Update app.py

app.py

@@ -1,470 +1,190 @@
-import marimo
-
-__generated_with = "0.9.2"
-app = marimo.App()
-
-
-@app.cell
-def __():
-    import marimo as mo
-
-    mo.md("# Welcome to marimo! 🌊🍃")
-    return (mo,)
-
+# /// script
+# requires-python = ">=3.10"
+# dependencies = [
+#     "marimo",
+#     "numba==0.60.0",
+#     "numpy==2.0.2",
+#     "requests==2.32.3",
+#     "scikit-image==0.24.0",
+# ]
+# ///
 
-@app.cell
-def __(mo):
-    slider = mo.ui.slider(1, 22)
-    return (slider,)
-
-
-@app.cell
-def __(mo, slider):
-    mo.md(
-        f"""
-        marimo is a **reactive** Python notebook.
-
-        This means that unlike traditional notebooks, marimo notebooks **run
-        automatically** when you modify them or
-        interact with UI elements, like this slider: {slider}.
-
-        {"##" + "🍃" * slider.value}
-        """
-    )
-    return
+import marimo
 
-
-@app.cell(hide_code=True)
-def __(mo):
-    mo.accordion(
-        {
-            "Tip: disabling automatic execution": mo.md(
-                rf"""
-            marimo lets you disable automatic execution: just go into the
-            notebook settings and set
-
-            "Runtime > On Cell Change" to "lazy".
-
-            When the runtime is lazy, after running a cell, marimo marks its
-            descendants as stale instead of automatically running them. The
-            lazy runtime puts you in control over when cells are run, while
-            still giving guarantees about the notebook state.
-            """
-            )
-        }
-    )
-    return
+__generated_with = "0.9.6"
+app = marimo.App(width="medium")
 
 
 @app.cell(hide_code=True)
 def __(mo):
     mo.md(
         """
-        Tip: This is a tutorial notebook. You can create your own notebooks
-        by entering `marimo edit` at the command line.
-        """
-    ).callout()
-    return
+        # Seam Carving 
 
+        _Example adapted from work by [Vincent Warmerdam](https://x.com/fishnets88)_.
 
-@app.cell(hide_code=True)
-def __(mo):
-    mo.md(
-        """
-        ## 1. Reactive execution
+        ## The seam carving algorithm
+        This marimo demonstration is partially an homage to [a great video by Grant
+        Sanderson](https://www.youtube.com/watch?v=rpB6zQNsbQU) of 3Blue1Brown, which demonstrates
+        the seam carving algorithm in [Pluto.jl](https://plutojl.org/):
 
-        A marimo notebook is made up of small blocks of Python code called
-        cells.
+        <iframe width="560" height="315" src="https://www.youtube.com/embed/rpB6zQNsbQU?si=oiZclGIj2atJR47m" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
 
-        marimo reads your cells and models the dependencies among them: whenever
-        a cell that defines a global variable  is run, marimo
-        **automatically runs** all cells that reference that variable.
+        As Grant explains, the seam carving algorithm preserves the shapes of the main content in the image, while killing the "dead space": the image is resized, but the clocks and other content are not resized or deformed.
 
-        Reactivity keeps your program state and outputs in sync with your code,
-        making for a dynamic programming environment that prevents bugs before they
-        happen.
-        """
-    )
-    return
+        This notebook is a Python version of the seam carving algorithm, but it is also a
+        demonstration of marimo's [persistent caching
+        feature](https://docs.marimo.io/recipes.html#persistent-caching-for-very-expensive-computations),
+        which is helpful because the algorithm is compute intensive even when you
+        use [Numba](https://numba.pydata.org/).
 
-
-@app.cell(hide_code=True)
-def __(changed, mo):
-    (
-        mo.md(
-            f"""
-            **✨ Nice!** The value of `changed` is now {changed}.
-
-            When you updated the value of the variable `changed`, marimo
-            **reacted** by running this cell automatically, because this cell
-            references the global variable `changed`.
-
-            Reactivity ensures that your notebook state is always
-            consistent, which is crucial for doing good science; it's also what
-            enables marimo notebooks to double as tools and  apps.
-            """
-        )
-        if changed
-        else mo.md(
-            """
-            **🌊 See it in action.** In the next cell, change the value of the
-            variable  `changed` to `True`, then click the run button.
-            """
-        )
-    )
-    return
-
-
-@app.cell
-def __():
-    changed = False
-    return (changed,)
-
-
-@app.cell(hide_code=True)
-def __(mo):
-    mo.accordion(
-        {
-            "Tip: execution order": (
-                """
-                The order of cells on the page has no bearing on
-                the order in which cells are executed: marimo knows that a cell
-                reading a variable must run after the cell that  defines it. This
-                frees you to organize your code in the way that makes the most
-                sense for you.
-                """
-            )
-        }
-    )
-    return
-
-
-@app.cell(hide_code=True)
-def __(mo):
-    mo.md(
-        """
-        **Global names must be unique.** To enable reactivity, marimo imposes a
-        constraint on how names appear in cells: no two cells may define the same
-        variable.
+        Try it out by playing with the slider!
         """
     )
     return
 
 
 @app.cell(hide_code=True)
-def __(mo):
-    mo.accordion(
-        {
-            "Tip: encapsulation": (
-                """
-                By encapsulating logic in functions, classes, or Python modules,
-                you can minimize the number of global variables in your notebook.
-                """
-            )
-        }
-    )
-    return
+def __():
+    import requests
 
+    input_image = "The_Persistence_of_Memory.jpg"
+    img_data = requests.get(
+        "https://upload.wikimedia.org/wikipedia/en/d/dd/The_Persistence_of_Memory.jpg"
+    ).content
 
-@app.cell(hide_code=True)
-def __(mo):
-    mo.accordion(
-        {
-            "Tip: private variables": (
-                """
-                Variables prefixed with an underscore are "private" to a cell, so
-                they can be defined by multiple cells.
-                """
-            )
-        }
-    )
-    return
+    with open(input_image, "wb") as handler:
+        handler.write(img_data)
+    return handler, img_data, input_image, requests
 
 
 @app.cell(hide_code=True)
 def __(mo):
-    mo.md(
-        """
-        ## 2. UI elements
-
-        Cells can output interactive UI elements. Interacting with a UI
-        element **automatically triggers notebook execution**: when
-        you interact with a UI element, its value is sent back to Python, and
-        every cell that references that element is re-run.
-
-        marimo provides a library of UI elements to choose from under
-        `marimo.ui`.
-        """
-    )
+    mo.md("""## Try it!""")
     return
 
 
 @app.cell
-def __(mo):
-    mo.md("""**🌊 Some UI elements.** Try interacting with the below elements.""")
-    return
-
+def __():
+    import marimo as mo
 
-@app.cell
-def __(mo):
-    icon = mo.ui.dropdown(["🍃", "🌊", "✨"], value="🍃")
-    return (icon,)
+    slider = mo.ui.slider(
+        0.7,
+        1.0,
+        step=0.05,
+        value=1.0,
+        label="Amount of resizing to perform:",
+        show_value=True,
+    )
+    slider
+    return mo, slider
 
 
 @app.cell
-def __(icon, mo):
-    repetitions = mo.ui.slider(1, 16, label=f"number of {icon.value}: ")
-    return (repetitions,)
+def __(efficient_seam_carve, input_image, mo, slider):
+    with mo.persistent_cache("seam_carves"):
+        scale_factor = slider.value
+        result = efficient_seam_carve(input_image, scale_factor)
 
-
-@app.cell
-def __(icon, repetitions):
-    icon, repetitions
-    return
+    mo.hstack([mo.image(input_image), mo.image(result)], justify="start")
+    return result, scale_factor
 
 
 @app.cell
-def __(icon, mo, repetitions):
-    mo.md("# " + icon.value * repetitions.value)
-    return
-
-
-@app.cell(hide_code=True)
-def __(mo):
-    mo.md(
-        """
-        ## 3. marimo is just Python
-
-        marimo cells parse Python (and only Python), and marimo notebooks are
-        stored as pure Python files — outputs are _not_ included. There's no
-        magical syntax.
-
-        The Python files generated by marimo are:
-
-        - easily versioned with git, yielding minimal diffs
-        - legible for both humans and machines
-        - formattable using your tool of choice,
-        - usable as Python  scripts, with UI  elements taking their default
-        values, and
-        - importable by other modules (more on that in the future).
-        """
-    )
-    return
-
-
-@app.cell(hide_code=True)
-def __(mo):
-    mo.md(
-        """
-        ## 4. Running notebooks as apps
-
-        marimo notebooks can double as apps. Click the app window icon in the
-        bottom-right to see this notebook in "app view."
-
-        Serve a notebook as an app with `marimo run` at the command-line.
-        Of course, you can use marimo just to level-up your
-        notebooking, without ever making apps.
-        """
-    )
-    return
+def __():
+    import numpy as np
+    from numba import jit
+    from skimage import io, filters, transform
+    import time
 
 
-@app.cell(hide_code=True)
-def __(mo):
-    mo.md(
-        """
-        ## 5. The `marimo` command-line tool
+    def rgb2gray(rgb):
+        return np.dot(rgb[..., :3], [0.2989, 0.5870, 0.1140])
 
-        **Creating and editing notebooks.** Use
 
-        ```
-        marimo edit
-        ```
+    def compute_energy_map(gray):
+        return np.abs(filters.sobel_h(gray)) + np.abs(filters.sobel_v(gray))
 
-        in a terminal to start the marimo notebook server. From here
-        you can create a new notebook or edit existing ones.
 
+    @jit(nopython=True)
+    def find_seam(energy_map):
+        height, width = energy_map.shape
+        dp = energy_map.copy()
+        backtrack = np.zeros((height, width), dtype=np.int32)
 
-        **Running as apps.** Use
+        for i in range(1, height):
+            for j in range(width):
+                if j == 0:
+                    idx = np.argmin(dp[i - 1, j : j + 2])
+                    backtrack[i, j] = idx + j
+                    min_energy = dp[i - 1, idx + j]
+                elif j == width - 1:
+                    idx = np.argmin(dp[i - 1, j - 1 : j + 1])
+                    backtrack[i, j] = idx + j - 1
+                    min_energy = dp[i - 1, idx + j - 1]
+                else:
+                    idx = np.argmin(dp[i - 1, j - 1 : j + 2])
+                    backtrack[i, j] = idx + j - 1
+                    min_energy = dp[i - 1, idx + j - 1]
 
-        ```
-        marimo run notebook.py
-        ```
+                dp[i, j] += min_energy
 
-        to start a webserver that serves your notebook as an app in read-only mode,
-        with code cells hidden.
+        return backtrack
 
-        **Convert a Jupyter notebook.** Convert a Jupyter notebook to a marimo
-        notebook using `marimo convert`:
 
-        ```
-        marimo convert your_notebook.ipynb > your_app.py
-        ```
+    @jit(nopython=True)
+    def remove_seam(image, backtrack):
+        height, width, _ = image.shape
+        output = np.zeros((height, width - 1, 3), dtype=np.uint8)
+        j = np.argmin(backtrack[-1])
 
-        **Tutorials.** marimo comes packaged with tutorials:
+        for i in range(height - 1, -1, -1):
+            for k in range(3):
+                output[i, :, k] = np.delete(image[i, :, k], j)
+            j = backtrack[i, j]
 
-        - `dataflow`: more on marimo's automatic execution
-        - `ui`: how to use UI elements
-        - `markdown`: how to write markdown, with interpolated values and
-           LaTeX
-        - `plots`: how plotting works in marimo
-        - `sql`: how to use SQL
-        - `layout`: layout elements in marimo
-        - `fileformat`: how marimo's file format works
-        - `markdown-format`: for using `.md` files in marimo
-        - `for-jupyter-users`: if you are coming from Jupyter
+        return output
 
-        Start a tutorial with `marimo tutorial`; for example,
 
-        ```
-        marimo tutorial dataflow
-        ```
+    def seam_carving(image, new_width):
+        height, width, _ = image.shape
 
-        In addition to tutorials, we have examples in our
-        [our GitHub repo](https://www.github.com/marimo-team/marimo/tree/main/examples).
-        """
-    )
-    return
-
-
-@app.cell(hide_code=True)
-def __(mo):
-    mo.md(
-        """
-        ## 6. The marimo editor
-
-        Here are some tips to help you get started with the marimo editor.
-        """
-    )
-    return
+        while width > new_width:
+            gray = rgb2gray(image)
+            energy_map = compute_energy_map(gray)
+            backtrack = find_seam(energy_map)
+            image = remove_seam(image, backtrack)
+            width -= 1
 
+        return image
 
-@app.cell
-def __(mo, tips):
-    mo.accordion(tips)
-    return
 
+    def efficient_seam_carve(image_path, scale_factor):
+        img = io.imread(image_path)
+        new_width = int(img.shape[1] * scale_factor)
 
-@app.cell(hide_code=True)
-def __(mo):
-    mo.md("""## Finally, a fun fact""")
-    return
+        start_time = time.time()
+        carved_img = seam_carving(img, new_width)
+        end_time = time.time()
 
+        print(f"Seam carving completed in {end_time - start_time:.2f} seconds")
 
-@app.cell(hide_code=True)
-def __(mo):
-    mo.md(
-        """
-        The name "marimo" is a reference to a type of algae that, under
-        the right conditions, clumps together to form a small sphere
-        called a "marimo moss ball". Made of just strands of algae, these
-        beloved assemblages are greater than the sum of their parts.
-        """
+        return carved_img
+    return (
+        compute_energy_map,
+        efficient_seam_carve,
+        filters,
+        find_seam,
+        io,
+        jit,
+        np,
+        remove_seam,
+        rgb2gray,
+        seam_carving,
+        time,
+        transform,
     )
-    return
-
-
-@app.cell(hide_code=True)
-def __():
-    tips = {
-        "Saving": (
-            """
-            **Saving**
-
-            - _Name_ your app using the box at the top of the screen, or
-              with `Ctrl/Cmd+s`. You can also create a named app at the
-              command line, e.g., `marimo edit app_name.py`.
-
-            - _Save_ by clicking the save icon on the bottom right, or by
-              inputting `Ctrl/Cmd+s`. By default marimo is configured
-              to autosave.
-            """
-        ),
-        "Running": (
-            """
-            1. _Run a cell_ by clicking the play ( ▷ ) button on the top
-            right of a cell, or by inputting `Ctrl/Cmd+Enter`.
-
-            2. _Run a stale cell_  by clicking the yellow run button on the
-            right of the cell, or by inputting `Ctrl/Cmd+Enter`. A cell is
-            stale when its code has been modified but not run.
-
-            3. _Run all stale cells_ by clicking the play ( ▷ ) button on
-            the bottom right of the screen, or input `Ctrl/Cmd+Shift+r`.
-            """
-        ),
-        "Console Output": (
-            """
-            Console output (e.g., `print()` statements) is shown below a
-            cell.
-            """
-        ),
-        "Creating, Moving, and Deleting Cells": (
-            """
-            1. _Create_ a new cell above or below a given one by clicking
-                the plus button to the left of the cell, which appears on
-                mouse hover.
-
-            2. _Move_ a cell up or down by dragging on the handle to the 
-                right of the cell, which appears on mouse hover.
-
-            3. _Delete_ a cell by clicking the trash bin icon. Bring it
-                back by clicking the undo button on the bottom right of the
-                screen, or with `Ctrl/Cmd+Shift+z`.
-            """
-        ),
-        "Disabling Automatic Execution": (
-            """
-            Via the notebook settings (gear icon) or footer panel, you
-            can disable automatic execution. This is helpful when
-            working with expensive notebooks or notebooks that have
-            side-effects like database transactions.
-            """
-        ),
-        "Disabling Cells": (
-            """
-            You can disable a cell via the cell context menu.
-            marimo will never run a disabled cell or any cells that depend on it.
-            This can help prevent accidental execution of expensive computations
-            when editing a notebook.
-            """
-        ),
-        "Code Folding": (
-            """
-            You can collapse or fold the code in a cell by clicking the arrow
-            icons in the line number column to the left, or by using keyboard
-            shortcuts.
-
-            Use the command palette (`Ctrl/Cmd+k`) or a keyboard shortcut to
-            quickly fold or unfold all cells.
-            """
-        ),
-        "Code Formatting": (
-            """
-            If you have [ruff](https://github.com/astral-sh/ruff) installed,
-            you can format a cell with the keyboard shortcut `Ctrl/Cmd+b`.
-            """
-        ),
-        "Command Palette": (
-            """
-            Use `Ctrl/Cmd+k` to open the command palette.
-            """
-        ),
-        "Keyboard Shortcuts": (
-            """
-            Open the notebook menu (top-right) or input `Ctrl/Cmd+Shift+h` to
-            view a list of all keyboard shortcuts.
-            """
-        ),
-        "Configuration": (
-            """
-           Configure the editor by clicking the gears icon near the top-right
-           of the screen.
-           """
-        ),
-    }
-    return (tips,)
 
 
 if __name__ == "__main__":
-    app.run()
+    app.run()