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| 184_notes:lists [2022/05/06 21:59] – woodsna1 | 184_notes:lists [2022/05/07 01:20] (current) – woodsna1 |
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| ====== Coding: Lists ====== | ====== Coding: Lists ====== |
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| We often need a way to represent a group of objects or values in code. Python makes this easy with lists. A list gives a name to a collection of any Python objects. In Glowscript, we often use lists that include spheres, arrows, rings, and other shapes. Creating a list is easy: | We often need a way to represent a group of objects or values in code. Python makes this easy with lists. A list gives a name to a collection of any Python objects. You can think of a list like an excel spreadsheet, it has many rows (each representing an object), and each row has several columns (representing the attributes of the object). |
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| | In Glowscript, we often use lists that include spheres, arrows, rings, and other shapes. Creating a list is easy: |
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| <code> | <code> |
| </code> | </code> |
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| You can think of a list like an excel spreadsheet, it has many rows (each representing an object), and each row has several columns (representing the attributes of the object). You can also access each bucket in a list to update or retrieve the object within it. One way is by using list indexing. Indices in a Python list start at 0 for the first element: | You can also access each bucket in a list to update or retrieve the object within it. One way is by using list indexing. Indices in a Python list start at 0 for the first element: |
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| <code> | <code> |
| </code> | </code> |
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| To change the value in a bucket, simply use = to assign to it: | To change the value in a bucket, simply use "=" to assign to it: |
| <code> | <code> |
| list_of_numbers[0] = 250 # Change the first element | list_of_numbers[0] = 250 # Change the first element |
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| ===== Lists and For Loops ===== | ===== Lists and For Loops ===== |
| | ==== Lecture Video ==== |
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| | {{youtube>Rvpmo95XBNA?large}} |
| We often want to move through a list and read or change each value one-by-one. The easiest way to iterate through a list in Python is using a for loop. | We often want to move through a list and read or change each value one-by-one. The easiest way to iterate through a list in Python is using a for loop. |
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| index = 0 | index = 0 |
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| while index < len(list_of_numbers): | while index < len(list_of_numbers): # Conditional |
| list_of_numbers[index] += 1 | list_of_numbers[index] += 5 # Increase each number by 5 |
| index += 1 | index += 1 # Increment the counter variable |
| </code> | </code> |
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