])
vector.label = "Vector"
matrix.next_to(vector, LEFT, buff = 0.2)
for m, vect in zip([matrix, vector], [UP, DOWN]):
x, y = m.get_entries()
x.highlight(X_COLOR)
y.highlight(Y_COLOR)
m.brace = Brace(m, vect)
m.label = m.brace.get_text(m.label)
matrix.label.highlight(BLUE)
vector.label.highlight(YELLOW)
starter_pairs = zip(vector.get_entries(), matrix.get_entries())
pairs = [
VMobject(
e1.copy(), TexMobject("\\cdot"), e2.copy()
).arrange_submobjects()
for e1, e2 in starter_pairs
]
symbols = map(TexMobject, ["=", "+"])
equation = VMobject(*it.chain(*zip(symbols, pairs)))
equation.arrange_submobjects()
equation.next_to(vector, RIGHT)
for m in vector, matrix:
self.play(Write(m))
self.play(
GrowFromCenter(m.brace),
Write(m.label),
run_time = 1
)
self.dither()
self.play(Write(VMobject(*symbols)))
for starter_pair, pair in zip(starter_pairs, pairs):
self.play(Transform(
VMobject(*starter_pair).copy(),
pair,
path_arc = -np.pi/2
))
self.dither()
class AssociationBetweenMatricesAndVectors(Scene):
def construct(self):
matrices_words = TextMobject("$1\\times 2$ matrices")
matrices_words.highlight(BLUE)
vectors_words = TextMobject("2d vectors")
vectors_words.highlight(YELLOW)
arrow = DoubleArrow(LEFT, RIGHT, color = WHITE)
VMobject(
matrices_words, arrow, vectors_words
).arrange_submobjects(buff = MED_BUFF)
matrices = VMobject(Matrix([[2, 7]]), Matrix([[1, -2]]))
vectors = VMobject(Matrix([2, 7]), Matrix([1, -2]))
for m in list(matrices) + list(vectors):
x, y = m.get_entries()
x.highlight(X_COLOR)
y.highlight(Y_COLOR)
matrices[0].next_to(matrices_words, UP, buff = MED_BUFF)
matrices[1].next_to(matrices_words, DOWN, buff = MED_BUFF)
vectors[0].next_to(vectors_words, UP, buff = MED_BUFF)
vectors[1].next_to(vectors_words, DOWN, buff = MED_BUFF)
self.play(*map(Write, [matrices_words, vectors_words]))
self.play(ShowCreation(arrow))
self.dither()
self.play(FadeIn(vectors))
vectors.save_state()
self.dither()
self.play(Transform(
vectors, matrices,
path_arc = np.pi/2,
submobject_mode = "lagged_start",
run_time = 2,
))
self.dither()
self.play(
vectors.restore,
path_arc = -np.pi/2,
submobject_mode = "lagged_start",
run_time = 2
)
self.dither()
class WhatAboutTheGeometricView(TeacherStudentsScene):
def construct(self):
self.student_says("""
What does this association
mean geometrically?
""",
pi_creature_target_mode = "raise_right_hand"
)
self.change_student_modes("pondering", "raise_right_hand", "pondering")
self.random_blink(2)
class AnExampleWillClarify(TeacherStudentsScene):
def construct(self):
self.teacher_says("An example will clarify...")
self.change_student_modes(*["happy"]*3)
self.random_blink(3)
class ImagineYouDontKnowThis(Scene):
def construct(self):
words = TextMobject("Imagine you don't know this")
words.highlight(RED)
words.scale(1.5)
self.play(Write(words))
self.dither()
class ProjectOntoUnitVectorNumberline(VectorScene):
def construct(self):
self.lock_in_faded_grid()
u_hat = Vector([1, 0], color = PINK)
u_hat.rotate(np.pil/6)
number_line = NumberLine()
numbers = number_line.get_numbers()
VMobject(number_line, numbers).rotate(u_hat.get_angle())

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@ -304,8 +304,9 @@ class Mobject(object):
"""
raise Exception("Not implemented")
def gradient_highlight(self, start_color, end_color):
raise Exception("Not implemented")
def gradient_highlight(self, *colors):
self.submobject_gradient_highlight(*colors)
return self
def submobject_gradient_highlight(self, *colors):
if len(colors) == 0:

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@ -347,7 +347,9 @@ class VMobject(Mobject):
self.set_points(points)
return self
class Group(VMobject):
#Alternate name to improve readability during use
pass
class VectorizedPoint(VMobject):
CONFIG = {

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@ -83,6 +83,10 @@ class NumberLine(VMobject):
result.append(mob)
return result
def get_numbers(self, *numbers, **kwargs):
##TODO, this shouldn't exist alongside the above method.
return VMobject(*self.get_number_mobjects(*numbers, **kwargs))
def add_numbers(self, *numbers, **kwargs):
self.numbers = self.get_number_mobjects(
*numbers, **kwargs