Animating Variables

Manim Variable - MVariable

In this section, you’ll find all the methods available to manipulate a MVariable (short for Manim Variable 😄). It can be useful to visualize variables in algorithms, their assignments, updates, and other operations. Like all MObject structures, you can animate these methods using the .animate method, allowing you to animate each operation provided by Manim DSA. Otherwise, methods will run without any animations.

You can also access the value of a MVariable directly and customize its appearance with labels and styling options.

Creating a MVariable

To represent a variable, initialize an object of type MVariable. As the first parameter, provide the initial value for the variable. The value can be of any type and will be automatically converted to its string representation for display. Optionally, you can customize the theme of the MVariable (see Customizing a MVariable).

Here’s an example that creates a MVariable and adds a label to it. Refer to Adding a label to a data structure if you miss the section on how to add labels to data structures!

Example: Creation

from manim import *

from manim_dsa import *

class Creation(Scene):
    def construct(self):
        mVariable = MVariable(5).add_label(
            Text("myVar", font="Cascadia Code", font_size=36),
            LEFT
        )
        self.play(Create(mVariable))
        self.wait()

Customizing a MVariable

ManimDSA provides various options for customizing the colors and styles of a MVariable. You can use these options by passing a predefined style configuration from the MVariableStyle class using the style parameter. Refer to MVariableStyle for more details. Alternatively, you can define a custom style to suit your needs.

In the following example, we use the BLUE style for the MVariable.

Example: CustomCreation

from manim import *

from manim_dsa import *

class CustomCreation(Scene):
    def construct(self):
        mVariable = MVariable(5, style=MVariableStyle.BLUE).add_label(
            Text("myVar", font="Cascadia Code", font_size=36),
            LEFT
        )
        self.play(Create(mVariable))
        self.wait()

Updating the value of a MVariable

The set_value() method allows you to change the value of a MVariable. The new value can be of any type and will be automatically converted to its string representation for display. This is particularly useful for demonstrating variable assignments and updates in algorithms.

In the example below, we create a MVariable with an initial value and then use the set_value() method to update it to a new value.

Example: SetValue

from manim import *

from manim_dsa import *

class SetValue(Scene):
    def construct(self):
        mVariable = MVariable(5, style=MVariableStyle.BLUE).add_label(
            Text("myVar", font="Cascadia Code", font_size=36),
            LEFT
        )
        self.play(Create(mVariable))
        self.wait()
        self.play(mVariable.animate.set_value(10))
        self.wait()