Variable

限定名称：manim.mobject.text.numbers.Variable

类 Variable(var, label, var_type=<class 'manim.mobject.text.numbers.DecimalNumber'>, num_decimal_places=2, **kwargs)[源代码]

继承：VMobject

一个用于显示文本的类，文本格式为“label = value”，其中值会从ValueTracker中持续更新。

参数:

  • var (float) – 您需要跟踪和显示的初始值。

  • label (str | Tex | MathTex | Text | SingleStringMathTex) – 变量的标签。原始字符串会转换为MathTex对象。

  • var_type (DecimalNumber | Integer) – 用于显示数字的类。默认为DecimalNumber。

  • num_decimal_places (int) – 变量中要显示的十进制位数。默认为2。如果var_type是Integer，则此参数将被忽略。

  • kwargs – 其他将传递给~.Mobject的参数。

label

变量的标签，例如x = ...。

类型:

联合类型[str, Tex, MathTex, Text, SingleStringMathTex]

tracker

用于更新屏幕上变量的值。

类型:

ValueTracker

value

变量值的Tex表示。

类型:

联合类型[DecimalNumber, Integer]

示例

常规用法

# DecimalNumber type
var = 0.5
on_screen_var = Variable(var, Text("var"), num_decimal_places=3)
# Integer type
int_var = 0
on_screen_int_var = Variable(int_var, Text("int_var"), var_type=Integer)
# Using math mode for the label
on_screen_int_var = Variable(int_var, "{a}_{i}", var_type=Integer)

示例：VariablesWithValueTracker 

from manim import *

class VariablesWithValueTracker(Scene):
    def construct(self):
        var = 0.5
        on_screen_var = Variable(var, Text("var"), num_decimal_places=3)

        # You can also change the colours for the label and value
        on_screen_var.label.set_color(RED)
        on_screen_var.value.set_color(GREEN)

        self.play(Write(on_screen_var))
        # The above line will just display the variable with
        # its initial value on the screen. If you also wish to
        # update it, you can do so by accessing the `tracker` attribute
        self.wait()
        var_tracker = on_screen_var.tracker
        var = 10.5
        self.play(var_tracker.animate.set_value(var))
        self.wait()

        int_var = 0
        on_screen_int_var = Variable(
            int_var, Text("int_var"), var_type=Integer
        ).next_to(on_screen_var, DOWN)
        on_screen_int_var.label.set_color(RED)
        on_screen_int_var.value.set_color(GREEN)

        self.play(Write(on_screen_int_var))
        self.wait()
        var_tracker = on_screen_int_var.tracker
        var = 10.5
        self.play(var_tracker.animate.set_value(var))
        self.wait()

        # If you wish to have a somewhat more complicated label for your
        # variable with subscripts, superscripts, etc. the default class
        # for the label is MathTex
        subscript_label_var = 10
        on_screen_subscript_var = Variable(subscript_label_var, "{a}_{i}").next_to(
            on_screen_int_var, DOWN
        )
        self.play(Write(on_screen_subscript_var))
        self.wait()

class VariablesWithValueTracker(Scene):
    def construct(self):
        var = 0.5
        on_screen_var = Variable(var, Text("var"), num_decimal_places=3)

        # You can also change the colours for the label and value
        on_screen_var.label.set_color(RED)
        on_screen_var.value.set_color(GREEN)

        self.play(Write(on_screen_var))
        # The above line will just display the variable with
        # its initial value on the screen. If you also wish to
        # update it, you can do so by accessing the `tracker` attribute
        self.wait()
        var_tracker = on_screen_var.tracker
        var = 10.5
        self.play(var_tracker.animate.set_value(var))
        self.wait()

        int_var = 0
        on_screen_int_var = Variable(
            int_var, Text("int_var"), var_type=Integer
        ).next_to(on_screen_var, DOWN)
        on_screen_int_var.label.set_color(RED)
        on_screen_int_var.value.set_color(GREEN)

        self.play(Write(on_screen_int_var))
        self.wait()
        var_tracker = on_screen_int_var.tracker
        var = 10.5
        self.play(var_tracker.animate.set_value(var))
        self.wait()

        # If you wish to have a somewhat more complicated label for your
        # variable with subscripts, superscripts, etc. the default class
        # for the label is MathTex
        subscript_label_var = 10
        on_screen_subscript_var = Variable(subscript_label_var, "{a}_{i}").next_to(
            on_screen_int_var, DOWN
        )
        self.play(Write(on_screen_subscript_var))
        self.wait()

示例：VariableExample 

from manim import *

class VariableExample(Scene):
    def construct(self):
        start = 2.0

        x_var = Variable(start, 'x', num_decimal_places=3)
        sqr_var = Variable(start**2, 'x^2', num_decimal_places=3)
        Group(x_var, sqr_var).arrange(DOWN)

        sqr_var.add_updater(lambda v: v.tracker.set_value(x_var.tracker.get_value()**2))

        self.add(x_var, sqr_var)
        self.play(x_var.tracker.animate.set_value(5), run_time=2, rate_func=linear)
        self.wait(0.1)

class VariableExample(Scene):
    def construct(self):
        start = 2.0

        x_var = Variable(start, 'x', num_decimal_places=3)
        sqr_var = Variable(start**2, 'x^2', num_decimal_places=3)
        Group(x_var, sqr_var).arrange(DOWN)

        sqr_var.add_updater(lambda v: v.tracker.set_value(x_var.tracker.get_value()**2))

        self.add(x_var, sqr_var)
        self.play(x_var.tracker.animate.set_value(5), run_time=2, rate_func=linear)
        self.wait(0.1)

方法

属性

animate (动画)

用于动画化 self 的任何方法的应用。

animation_overrides (动画覆盖)

颜色

depth (深度)

mobject 的深度。

fill_color (填充颜色)

如果存在多种颜色（用于渐变），则返回第一种颜色

height (高度)

mobject 的高度。

n_points_per_curve (每条曲线的点数)

sheen_factor (光泽因子)

stroke_color (描边颜色)

width (宽度)

mobject 的宽度。
_original__init__(var, label, var_type=<class 'manim.mobject.text.numbers.DecimalNumber'>, num_decimal_places=2, **kwargs)

初始化自身。有关准确签名，请参阅 help(type(self))。

参数: