Python TexMobject.get_part_by_tex方法代码示例

# 需要导入模块: from mobject.tex_mobject import TexMobject [as 别名]
# 或者: from mobject.tex_mobject.TexMobject import get_part_by_tex [as 别名]
    def show_proportionality_to_dx_squared(self):
        ddf = self.ddf.copy()
        ddf.generate_target()
        ddf.target.next_to(self.ddf, UP, LARGE_BUFF)
        rhs = TexMobject(
            "\\approx", "(\\text{Some constant})", "(dx)^2"
        )
        rhs.scale(0.8)
        rhs.next_to(ddf.target, RIGHT)

        example_dx = TexMobject(
            "dx = 0.01 \\Rightarrow (dx)^2 = 0.0001"
        )
        example_dx.scale(0.8)
        example_dx.to_corner(UP+RIGHT)

        self.play(MoveToTarget(ddf))
        self.play(Write(rhs))
        self.dither()
        self.play(Write(example_dx))
        self.dither(2)
        self.play(FadeOut(example_dx))

        self.ddf = ddf
        self.dx_squared = rhs.get_part_by_tex("dx")

# 需要导入模块: from mobject.tex_mobject import TexMobject [as 别名]
# 或者: from mobject.tex_mobject.TexMobject import get_part_by_tex [as 别名]
    def write_second_derivative(self):
        ddf_over_dx_squared = TexMobject(
            "{d(df)", "\\over", "(dx)^2}"
        )
        ddf_over_dx_squared.scale(0.8)
        ddf_over_dx_squared.move_to(self.ddf, RIGHT)
        ddf_over_dx_squared.highlight_by_tex("df", self.ddf.get_color())
        parens = VGroup(
            ddf_over_dx_squared[0][1],
            ddf_over_dx_squared[0][4],
            ddf_over_dx_squared[2][0],
            ddf_over_dx_squared[2][3],
        )

        right_shifter = ddf_over_dx_squared[0][0]
        left_shifter = ddf_over_dx_squared[2][4]

        exp_two = TexMobject("2")
        exp_two.highlight(self.ddf.get_color())
        exp_two.scale(0.5)
        exp_two.move_to(right_shifter.get_corner(UP+RIGHT), LEFT)
        exp_two.shift(MED_SMALL_BUFF*RIGHT)
        pre_exp_two = VGroup(ddf_over_dx_squared[0][2])

        self.play(
            Write(ddf_over_dx_squared.get_part_by_tex("over")),
            *[
                ReplacementTransform(
                    mob, 
                    ddf_over_dx_squared.get_part_by_tex(tex),
                    path_arc = -np.pi/2,                    
                )
                for mob, tex in (self.ddf, "df"), (self.dx_squared, "dx")
            ]
        )
        self.dither(2)
        self.play(FadeOut(parens))
        self.play(
            left_shifter.shift, 0.2*LEFT,
            right_shifter.shift, 0.2*RIGHT,
            ReplacementTransform(pre_exp_two, exp_two),
            ddf_over_dx_squared.get_part_by_tex("over").scale_in_place, 0.8
        )
        self.dither(2)

# 需要导入模块: from mobject.tex_mobject import TexMobject [as 别名]
# 或者: from mobject.tex_mobject.TexMobject import get_part_by_tex [as 别名]
    def get_expression(self, base):
        expression = TexMobject(
            "{d(", "%d^"%base, "t", ")", "\\over \\,", "dt}",
            "=", "%d^"%base, "t", "(%.4f\\dots)"%np.log(base),
        )
        expression.highlight_by_tex("t", YELLOW)
        expression.highlight_by_tex("dt", GREEN)
        expression.highlight_by_tex("\\dots", BLUE)

        brace = Brace(expression.get_part_by_tex("\\dots"), UP)
        brace_text = brace.get_text("$\\ln(%d)$"%base)
        for mob in brace, brace_text:
            mob.set_fill(opacity = 0)

        expression.add(brace, brace_text)
        return expression

# 需要导入模块: from mobject.tex_mobject import TexMobject [as 别名]
# 或者: from mobject.tex_mobject.TexMobject import get_part_by_tex [as 别名]
    def construct(self):
        clunky_deriv = TexMobject(
            "{d", "\\big(", "{df", "\\over", "dx}", "\\big)",
            "\\over", "dx }"
        )
        over_index = clunky_deriv.index_of_part(
            clunky_deriv.get_parts_by_tex("\\over")[1]
        )
        numerator = VGroup(*clunky_deriv[:over_index])
        denominator = VGroup(*clunky_deriv[over_index+1:])


        rp = clunky_deriv.get_part_by_tex("(")
        lp = clunky_deriv.get_part_by_tex(")")
        dfs, overs, dxs = map(clunky_deriv.get_parts_by_tex, [
            "df", "over", "dx"
        ])
        df_over_dx = VGroup(dfs[0], overs[0], dxs[0])
        d = clunky_deriv.get_part_by_tex("d")
        d_over_dx = VGroup(d, overs[1], dxs[1])

        d2f_over_dx2 = TexMobject("{d^2 f", "\\over", "dx", "^2}")
        d2f_over_dx2.highlight_by_tex("dx", YELLOW)

        for mob in clunky_deriv, d2f_over_dx2:
            mob.next_to(self.teacher, UP+LEFT)

        for mob in numerator, denominator:
            circle = Circle(color = YELLOW)
            circle.replace(mob, stretch = True)
            circle.scale_in_place(1.3)
            mob.circle = circle
        dx_to_zero = TexMobject("dx \\to 0")
        dx_to_zero.highlight(YELLOW)
        dx_to_zero.next_to(clunky_deriv, UP+LEFT)

        self.student_says(
            "What's that notation?",
            target_mode = "raise_left_hand"
        )
        self.change_student_modes("confused", "raise_left_hand", "confused")
        self.play(
            FadeIn(
                clunky_deriv,
                run_time = 2,
                submobject_mode = "lagged_start"
            ),
            RemovePiCreatureBubble(self.get_students()[1]),
            self.teacher.change_mode, "raise_right_hand"
        )
        self.dither()
        self.play(ShowCreation(numerator.circle))
        self.dither()
        self.play(ReplacementTransform(
            numerator.circle,
            denominator.circle,
        ))
        self.dither()
        self.play(
            FadeOut(denominator.circle),
            Write(dx_to_zero),
            dxs.highlight, YELLOW
        )
        self.dither()
        self.play(
            FadeOut(dx_to_zero),
            *[ApplyMethod(pi.change, "plain") for pi in self.get_pi_creatures()]
        )
        self.play(
            df_over_dx.scale, dxs[1].get_height()/dxs[0].get_height(),
            df_over_dx.move_to, d_over_dx, RIGHT,
            FadeOut(VGroup(lp, rp)),
            d_over_dx.shift, 0.8*LEFT + 0.05*UP,
        )
        self.dither()
        self.play(*[
            ReplacementTransform(
                group,
                VGroup(d2f_over_dx2.get_part_by_tex(tex))
            )
            for group, tex in [
                (VGroup(d, dfs[0]), "d^2"),
                (overs, "over"),
                (dxs, "dx"),
                (VGroup(dxs[1].copy()), "^2}"),
            ]
        ])
        self.dither(2)
        self.student_says(
            "How does one... \\\\ read that?",
            student_index = 0,
        )
        self.play(self.teacher.change, "happy")
        self.dither(2)