跳转至

变量

合格名称：manim.mobject.text.numbers.Variable

Python
1
class Variable(var, label, var_type=<class 'manim.mobject.text.numbers.DecimalNumber'>, num_decimal_places=2, **kwargs)

Bases: VMobject

一个用于显示文本的类，该文本显示“label = value”，并且值从ValueTracker.

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。原始字符串被转换为MathTex对象。
  • var_type ( DecimalNumber | Integer ) – 用于显示数字的类。默认为DecimalNumber.
  • num_decimal_places ( int ) – 要在变量中显示的小数位数。默认为 2。如果 var_type 为Integer，则忽略此参数。
  • kwargs – 要传递给~.Mobject 的其他参数。

label

变量的标签，例如。x = ...

类型

Union[ str, Tex, MathTex, Text, SingleStringMathTex]

tracker

对于更新屏幕上变量的值很有用。

类型

ValueTracker

value

变量值的 tex。

类型

Union[ DecimalNumber, Integer]

例子

正常使用：

Python
1
2
3
4
5
6
7
8
# 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

Python
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
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()

示例：变量示例

Python
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
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)

方法

属性
animate 用于对 的任何方法的应用程序进行动画处理self。
animation_overrides
color
depth 对象的深度。
fill_color 如果有多种颜色（对于渐变），则返回第一个颜色
height mobject 的高度。
n_points_per_curve
sheen_factor
stroke_color
width mobject 的宽度。