update(area-basic): letsplot — comprehensive quality review (#4179)

## Summary

Updated **letsplot** implementation for **area-basic**.

### Changes
- Switched from numeric day_num to proper datetime x-axis with
scale_x_datetime
- Added interactive tooltips via layer_tooltips()
- Added scale_y_continuous with limits starting at 0
- Subtler grid lines (size 0.3)

## Test Plan

- [x] Preview images uploaded to GCS staging
- [x] Implementation file passes ruff format/check
- [x] Metadata YAML updated with current versions
- [ ] Automated review triggered

---
Generated with [Claude Code](https://claude.com/claude-code) `/update`
command

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: MarkusNeusinger

plots/area-basic/implementations/letsplot.py

@@ -1,7 +1,7 @@
 """ pyplots.ai
 area-basic: Basic Area Chart
-Library: letsplot 4.8.1 | Python 3.13.11
-Quality: 91/100 | Created: 2025-12-23
+Library: letsplot 4.8.2 | Python 3.14.2
+Quality: 95/100 | Created: 2025-12-23
 """
 
 import numpy as np
@@ -23,23 +23,31 @@
 visitors = np.clip(visitors, 2000, None).astype(int)
 
 df = pd.DataFrame({"date": days, "visitors": visitors})
-df["day_num"] = np.arange(1, len(df) + 1)
 
 # Plot
 plot = (
-    ggplot(df, aes(x="day_num", y="visitors"))  # noqa: F405
-    + geom_area(fill="#306998", alpha=0.4)  # noqa: F405
+    ggplot(df, aes(x="date", y="visitors"))  # noqa: F405
+    + geom_area(  # noqa: F405
+        fill="#306998",
+        alpha=0.4,
+        tooltips=layer_tooltips()  # noqa: F405
+        .line("@visitors visitors")
+        .format("date", "%b %d, %Y")
+        .line("@date"),
+    )
     + geom_line(color="#306998", size=2)  # noqa: F405
+    + scale_x_datetime(format="%b %d")  # noqa: F405
+    + scale_y_continuous(limits=[0, None])  # noqa: F405
     + labs(  # noqa: F405
-        x="Day of Month", y="Daily Visitors", title="area-basic · letsplot · pyplots.ai"
+        x="Date", y="Daily Visitors", title="area-basic · letsplot · pyplots.ai"
     )
     + ggsize(1600, 900)  # noqa: F405
     + theme_minimal()  # noqa: F405
     + theme(  # noqa: F405
         axis_text=element_text(size=16),  # noqa: F405
         axis_title=element_text(size=20),  # noqa: F405
         plot_title=element_text(size=24),  # noqa: F405
-        panel_grid=element_line(color="#CCCCCC", size=0.5, linetype="dashed"),  # noqa: F405
+        panel_grid=element_line(color="#CCCCCC", size=0.3, linetype="dashed"),  # noqa: F405
     )
 )
 

plots/area-basic/metadata/letsplot.yaml

@@ -1,101 +1,103 @@
 library: letsplot
 specification_id: area-basic
 created: '2025-12-23T00:49:34Z'
-updated: '2025-12-23T01:21:34Z'
-generated_by: claude-opus-4-5-20251101
+updated: '2026-02-11T22:27:56Z'
+generated_by: claude-opus-4-6
 workflow_run: 20447993117
 issue: 0
-python_version: 3.13.11
-library_version: 4.8.1
+python_version: 3.14.2
+library_version: 4.8.2
 preview_url: https://storage.googleapis.com/pyplots-images/plots/area-basic/letsplot/plot.png
 preview_thumb: https://storage.googleapis.com/pyplots-images/plots/area-basic/letsplot/plot_thumb.png
 preview_html: https://storage.googleapis.com/pyplots-images/plots/area-basic/letsplot/plot.html
-quality_score: 91
+quality_score: 95
 impl_tags:
   dependencies: []
   techniques:
-    - layer-composition
+  - layer-composition
+  - hover-tooltips
+  - html-export
   patterns:
-    - data-generation
-  dataprep: []
+  - data-generation
+  dataprep:
+  - time-series
   styling:
-    - alpha-blending
-    - grid-styling
+  - alpha-blending
+  - grid-styling
 review:
   strengths:
-  - Excellent realistic data generation with trend, weekly cyclical pattern, and noise
-  - Clean ggplot2-style code using geom_area and geom_line combination
-  - Proper export with scale=3 for high resolution (4800x2700 px)
-  - Semi-transparent fill (alpha=0.4) for good readability as spec recommends
-  - Saves both PNG and HTML for interactive version
+  - Excellent data generation with realistic weekly cyclical pattern plus upward trend
+    and noise — perfectly demonstrates area chart strengths
+  - 'Good use of letsplot-specific features: layer_tooltips() with formatted hover
+    information and HTML interactive export'
+  - Clean, well-structured code following KISS principle with proper seed for reproducibility
+  - Semi-transparent fill (alpha=0.4) balances between showing the area weight and
+    maintaining readability
+  - Text sizing follows library guidelines perfectly (24/20/16pt hierarchy)
   weaknesses:
-  - Y-axis starts at 0 creating large empty space below data (consider starting from
-    minimum value or using scale_y_continuous with limits)
-  - Uses numeric day_num instead of actual dates; could use scale_x_datetime for proper
-    date axis formatting
-  - Grid styling could be more subtle (add alpha to panel_grid)
-  image_description: The plot shows a basic area chart displaying daily website visitors
-    over 30 days. The filled area uses a semi-transparent blue color (#306998 with
-    alpha 0.4), with a darker blue line (same color, size=2) tracing the top boundary
-    of the area. The chart has a light gray dashed grid in the background. The title
-    "area-basic · letsplot · pyplots.ai" appears at the top. The x-axis is labeled
-    "Day of Month" (ranging from 0 to 30), and the y-axis is labeled "Daily Visitors"
-    (ranging from 0 to 8,000). The data shows a realistic pattern with an upward trend
-    over the month, weekly cyclical variations (approximately 7-day periods visible
-    as peaks and valleys), and some random noise. Values start around 5,000 visitors
-    and end near 7,500.
+  - Y-axis starting at 0 creates substantial empty space below the data range (~4300-7600),
+    compressing the visual representation of variation in the upper portion of the
+    chart
+  - Right edge Jan 31 label appears slightly clipped
+  image_description: The plot displays a basic area chart titled "area-basic · letsplot
+    · pyplots.ai". The x-axis shows dates from Jan 01 to Jan 31 labeled "Date", and
+    the y-axis shows "Daily Visitors" ranging from 0 to 8,000. The area beneath the
+    line is filled with semi-transparent blue (#306998, alpha ~0.4) with a solid darker
+    blue outline (line width 2). The data exhibits a clear cyclical weekly pattern
+    (peaks and troughs every ~7 days) overlaid on an upward trend from ~5,000 to ~7,500
+    visitors. Dashed light-gray gridlines aid value estimation. The theme is minimal
+    with clean white background. The chart uses the full canvas width well in landscape
+    orientation.
   criteria_checklist:
     visual_quality:
-      score: 37
+      score: 36
       max: 40
       items:
       - id: VQ-01
         name: Text Legibility
         score: 10
         max: 10
         passed: true
-        comment: Title, axis labels, and tick marks are all clearly readable with
-          appropriate font sizes (title=24, axis_title=20, axis_text=16)
+        comment: Title at 24pt, axis labels at 20pt, tick text at 16pt — all perfectly
+          readable
       - id: VQ-02
         name: No Overlap
         score: 8
         max: 8
         passed: true
-        comment: No overlapping text elements anywhere in the plot
+        comment: No overlapping text; date labels well-spaced
       - id: VQ-03
         name: Element Visibility
-        score: 8
+        score: 6
         max: 8
         passed: true
-        comment: Area fill and line are well-sized and clearly visible; alpha=0.4
-          is appropriate
+        comment: Area fill and line visible, but y-axis starting at 0 means data (~4300-7600)
+          occupies only the upper portion; variation is somewhat compressed
       - id: VQ-04
         name: Color Accessibility
         score: 5
         max: 5
         passed: true
-        comment: Single blue color scheme is colorblind-safe
+        comment: Single blue color, fully colorblind-safe
       - id: VQ-05
         name: Layout Balance
-        score: 4
+        score: 3
         max: 5
-        passed: true
-        comment: Good proportions overall, though the y-axis starts at 0 which creates
-          a large empty area below the data (values range ~4,300-7,600)
+        passed: false
+        comment: Y-axis at 0 creates large empty zone below data; Jan 31 label slightly
+          clipped at right edge
       - id: VQ-06
         name: Axis Labels
-        score: 1
+        score: 2
         max: 2
         passed: true
-        comment: Labels are descriptive ("Day of Month", "Daily Visitors") but lack
-          units
+        comment: Date and Daily Visitors are descriptive labels
       - id: VQ-07
         name: Grid & Legend
-        score: 1
+        score: 2
         max: 2
         passed: true
-        comment: Grid is visible with dashed style but could be more subtle (alpha
-          not apparent in grid styling)
+        comment: Dashed light-gray gridlines are subtle and helpful; no legend needed
     spec_compliance:
       score: 25
       max: 25
@@ -105,19 +107,20 @@ review:
         score: 8
         max: 8
         passed: true
-        comment: Correct area chart type with filled area below the line
+        comment: Correct basic area chart
       - id: SC-02
         name: Data Mapping
         score: 5
         max: 5
         passed: true
-        comment: X (day number) and Y (visitors) correctly mapped
+        comment: X=datetime, Y=numeric correctly assigned
       - id: SC-03
         name: Required Features
         score: 5
         max: 5
         passed: true
-        comment: Has semi-transparent fill (alpha 0.4), gridlines, clear axis labels
+        comment: Semi-transparent fill (alpha=0.4), gridlines, clear axis labels all
+          present
       - id: SC-04
         name: Data Range
         score: 3
@@ -129,38 +132,37 @@ review:
         score: 2
         max: 2
         passed: true
-        comment: No legend needed for single-series area chart
+        comment: No legend needed for single series
       - id: SC-06
         name: Title Format
         score: 2
         max: 2
         passed: true
-        comment: Correct format "area-basic · letsplot · pyplots.ai"
+        comment: area-basic · letsplot · pyplots.ai matches required format
     data_quality:
-      score: 19
+      score: 20
       max: 20
       items:
       - id: DQ-01
         name: Feature Coverage
-        score: 7
+        score: 8
         max: 8
         passed: true
-        comment: Shows trend, cyclical pattern, and variation well; could show more
-          dramatic peaks/valleys
+        comment: Shows upward trend, weekly cyclical pattern, and random noise — excellent
+          coverage for area chart
       - id: DQ-02
         name: Realistic Context
         score: 7
         max: 7
         passed: true
-        comment: Website visitors is the exact example from spec; daily pattern with
-          weekly cycles is realistic
+        comment: Daily website visitors over a month — realistic, neutral scenario
+          matching spec example
       - id: DQ-03
         name: Appropriate Scale
         score: 5
         max: 5
         passed: true
-        comment: Visitor counts (2,000-8,000 range) are realistic for a medium-sized
-          website
+        comment: 4300-7600 daily visitors is realistic for a medium website
     code_quality:
       score: 10
       max: 10
@@ -170,41 +172,40 @@ review:
         score: 3
         max: 3
         passed: true
-        comment: Simple imports → data → plot → save structure, no functions/classes
+        comment: Clean imports → data → plot → save structure
       - id: CQ-02
         name: Reproducibility
         score: 3
         max: 3
         passed: true
-        comment: Uses np.random.seed(42)
+        comment: np.random.seed(42) present
       - id: CQ-03
         name: Clean Imports
         score: 2
         max: 2
         passed: true
-        comment: All imports are used (numpy, pandas, lets_plot)
+        comment: All imports used
       - id: CQ-04
         name: No Deprecated API
         score: 1
         max: 1
         passed: true
-        comment: Uses current lets-plot API
+        comment: Current API usage
       - id: CQ-05
         name: Output Correct
         score: 1
         max: 1
         passed: true
-        comment: Saves as plot.png and plot.html
+        comment: Saves as plot.png
     library_features:
-      score: 0
+      score: 4
       max: 5
       items:
       - id: LF-01
-        name: Uses distinctive library features
-        score: 0
+        name: Distinctive Features
+        score: 4
         max: 5
-        passed: false
-        comment: Implementation uses basic ggplot grammar but doesn't leverage lets-plot
-          specific features like interactive tooltips, scale_x_datetime for proper
-          date handling, or other distinctive capabilities
+        passed: true
+        comment: Good use of layer_tooltips() with custom date formatting, scale_x_datetime,
+          ggsize(), HTML export; could add geom_smooth or gradient fill for more distinctiveness
   verdict: APPROVED