Animating Arrays

Manim Array - MArray

In this section, you’ll find all the methods available to manipulate a MArray (short for Manim Array 😄). Key actions include adding and removing elements, swapping elements, and other essential 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 each element in a MArray using the [] operator and specifying the element’s index.

Creating a MArray

To represent an array, initialize an object of type MArray. As the first parameter, provide a list of values to insert into the MArray. Optionally, you can specify the direction and customize the theme of the MArray (see Customizing a MArray).

Here’s an example that creates a MArray with a list of five numbers. By default, the array direction is to the right.

Example: Creation

from manim import *

from manim_dsa import *

class Creation(Scene):
    def construct(self):
        mArray = MArray([1, 2, 3, 4, 5])
        self.play(Create(mArray))
        self.wait()

Customizing a MArray

ManimDSA provides various options for customizing the colors and styles of a MArray. You can use these options by passing a predefined style configuration from the MArrayStyle class using the style parameter. Refer to MArrayStyle 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 MArray.

Example: CustomCreation

from manim import *

from manim_dsa import *

class CustomCreation(Scene):
    def construct(self):
        mArray = MArray(
            [1, 2, 3, 4, 5],
            style=MArrayStyle.BLUE
        )
        self.play(Create(mArray))
        self.wait()

Adding indexes to a MArray

The add_indexes() method allows you to add indexes to a MArray. You can specify the position and spacing of the indexes relative to the MArray, as well as customize the properties of the indexes themselves.

In the following example, after creating a MArray, we use the add_indexes() method to add indexes above each element. Additionally, we customize the color of the indexes, choosing the purple configuration provided by ManimDSA.

Example: AddIndexes

from manim import *

from manim_dsa import *

class AddIndexes(Scene):
    def construct(self):
        mArray = (
            MArray(
                [1, 2, 3, 4, 5],
                style=MArrayStyle.PURPLE
            )
            .add_indexes()
        )
        self.play(Create(mArray))
        self.wait()

Updating the value of an element in a MArray

The set_value() method allows you to change the value of an element in a MArray. As stated earlier, it is sufficient to use the [] operator to access the element and then call the set_value() method on it.

In the example below, we create a MArray with five elements and then use the set_value() method to update the third element to a new value.

Example: SetValue

from manim import *

from manim_dsa import *

class SetValue(Scene):
    def construct(self):
        mArray = (
            MArray(
                [1, 2, 3, 4, 5],
                style=MArrayStyle.BLUE
            )
            .add_indexes()
        )
        self.play(Create(mArray))
        self.play(mArray[2].animate.set_value(10))
        self.wait()

Appending an element to a MArray

The append() method allows you to add an element to the end of a MArray. The new element automatically inherits the properties specified in the configuration dictionaries. Furthermore, if indexes have been added to the MArray, the new element will also include a corresponding index.

In the example below, we create a MArray with indexes and then use the append() method to add a new element.

Example: Append

from manim import *

from manim_dsa import *

class Append(Scene):
    def construct(self):
        mArray = (
            MArray(
                [1, 2, 3, 4, 5],
                style=MArrayStyle.BLUE,
            )
            .add_indexes()
        )
        self.play(Create(mArray))
        self.play(mArray.animate.append(6))
        self.wait()

Removing an element from a MArray

The pop() method allows you to remove an element from a MArray by specifying the position of the element to be removed. After the removal, the elements that follow the removed one shift left by one position, and their corresponding indexes (if present) are decremented by one.

In the example below, we create a MArray with indexes and use the pop() method to remove the third element.

Example: Pop

from manim import *

from manim_dsa import *

class Pop(Scene):
    def construct(self):
        mArray = (
            MArray(
                [1, 2, 3, 4, 5],
                style=MArrayStyle.BLUE
            )
            .add_indexes()
        )
        self.play(Create(mArray))
        self.play(mArray.animate.pop(2))
        self.wait()

Swapping elements in a MArray

The swap() method allows you to swap two elements in a MArray by specifying their indices. This can be useful for visualizing algorithms that involve element rearrangement.

In the example below, we create a MArray with five elements and then use the swap() method to swap the second and fourth elements.

Example: Swap

from manim import *

from manim_dsa import *

class Swap(Scene):
    def construct(self):
        mArray = (
            MArray(
                [1, 2, 3, 4, 5],
                style=MArrayStyle.BLUE
            )
            .add_indexes()
        )
        self.play(Create(mArray))
        self.play(mArray.animate.swap(1, 3))
        self.wait()