Lists#

The same rules apply for lists as for variables regarding for all sprites and for this sprite only.

Declaration#

list list_name;

list type_name list_name;

Operations#

Add item to list#

add value to list_name;

Delete item from list at index#

delete list_name[index];

Delete all items from list#

delete list_name;

Insert item at index in list#

insert value at list_name[index];

Replace item at index in list#

list_name[index] = value;

Get item at index in list#

value = list_name[index];

Get index of item in list#

TODO

Get length of list#

len = length list_name;

Check if item is in list#

if value in list_name {
    ...
}

Show/Hide List Monitor#

show list_name;

hide list_name;

Get random/last item in list#

value = list_name["random"];

value = list_name["last"];

Compound Assignment#

Operator	Implementation
`list_name[index]++;`
`list_name[index]--;`
`list_name[index] += y;`
`list_name[index] -= y;`
`list_name[index] *= y;`
`list_name[index] /= y;`
`list_name[index] //= y;`
`list_name[index] %= y;`
`list_name[index] &= y;`

List Data#

Initial data for lists can be stored inside the project. This behaves the same way loading text files into lists works in the Scratch editor. In addition to loading text files, you can also load data from various scripts and commands. This is useful for creating look-up tables or loading data from images or videos.

Loading data from text files#

Each line in the text file will be added to the list as a separate item.

list list_name = file ```path/to/file.txt```;

Loading data from bash script#

The bash script enclosed in triple-backticks will be executed, and the standard output will be stored in the list, one item per line. The working directory will be set to the project directory.

list list_name = ```cat path/to/file.txt```;

Loading data from any other program#

The name of the program may be specified before the triple-backticks. This program will be executed with the standard input set to the script enclosed in the triple-backticks. The standard output will be stored in the list, one item per line. The working directory will be set to the project directory.

Any program that accepts input from stdin and outputs to stdout can be used.

For example, to load data from a python script:

list list_name = python ```
import random
for _ in range(5):
    print(random.randint(-5, 5))
```;

Tip

If your script takes a long time to run, you can use bash to cache the output of the script.

Let's say that your script converts a file DEPENDENCY.txt. You wish to only re-run the script if the file DEPENDENCY.txt has changed. We can use stat to get the last modification time of the file.

TIME=$(stat -c %Y DEPENDENCY.txt)
if [ $TIME -eq $(< DEPENDENCY.time)]; then
    cat DEPENDENCY.cached
    exit
fi
echo $TIME > DEPENDENCY.time
python convert_file.py DEPENDENCY.txt | tee DEPENDENCY.cached

Struct List Data#

If the list's type is a struct, each field will be filled with the value of the corresponding line in the data.

Example:

struct vec3d { x, y, z };
list vec3d points = file ```file.txt```;

contents of file.txt:

resulting in the following list:

[
    vec3d {
        x: 10,
        y: 20,
        z: 30
    },
    vec3d {
        x: 40,
        y: 50,
        z: 60
    }
]