05_loops.py

# /// script
# requires-python = ">=3.10"
# dependencies = [
#     "marimo",
# ]
# ///

import marimo

__generated_with = "0.18.4"
app = marimo.App()


@app.cell(hide_code=True)
def _(mo):
    mo.md("""
    # Loops

    Let's learn how Python helps us repeat tasks efficiently with loops.

    A "loop" is a way to execute a block of code multiple times. Python has two
    main types of loops:

    ```python
    # For loop: when you know how many times to repeat
    for i in range(5):
        print(i)

    # While loop: when you don't know how many repetitions
    while condition:
        do_something()
    ```

    Let's start with a simple list to explore loops. Feel free to modify this list and see how the subsequent outputs change.
    """)
    return


@app.cell
def _():
    sample_fruits = ["apple", "banana", "orange", "grape"]
    return (sample_fruits,)


@app.cell(hide_code=True)
def _(mo):
    mo.md("""
    ## The for loop

    The for loop is perfect for iterating over sequences.
    Try changing the `sample_fruits` list above and see how the output changes.
    """)
    return


@app.cell
def _(sample_fruits):
    for _fruit in sample_fruits:
        print(f"I like {_fruit}s!")
    return


@app.cell(hide_code=True)
def _(mo):
    mo.md("""
    ### Getting the position of an item

    When you need both the item and its position, use `enumerate()`:
    """)
    return


@app.cell
def _(sample_fruits):
    for _idx, _fruit in enumerate(sample_fruits):
        print(f"{_idx + 1}. {_fruit}")
    return


@app.cell(hide_code=True)
def _(mo):
    mo.md("""
    ### Iterating over a range of numbers

    `range()` is a powerful function for generating sequences of numbers:
    """)
    return


@app.cell
def _():
    print("range(5):", list(range(5)))
    print("range(2, 5):", list(range(2, 5)))
    print("range(0, 10, 2):", list(range(0, 10, 2)))
    return


@app.cell
def _():
    for _i in range(5):
        print(_i)
    return


@app.cell(hide_code=True)
def _(mo):
    mo.md("""
    ## The `while` loop

    While loops continue as long as a condition is `True`.
    """)
    return


@app.cell
def _():
    _count = 0
    while _count < 5:
        print(f"The count is {_count}")
        _count += 1
    return


@app.cell(hide_code=True)
def _(mo):
    mo.md("""
    ## Controlling loop execution

    Python provides several ways to control loop execution:

    - `break`: exit the loop immediately

    - `continue`: skip to the next iteration

    These can be used with both `for` and `while` loops.
    """)
    return


@app.cell
def _():
    for _i in range(1, 6):
        if _i == 4:
            print("Breaking out of the loop.")
            break
        print(_i)
    return


@app.cell
def _():
    for _i in range(1, 6):
        if _i == 3:
            continue
        print(_i)
    return


@app.cell(hide_code=True)
def _(mo):
    mo.md("""
    ## Practical loop patterns

    Here are some common patterns you'll use with loops:

    ```python
    # Pattern 1: Accumulator
    value = 0
    for num in [1, 2, 3, 4, 5]:
        value += num

    # Pattern 2: Search
    found = False
    for item in items:
        if condition:
            found = True
            break

    # Pattern 3: Filter
    filtered = []
    for item in items:
        if condition:
            filtered.append(item)
    ```
    """)
    return


@app.cell(hide_code=True)
def _(mo):
    mo.md(r"""
    ## Next steps

    Check out the official [Python docs on loops and control flow](https://docs.python.org/3/tutorial/controlflow.html).
    """)
    return


@app.cell
def _():
    import marimo as mo
    return (mo,)


if __name__ == "__main__":
    app.run()