feat(letsplot): implement candlestick-volume

[github-actions]

Implementation: candlestick-volume - letsplot

Implements the letsplot version of candlestick-volume.

File: plots/candlestick-volume/implementations/letsplot.py

Parent Issue: #3068

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🤖 impl-generate workflow

[claude]

AI Review - Attempt 1/3

Image Description

The plot displays a dual-pane financial chart with a candlestick chart in the upper pane (occupying roughly 70% of vertical space) and a volume bar chart in the lower pane (roughly 30%). The title reads "candlestick-volume · letsplot · pyplots.ai" in black text at the top. The upper pane shows 60 days of price data ranging from approximately $125 to $165, with green candlesticks indicating up days (close ≥ open) and red candlesticks indicating down days. The candlesticks clearly show wicks (high-low lines) and bodies (open-close). The lower pane shows volume bars with the same green/red color scheme matching the price direction. The x-axis is labeled "Trading Day (Jan-Mar 2024)" ranging from 0 to 60, and the y-axis labels are "Price ($)" and "Volume (M)" respectively. Grid lines are subtle gray. The overall layout is clean with proper proportions between the two panes.

Quality Score: 85/100

Criteria Checklist

Visual Quality (34/40 pts)

• VQ-01: Text Legibility (9/10) - Title and labels are readable, good font sizes
• VQ-02: No Overlap (8/8) - No overlapping text elements
• VQ-03: Element Visibility (7/8) - Candlesticks and bars are clearly visible, well-sized
• VQ-04: Color Accessibility (2/5) - Uses red/green which is problematic for colorblind users
• VQ-05: Layout Balance (5/5) - Excellent 70/30 split as spec requires, good canvas utilization
• VQ-06: Axis Labels (2/2) - Descriptive with units: "Price ($)", "Volume (M)"
• VQ-07: Grid & Legend (1/2) - Grid is subtle and good, but no legend (direction colors unexplained)

Spec Compliance (21/25 pts)

• SC-01: Plot Type (8/8) - Correct candlestick + volume dual-pane chart
• SC-02: Data Mapping (5/5) - OHLC and volume correctly mapped
• SC-03: Required Features (3/5) - Missing crosshair/cursor spanning both panes as spec requires
• SC-04: Data Range (3/3) - All data visible
• SC-05: Legend Accuracy (0/2) - No legend showing what green/red means
• SC-06: Title Format (2/2) - Correct format: candlestick-volume · letsplot · pyplots.ai

Data Quality (18/20 pts)

• DQ-01: Feature Coverage (7/8) - Shows both bullish and bearish days, price trends, volume variation
• DQ-02: Realistic Context (7/7) - Stock price data with realistic movement patterns
• DQ-03: Appropriate Scale (4/5) - Prices around $125-165 realistic; volume in millions appropriate

Code Quality (9/10 pts)

• CQ-01: KISS Structure (3/3) - Clean imports → data → plot → save structure
• CQ-02: Reproducibility (3/3) - Uses np.random.seed(42)
• CQ-03: Clean Imports (2/2) - Only numpy, pandas, lets_plot used
• CQ-04: No Deprecated API (0/1) - Uses deprecated GGBunch-style approach via gggrid (minor)
• CQ-05: Output Correct (1/1) - Saves as plot.png

Library Features (3/5 pts)

• LF-01: Uses distinctive library features (3/5) - Uses gggrid for layout, ggplot grammar, but no interactive features like tooltips

Strengths

• Excellent dual-pane layout with proper 70/30 vertical split matching spec requirements
• Clean candlestick implementation using geom_segment for both wicks and bodies
• Volume bars correctly color-coded to match candlestick direction
• Good use of lets-plot's ggplot grammar and gggrid for combining plots
• Realistic synthetic stock data with proper OHLC relationship
• Proper title format following pyplots.ai convention
• Subtle grid lines that don't distract from data

Weaknesses

• Red/green color scheme is not colorblind-safe; should use colorblind-friendly alternatives (e.g., blue/orange)
• Missing crosshair/cursor feature spanning both panes as specified in the requirements
• No legend explaining what green and red colors represent (up/down days)
• X-axis shows numeric index instead of actual dates which would be more meaningful

Verdict: REJECTED

[github-actions]

🔧 Repair Attempt 1/3

Applied fixes based on AI review feedback.

Status: Repair completed, re-triggering review...

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🤖 impl-repair

[claude]

AI Review - Attempt 2/3

Image Description

The plot displays a professional dual-pane financial chart with a candlestick chart occupying the upper ~70% and volume bars in the lower ~30%. The title "candlestick-volume · letsplot · pyplots.ai" is clearly displayed at the top. Blue candlesticks represent up days (Close ≥ Open) and orange candlesticks represent down days (Close < Open). The price chart shows a realistic downtrend from ~$165 to ~$130 over 60 trading days (Jan-Mar 2024). Volume bars below use matching colors synchronized with the candlesticks. The legend is positioned at top but appears partially cut off on the right edge. Grid lines are subtle gray. Both panes share a properly aligned x-axis with date labels.

Quality Score: 87/100

Criteria Checklist

Visual Quality (35/40 pts)

• VQ-01: Text Legibility (9/10) - Title, axis labels, and tick marks are clearly readable, good font sizes
• VQ-02: No Overlap (6/8) - Minor issue: legend text cut off on right side ("Open)" truncated)
• VQ-03: Element Visibility (8/8) - Candlesticks and volume bars are well-sized and clearly visible
• VQ-04: Color Accessibility (5/5) - Blue/orange palette is colorblind-safe
• VQ-05: Layout Balance (5/5) - 70/30 split as per spec, good canvas utilization
• VQ-06: Axis Labels (2/2) - "Price ($)" with units, "Volume" descriptive, "Date (2024)" informative
• VQ-07: Grid & Legend (0/2) - Legend partially cut off, disrupts professional appearance

Spec Compliance (24/25 pts)

• SC-01: Plot Type (8/8) - Correct candlestick + volume dual-pane chart
• SC-02: Data Mapping (5/5) - OHLC correctly mapped to candlesticks, volume to bars
• SC-03: Required Features (4/5) - Shared x-axis, matching colors, proper ratio; missing crosshair
• SC-04: Data Range (3/3) - All data visible, no clipping
• SC-05: Legend Accuracy (2/2) - Legend labels correctly describe up/down days
• SC-06: Title Format (2/2) - Follows {spec-id} · {library} · pyplots.ai format

Data Quality (18/20 pts)

• DQ-01: Feature Coverage (7/8) - Shows both bullish and bearish candles, volume correlation
• DQ-02: Realistic Context (7/7) - Stock price data with realistic trends and volatility
• DQ-03: Appropriate Scale (4/5) - Price range $125-165 and 5M volume are realistic

Code Quality (10/10 pts)

• CQ-01: KISS Structure (3/3) - Clean linear flow: imports → data → plot → save
• CQ-02: Reproducibility (3/3) - np.random.seed(42) set
• CQ-03: Clean Imports (2/2) - Only necessary imports used
• CQ-04: No Deprecated API (1/1) - Uses gggrid instead of deprecated GGBunch
• CQ-05: Output Correct (1/1) - Saves as plot.png and plot.html

Library Features (0/5 pts)

• LF-01: Uses distinctive library features (0/5) - Uses basic geom_segment and geom_bar; does not leverage lets-plot interactive features like tooltips or cursor/crosshair

Strengths

• Excellent dual-pane layout using gggrid with proper 70/30 height ratio
• Colorblind-safe blue/orange palette applied consistently to both candlesticks and volume bars
• Clean KISS code structure with good data generation for realistic price movements
• Proper use of geom_segment for both wicks and bodies creates recognizable candlesticks
• Correct title format and descriptive axis labels with units

Weaknesses

• Legend is cut off on the right edge, truncating "Down Day (Close < Open)" text
• No crosshair or cursor spanning both panes as mentioned in the specification
• Volume axis uses scientific notation (5·10⁶) which is less intuitive than formatted numbers

Verdict: REJECTED

[github-actions]

🔧 Repair Attempt 2/3

Applied fixes based on AI review feedback.

Status: Repair completed, re-triggering review...

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🤖 impl-repair

[claude]

AI Review - Attempt 3/3

Image Description

The plot displays a professional dual-pane candlestick chart with synchronized volume bars. The upper pane (~70% height) shows OHLC candlesticks with blue color for "Up Day" and orange for "Down Day", depicting a stock declining from ~$165 to ~$127 over 60 trading days (Jan-Mar 2024). Wicks are visible extending from candlestick bodies. The lower pane (~30% height) shows corresponding volume bars using the same color scheme, with human-readable y-axis labels (3.9M, 6.1M, 8.3M). The title "candlestick-volume · letsplot · pyplots.ai" appears at top, with a horizontal legend showing "Direction" with Up Day/Down Day entries. Both panes share a common x-axis showing dates. Grid lines are subtle gray. The layout is well-balanced with good canvas utilization.

Quality Score: 91/100

Criteria Checklist

Visual Quality (36/40 pts)

• VQ-01: Text Legibility (10/10) - Title ~24pt, axis labels ~20pt, tick marks ~16pt, all perfectly readable
• VQ-02: No Overlap (8/8) - No overlapping text elements, date labels well-spaced
• VQ-03: Element Visibility (7/8) - Candlesticks are visible with appropriate sizing; wicks could be slightly thicker for better visibility
• VQ-04: Color Accessibility (5/5) - Blue (#0077BB) and orange (#EE7733) are colorblind-safe
• VQ-05: Layout Balance (4/5) - Good 70/30 split as specified; slight gap between panes but acceptable
• VQ-06: Axis Labels (2/2) - "Price ($)" and "Volume (shares)" with units, "Date (2024)" is descriptive
• VQ-07: Grid & Legend (0/2) - Grid is subtle, but legend positioning at top overlaps with data area conceptually; minor grid alignment issue between panes

Spec Compliance (24/25 pts)

• SC-01: Plot Type (8/8) - Correct candlestick chart with volume bars in dual-pane layout
• SC-02: Data Mapping (5/5) - Date on X, OHLC prices correctly mapped, volume on lower pane
• SC-03: Required Features (4/5) - Has shared x-axis, color-coded volume, proper pane ratio; no crosshair cursor in PNG (only available in HTML)
• SC-04: Data Range (3/3) - All data visible, axes show complete range
• SC-05: Legend Accuracy (2/2) - "Direction" legend with "Up Day"/"Down Day" is accurate
• SC-06: Title Format (2/2) - "candlestick-volume · letsplot · pyplots.ai" is correct

Data Quality (18/20 pts)

• DQ-01: Feature Coverage (7/8) - Shows both bullish (blue) and bearish (orange) candles, varying volume, overall downtrend with some recovery; good mix but could show more dramatic reversals
• DQ-02: Realistic Context (7/7) - Stock price data with realistic volatility and volume correlation
• DQ-03: Appropriate Scale (4/5) - Prices ($127-$165) and volumes (4M-8M) are realistic; volume format is human-readable

Code Quality (8/10 pts)

• CQ-01: KISS Structure (1/3) - Has helper function format_volume() which breaks KISS principle (no functions/classes rule)
• CQ-02: Reproducibility (3/3) - Uses np.random.seed(42)
• CQ-03: Clean Imports (2/2) - Only numpy, pandas, lets_plot used
• CQ-04: No Deprecated API (1/1) - Uses modern gggrid instead of deprecated GGBunch
• CQ-05: Output Correct (1/1) - Saves as plot.png and plot.html

Library Features (5/5 pts)

• LF-01: Uses distinctive library features (5/5) - Uses gggrid for multi-panel layout, ggplot2 grammar, scale_color_manual, theme customization, ggsave with scale parameter

Strengths

• Excellent dual-pane layout using gggrid with proper 70/30 height ratio as specified
• Colorblind-safe color scheme (blue/orange) applied consistently across both panes
• Human-readable volume labels (3.9M, 6.1M, 8.3M) improve readability
• Clean implementation of candlesticks using geom_segment for both wicks and bodies
• Proper ggplot2 grammar of graphics style leveraging lets-plot's strengths
• Correct title format and descriptive axis labels with units

Weaknesses

• Helper function format_volume() violates KISS principle (code should be flat script)
• Crosshair cursor mentioned in comments but only available in HTML output, not PNG
• Minor visual gap between the two panes could be tighter

Verdict: APPROVED

This implementation meets the quality threshold (≥90) on attempt 3/3. The plot effectively demonstrates a candlestick chart with volume using lets-plot's grammar of graphics approach. The dual-pane layout, color scheme, and data representation all meet spec requirements. The minor KISS violation from the helper function is acceptable given the improved readability it provides for volume labels.