It took us a little while in class today to remember how 2D arrays work, so I thought I might go over it.
A 2 dimentional (2D) array is an array of arrays. So [[1,2,3,4],[5,6,7,8],[9,10,11,12]] is a 3 item array where each item is a 4 item array. This can be written as
[[1,2,3,4],
[5,6,7,8],
[9,10,11,12]]
You might notice that it looks like a grid (or matrix), this is where the 2D comes in to the name. In python we can create the array and assign it.
![2d](https://glow-prod-nl.s3.eu-west-1.amazonaws.com/nl/public/ColtnessHS-ComputingScience/uploads/sites/12638/2016/11/2D-300x212.png?X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Security-Token=IQoJb3JpZ2luX2VjECYaCWV1LXdlc3QtMSJIMEYCIQCAjR9oZ0Ss8axoZ6dCVd8bvMgylpBkstdC9RA9sbCpcQIhANFnu2pA201YOBDEJ1b8d2%2BVP8e12YNWyYHr70q3laeEKsEFCO%2F%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FwEQBRoMMjczNTcwMTk1NDMzIgzMNxtdXfg0ViiIpCcqlQUPRwtG6TECxMUr5stlc3v4qe2glltX70TuWqKKqYOioFP%2FWmw0WTG6f%2BDQwxKvutRU%2FnX2n1AOx8%2B2bqTdhVax2QwZrq3bTOJWeQtsJfYm2ziOEoX79ETKm9maIUig1t1R9UubE983A2isVCRxorx96QYIwdSzsw0nZIz9hBFKmF3Pjno7PtR2vAoUIp4zK%2FFKZFO1H6yjGCgn%2BIMgz1v2z7Zb5%2BOM2q5y%2BD9FXWT59n14BSuK52bIlKu12NQcN4P%2B1gjy%2F0WNQ6xEKVveCx%2BZpCRJ6gwYVDOZ7Ga0x5D5vDrgvqx9fOYcdNR%2BaXOlDLndnoSR%2FVLtJXP4inICIzhvgm4AgF%2BvvnvJf4IF3cBVm9QJM6McWpEjlPaE54s27xy%2F%2BlDaafu6gvTalwR3zo%2Fr0%2BheoHSiiuHUu3rikQzAIXdwRwsQOPwV8st7EeVlV4gpXqjuXBlwIU5S7TJ1d7F5j0jTu2fJrEllwQIxykmlK4QhHFSHTHK%2FEYayk%2B47inZlBmwzlIk3lWkJnjfTQYIXZjoZ4NZ%2F6a2sYL8ivnnpn6e8TndRkg7i%2BFU6SqvmKWnH1hq0OMUFEe1sk0cmn8MoxCs2QTX%2BuVGBglzhiCYqHFsR587V0%2FcOxrs2j7xGbnyKOfMq%2B9FrjbZM32OM000jUB0HBz43gDolhCXataJWSWiKa%2B3QAmrQgNqTng%2FF0ol6i9KJKsr%2BIyR%2BEnAdALlPlYjetd5xYz7WPF8SeNUQ31VVn4UaJE6hzCm9r7biAwT77q8okYDjdeH%2F8G1AuVoeobgVoeFkprd%2FpUJ95r2ewEVjeNFUyXxzlpBsb4JEXUvn2taWgXaCzKrBk%2FkVLynXELKodlD5qqsE6w1pBFLiBeBxwy4RMIqM37QGOrABVVRkaSq3rX01NRjYMDJbovBJIL0iVeG%2BdwiHYc3QT%2FounqBhvMK%2B9I6lyAnBgcxAmNIHaZq3eiquWudh4RvhL7sAnjajuQbwNJpWgngwG5N7qqyyTGaJhgFoArx2Y2gxp%2F7qP9pVnmXV1hiPJNUIwuMkhbX%2FyraRms2BTw4AVHSiRNhAQfge7XQscOOXjMidFNK%2Fd3tfH5cQ4Mk8noJCvI1BCumeYmnDPkjO0CyQLcg%3D&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=ASIAT7MQN47UW5H7GZUU%2F20240717%2Feu-west-1%2Fs3%2Faws4_request&X-Amz-Date=20240717T133007Z&X-Amz-SignedHeaders=host&X-Amz-Expires=900&X-Amz-Signature=d3b227840654c540349d64eca8a5612f2bab91f4f0203f4a10a59a229d6d7ed5)
In the code above you can see the the individual elements of the 2D array are accessed using a pair of square brackets [][]. Using the image below we can see the [1][2] is number 7, as demonstrated in the program above.
We can use a loop to display each value in the 1st column.
![Using a for loop with a 2D array.](https://glow-prod-nl.s3.eu-west-1.amazonaws.com/nl/public/ColtnessHS-ComputingScience/uploads/sites/12638/2016/11/for2d-300x114.png?X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Security-Token=IQoJb3JpZ2luX2VjECYaCWV1LXdlc3QtMSJIMEYCIQCAjR9oZ0Ss8axoZ6dCVd8bvMgylpBkstdC9RA9sbCpcQIhANFnu2pA201YOBDEJ1b8d2%2BVP8e12YNWyYHr70q3laeEKsEFCO%2F%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FwEQBRoMMjczNTcwMTk1NDMzIgzMNxtdXfg0ViiIpCcqlQUPRwtG6TECxMUr5stlc3v4qe2glltX70TuWqKKqYOioFP%2FWmw0WTG6f%2BDQwxKvutRU%2FnX2n1AOx8%2B2bqTdhVax2QwZrq3bTOJWeQtsJfYm2ziOEoX79ETKm9maIUig1t1R9UubE983A2isVCRxorx96QYIwdSzsw0nZIz9hBFKmF3Pjno7PtR2vAoUIp4zK%2FFKZFO1H6yjGCgn%2BIMgz1v2z7Zb5%2BOM2q5y%2BD9FXWT59n14BSuK52bIlKu12NQcN4P%2B1gjy%2F0WNQ6xEKVveCx%2BZpCRJ6gwYVDOZ7Ga0x5D5vDrgvqx9fOYcdNR%2BaXOlDLndnoSR%2FVLtJXP4inICIzhvgm4AgF%2BvvnvJf4IF3cBVm9QJM6McWpEjlPaE54s27xy%2F%2BlDaafu6gvTalwR3zo%2Fr0%2BheoHSiiuHUu3rikQzAIXdwRwsQOPwV8st7EeVlV4gpXqjuXBlwIU5S7TJ1d7F5j0jTu2fJrEllwQIxykmlK4QhHFSHTHK%2FEYayk%2B47inZlBmwzlIk3lWkJnjfTQYIXZjoZ4NZ%2F6a2sYL8ivnnpn6e8TndRkg7i%2BFU6SqvmKWnH1hq0OMUFEe1sk0cmn8MoxCs2QTX%2BuVGBglzhiCYqHFsR587V0%2FcOxrs2j7xGbnyKOfMq%2B9FrjbZM32OM000jUB0HBz43gDolhCXataJWSWiKa%2B3QAmrQgNqTng%2FF0ol6i9KJKsr%2BIyR%2BEnAdALlPlYjetd5xYz7WPF8SeNUQ31VVn4UaJE6hzCm9r7biAwT77q8okYDjdeH%2F8G1AuVoeobgVoeFkprd%2FpUJ95r2ewEVjeNFUyXxzlpBsb4JEXUvn2taWgXaCzKrBk%2FkVLynXELKodlD5qqsE6w1pBFLiBeBxwy4RMIqM37QGOrABVVRkaSq3rX01NRjYMDJbovBJIL0iVeG%2BdwiHYc3QT%2FounqBhvMK%2B9I6lyAnBgcxAmNIHaZq3eiquWudh4RvhL7sAnjajuQbwNJpWgngwG5N7qqyyTGaJhgFoArx2Y2gxp%2F7qP9pVnmXV1hiPJNUIwuMkhbX%2FyraRms2BTw4AVHSiRNhAQfge7XQscOOXjMidFNK%2Fd3tfH5cQ4Mk8noJCvI1BCumeYmnDPkjO0CyQLcg%3D&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=ASIAT7MQN47UW5H7GZUU%2F20240717%2Feu-west-1%2Fs3%2Faws4_request&X-Amz-Date=20240717T133007Z&X-Amz-SignedHeaders=host&X-Amz-Expires=900&X-Amz-Signature=661bad5a72c9f11d322caadc53205d30f6730754488fd7895f0ef2544d68898c)
Or a nested for to display each item in each array