Add configurable class count to ScatterWidget (#33)

* Add configurable class count to ScatterWidget

Allow users to set n_classes (1-4) to configure the number of available classes. When n_classes=1, the class buttons are automatically hidden since they're unnecessary for single-class mode. Improve grid visibility in light mode.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

* Relax altair version constraint for WASM compatibility

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

* Remove ruff and altair from runtime dependencies

These are dev/demo-only tools, not runtime dependencies.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

* Remove uv.lock to avoid constraining downstream dependencies

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

* Remove pandas from dependencies - it's a lazy import

Users install pandas/polars/numpy if they want those features.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

* Remove uv.lock again

* Add uv.lock to .gitignore

* Rebuild docs with updated marimo

* cleanup

* Bump version to 0.5.0

---------

Co-authored-by: Claude Haiku 4.5 <noreply@anthropic.com>

Author: koaning

.gitignore

@@ -158,4 +158,5 @@ cython_debug/
 #  and can be added to the global gitignore or merged into this file.  For a more nuclear
 #  option (not recommended) you can uncomment the following to ignore the entire idea folder.
 esbuild
-.DS_Stores
+.DS_Stores
+uv.lock

CLAUDE.md

@@ -0,0 +1,19 @@
+# Development Notes
+
+## Setup
+
+Run `make install` to install esbuild (for bundling JavaScript) and project dependencies.
+
+## Building JavaScript
+
+After modifying files in `js/`, rebuild the bundles:
+
+```bash
+./esbuild --bundle --format=esm --outfile=drawdata/static/scatter_widget.js js/scatter_widget.js
+```
+
+Or use `make js` for watch mode during development.
+
+## Dependencies
+
+**NEVER add dev tools (ruff, pytest, etc.) or demo-only dependencies (altair, etc.) to the main `dependencies` list in pyproject.toml.** The library should only depend on what it actually needs at runtime: anywidget. Pandas, polars, and numpy are lazy imports - users install them if they want those features.

Makefile

@@ -18,4 +18,5 @@ clean:
 
 
 docs:
-	marimo -y export html-wasm --output docs --mode edit demo.py
+	rm -rf docs
+	uv run marimo -y export html-wasm --output docs --mode edit demo.py

demo.py

@@ -10,7 +10,7 @@
 
 import marimo
 
-__generated_with = "0.13.6"
+__generated_with = "0.19.6"
 app = marimo.App(width="medium")
 
 
@@ -24,19 +24,17 @@ def _():
 
 @app.cell(hide_code=True)
 def _(mo):
-    mo.md(
-        r"""
+    mo.md(r"""
     # Drawing a `ScatterChart`
 
     This notebook contains a demo of the `ScatterWidget` inside of the [drawdata](https://github.com/koaning/drawdata) library. You should see that as you draw data, that the chart below updates.
-    """
-    )
+    """)
     return
 
 
 @app.cell(hide_code=True)
 def _(ScatterWidget, mo):
-    widget = mo.ui.anywidget(ScatterWidget(height=350))
+    widget = mo.ui.anywidget(ScatterWidget(height=400, width=400))
     widget
     return (widget,)
 
@@ -62,32 +60,23 @@ def _(mo, widget):
             color="color",
         )
 
-        top_hist = (
-            base_bar
-            .encode(
-                alt.X("x:Q")
-                    # when using bins, the axis scale is set through
-                    # the bin extent, so we do not specify the scale here
-                    # (which would be ignored anyway)
-                    .bin(maxbins=30, extent=xscale.domain).stack(None).title(""),
-                alt.Y("count()").stack(None).title(""),
-                alt.Color("color:N", scale=colscale),
-            )
-            .properties(height=60)
-        )
-
-        right_hist = (
-            base_bar
-            .encode(
-                alt.Y("y:Q")
-                    .bin(maxbins=30, extent=yscale.domain)
-                    .stack(None)
-                    .title(""),
-                alt.X("count()").stack(None).title(""),
-                alt.Color("color:N"),
-            )
-            .properties(width=60)
-        )
+        top_hist = base_bar.encode(
+            alt.X("x:Q")
+            # when using bins, the axis scale is set through
+            # the bin extent, so we do not specify the scale here
+            # (which would be ignored anyway)
+            .bin(maxbins=30, extent=xscale.domain)
+            .stack(None)
+            .title(""),
+            alt.Y("count()").stack(None).title(""),
+            alt.Color("color:N", scale=colscale),
+        ).properties(height=60)
+
+        right_hist = base_bar.encode(
+            alt.Y("y:Q").bin(maxbins=30, extent=yscale.domain).stack(None).title(""),
+            alt.X("count()").stack(None).title(""),
+            alt.Color("color:N"),
+        ).properties(width=60)
 
         out = top_hist & (points | right_hist)