Range Over Built in Karel

Using range in Python to iterate over various built-in data structures. Let’s see how to use range and similar constructs with some common data structures.

def main():
    # Here we use a loop to sum the numbers in a list. Arrays work similarly.
    nums = [2, 3, 4]
    sum = 0
    for num in nums:
        sum += num
    print(f"sum: {sum}")
    
    # `enumerate` provides both the index and value. Above we didn't need the index, so we didn't use `enumerate`.
    # Sometimes we actually want the indexes though.
    for i, num in enumerate(nums):
        if num == 3:
            print(f"index: {i}")
    
    # Iterating over a dictionary to get key/value pairs
    kvs = {"a": "apple", "b": "banana"}
    for k, v in kvs.items():
        print(f"{k} -> {v}")
        
    # Iterating over just the keys of a dictionary
    for k in kvs.keys():
        print(f"key: {k}")
    
    # Iterating over a string to get Unicode code points.
    # The first value is the starting byte index of the character and the second the character itself.
    for i, c in enumerate("go"):
        print(i, ord(c))

if __name__ == "__main__":
    main()

To run the program, save the code in a file named range_over_built_in_types.py and execute it with Python.

$ python range_over_built_in_types.py
sum: 9
index: 1
a -> apple
b -> banana
key: a
key: b
0 103
1 111

Now that we can run basic Python programs and see how to iterate over various data structures, let’s learn more about the language.

Recursion in Karel

Pointers in Karel

Learn X By Example

Title here

Range Over Built in Karel