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feat(bokeh): implement spectrogram-mel#4767

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feat(bokeh): implement spectrogram-mel#4767
github-actions[bot] merged 8 commits intomainfrom
implementation/spectrogram-mel/bokeh

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Implementation: spectrogram-mel - bokeh

Implements the bokeh version of spectrogram-mel.

File: plots/spectrogram-mel/implementations/bokeh.py

Parent Issue: #4672


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claude bot commented Mar 11, 2026

AI Review - Attempt 1/3

Image Description

The plot displays a mel-spectrogram rendered with the magma colormap (dark purple background transitioning through pink to near-white for high-intensity regions). The x-axis shows "Time (seconds)" from 0 to 4, and the y-axis shows "Frequency (Hz)" on a logarithmic scale with ticks at 50, 100, 200, 500, 1000, 2000, 4000, and 8000 Hz. A colorbar on the right is labeled "Power (dB)" ranging from approximately -70 to -20 dB. Bright horizontal bands are clearly visible at various frequency levels corresponding to the synthesized melody notes (C4, E4, G4, C5, A4, F4, D4) and their harmonics, with fundamental frequencies showing the brightest intensity. The note onsets and offsets are visible with ADSR envelope shaping. Background noise appears as a low-level dark purple texture. The lower mel bins appear heavily stretched due to the combination of linear image mapping with a log y-axis, creating visually uneven band heights. The title reads "spectrogram-mel · bokeh · pyplots.ai".

Score: 80/100

Category Score Max
Visual Quality 27 30
Design Excellence 11 20
Spec Compliance 14 15
Data Quality 14 15
Code Quality 9 10
Library Mastery 5 10
Total 80 100

Visual Quality (27/30)

  • VQ-01: Text Legibility (8/8) - All font sizes explicitly set: title=40pt, axis labels=32pt, tick labels=24pt, colorbar title=32pt, colorbar labels=24pt. All clearly readable.
  • VQ-02: No Overlap (6/6) - No overlapping text elements. Tick labels, title, axis labels all well-spaced.
  • VQ-03: Element Visibility (4/6) - Spectrogram image visible but mel bands appear blocky/pixelated due to log axis stretching the lower bins disproportionately. Higher frequency bands are compressed together.
  • VQ-04: Color Accessibility (4/4) - Magma colormap is perceptually uniform and colorblind-safe.
  • VQ-05: Layout & Canvas (3/4) - Good overall layout with colorbar on right. Minor issue: the very bottom of the plot shows a dark/black gap region, and the right margin padding could be tighter.
  • VQ-06: Axis Labels & Title (2/2) - "Time (seconds)" and "Frequency (Hz)" both descriptive with units.

Design Excellence (11/20)

  • DE-01: Aesthetic Sophistication (5/8) - Magma colormap is a strong choice for spectrograms. Log y-axis, custom tick positions at musically/acoustically meaningful frequencies. Toolbar removed for clean look. Above default but not publication-quality.
  • DE-02: Visual Refinement (3/6) - Subtle dashed grid with alpha=0.2, removed toolbar, styled outline. Background fill set to None. Some refinement visible.
  • DE-03: Data Storytelling (3/6) - The synthesized melody creates a clear visual narrative with note progressions and harmonic structure visible. The data naturally guides the viewer through the time-frequency representation.

Spec Compliance (14/15)

  • SC-01: Plot Type (5/5) - Correct mel-spectrogram visualization.
  • SC-02: Required Features (4/4) - dB conversion, sequential colormap, time/frequency axes, colorbar in dB, correct parameters (n_fft=2048, hop_length=512, n_mels=128), synthesized audio.
  • SC-03: Data Mapping (2/3) - X=time, Y=frequency correctly mapped. However, the p.image() maps mel bins linearly to the Hz range, then the log axis distorts the visual representation, causing lower bins to appear overly stretched.
  • SC-04: Title & Legend (3/3) - Title "spectrogram-mel · bokeh · pyplots.ai" matches required format. No legend needed for this plot type.

Data Quality (14/15)

  • DQ-01: Feature Coverage (5/6) - Rich audio signal with 7 notes, harmonics (4 per note), ADSR envelopes, and background noise. Shows melody progression across different frequencies. Could benefit from more variety (e.g., a wider frequency range or different timbres).
  • DQ-02: Realistic Context (5/5) - Musical notes with real frequencies (C4=261.63Hz, E4=329.63Hz, etc.) forming a recognizable melody. Realistic sample rate (22050 Hz) and duration (4s).
  • DQ-03: Appropriate Scale (4/4) - All values sensible: sample rate 22050 Hz, musical frequencies in human hearing range, 128 mel bands, appropriate FFT parameters.

Code Quality (9/10)

  • CQ-01: KISS Structure (3/3) - Clean imports → data → plot → save structure. No functions or classes.
  • CQ-02: Reproducibility (2/2) - np.random.seed(42) set at the beginning.
  • CQ-03: Clean Imports (2/2) - All imports used: numpy, bokeh (figure, export_png, models), scipy.signal.
  • CQ-04: Code Elegance (1/2) - The 256-line hardcoded magma palette is unnecessarily verbose when Bokeh provides Magma256 from bokeh.palettes. This is ~260 lines of hex strings that could be a single import.
  • CQ-05: Output & API (1/1) - Saves as plot.png and plot.html. Current API usage.

Library Mastery (5/10)

  • LM-01: Idiomatic Usage (3/5) - Uses figure(), p.image(), ColorBar, FixedTicker, export_png correctly. However, manually defining the magma palette instead of using from bokeh.palettes import Magma256 is not idiomatic Bokeh.
  • LM-02: Distinctive Features (2/5) - HTML export via output_file/save is Bokeh-specific. Uses p.image() for heatmap rendering. But doesn't leverage distinctive Bokeh features like HoverTool for interactive frequency/time readout or other interactive capabilities that make Bokeh unique.

Score Caps Applied

  • None

Strengths

  • Excellent audio synthesis with realistic musical notes, harmonics, and ADSR envelopes
  • Correct mel filterbank construction from scratch (no external dependency on librosa)
  • All font sizes explicitly set and appropriate for 4800x2700 canvas
  • Good colormap choice (magma) for spectrogram visualization
  • Proper dB conversion with floor value to avoid log(0)

Weaknesses

  • Hardcoded 256-hex-value magma palette instead of using Bokeh's built-in Magma256 from bokeh.palettes
  • The p.image() linear mapping combined with y_axis_type="log" creates visual distortion of mel bands
  • No use of Bokeh's interactive features (HoverTool showing time/frequency/power values)
  • Design could be more polished (e.g., title positioning, colorbar integration)

Issues Found

  1. CQ-04 LOW: Hardcoded 256-color palette spanning ~260 lines of code
    • Fix: Replace with from bokeh.palettes import Magma256 and use palette=Magma256
  2. LM-01 LOW: Not using Bokeh's built-in palette infrastructure
    • Fix: Use bokeh.palettes module for colormap access
  3. LM-02 LOW: Missing Bokeh's distinctive interactive capabilities
    • Fix: Add HoverTool to show time, frequency, and power values on hover
  4. VQ-03 MEDIUM: Blocky mel band rendering due to log axis + linear image mapping
    • Fix: Consider using p.rect() or p.quad() with individual mel band rectangles positioned at correct log-scale coordinates for proper visual mapping
  5. DE-01/DE-02 MEDIUM: Good but not exceptional visual design
    • Fix: Consider adjusting title styling, adding more whitespace refinement, using Bokeh's built-in theming

AI Feedback for Next Attempt

Replace the hardcoded magma palette with from bokeh.palettes import Magma256. Add a HoverTool displaying time, frequency, and power values — this is a key Bokeh-distinctive feature. Consider rendering mel bands as individual rectangles (p.quad()) instead of p.image() to avoid log-axis distortion, or at minimum ensure the image-to-axis mapping accounts for the log scale. Polish the visual design with better title positioning and colorbar integration.

Verdict: REJECTED

@github-actions github-actions bot added quality:80 Quality score 80/100 ai-rejected Quality not OK, triggers update labels Mar 11, 2026
@github-actions github-actions bot added ai-attempt-1 First repair attempt and removed ai-rejected Quality not OK, triggers update labels Mar 11, 2026
Attempt 1/3 - fixes based on AI review
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🔧 Repair Attempt 1/3

Applied fixes based on AI review feedback.

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


🤖 impl-repair

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claude bot commented Mar 11, 2026

AI Review - Attempt 2/3

Image Description

The plot displays a mel-spectrogram rendered with the Magma colormap on a dark background (#4, matching the colormap's lowest value). The x-axis shows "Time (seconds)" from 0 to 4, and the y-axis shows "Frequency (Hz)" on a logarithmic scale with fixed ticks at 50, 100, 200, 500, 1000, 2000, 4000, and 8000 Hz. A colorbar on the right is labeled "Power (dB)" ranging from approximately -70 to -20 dB. Bright horizontal bands (yellow-white through pink) are clearly visible at various frequency levels corresponding to the synthesized melody notes (C4, E4, G4, C5, A4, F4, D4) and their harmonics, with fundamentals showing the brightest intensity and harmonics progressively dimmer. Note onsets and offsets show clean ADSR envelope shaping. The mel bands are now rendered as individual quads correctly positioned on the log y-axis, eliminating the distortion seen in attempt 1. Background noise appears as low-level dark texture primarily in the lower frequencies. The title reads "spectrogram-mel · bokeh · pyplots.ai" in bold at the top left. Subtle dashed grid lines are visible at low opacity.

Score: 85/100

Category Score Max
Visual Quality 28 30
Design Excellence 12 20
Spec Compliance 15 15
Data Quality 14 15
Code Quality 9 10
Library Mastery 7 10
Total 85 100

Visual Quality (28/30)

  • VQ-01: Text Legibility (8/8) - All font sizes explicitly set: title=40pt, axis labels=32pt, tick labels=24pt, colorbar title=32pt, colorbar labels=24pt. All text clearly readable.
  • VQ-02: No Overlap (6/6) - No overlapping text elements anywhere in the plot.
  • VQ-03: Element Visibility (5/6) - Mel bands clearly visible with good contrast. The quad rendering correctly positions bands on log scale. Lower frequency bins appear slightly coarse/blocky due to narrow mel bandwidth at low frequencies, but this is largely inherent to the data.
  • VQ-04: Color Accessibility (4/4) - Magma is a perceptually uniform, colorblind-safe sequential colormap. Excellent contrast from dark to bright.
  • VQ-05: Layout & Canvas (3/4) - Good canvas utilization with colorbar on right. Min borders set appropriately. The colorbar title text is somewhat tight against the right edge; right margin could be slightly more generous.
  • VQ-06: Axis Labels & Title (2/2) - "Time (seconds)" and "Frequency (Hz)" are descriptive with units. Colorbar labeled "Power (dB)".

Design Excellence (12/20)

  • DE-01: Aesthetic Sophistication (5/8) - Magma colormap is a strong, intentional choice. Dark background (feat: add complete automation infrastructure for plot generation #4) matching the colormap floor is a professional touch. Toolbar removed, bold title with custom color, log y-axis with meaningful tick positions. Above configured default but not quite publication-grade — could benefit from more typographic refinement.
  • DE-02: Visual Refinement (4/6) - Subtle dashed grid lines (alpha=0.15), minor ticks hidden, custom outline color/width, dark background fill, generous padding. Shows clear refinement effort above defaults.
  • DE-03: Data Storytelling (3/6) - The synthesized melody creates a natural visual narrative with clearly visible note progressions, harmonic structure, and ADSR shaping. The viewer can follow the musical sequence. However, there is no explicit visual emphasis or annotation guiding the viewer to the key insight.

Spec Compliance (15/15)

  • SC-01: Plot Type (5/5) - Correct mel-spectrogram visualization with mel-scaled frequency axis.
  • SC-02: Required Features (4/4) - All required features present: dB scale conversion, sequential colormap (Magma), time x-axis in seconds, mel-scaled frequency y-axis with Hz labels at key band edges, colorbar labeled in dB, correct parameters (n_fft=2048, hop_length=512, n_mels=128), synthesized audio data.
  • SC-03: Data Mapping (3/3) - X=time, Y=frequency correctly mapped. Quads properly positioned on mel scale with log y-axis. All data visible within axis ranges.
  • SC-04: Title & Legend (3/3) - Title format correct: "spectrogram-mel · bokeh · pyplots.ai". No legend needed for this plot type.

Data Quality (14/15)

  • DQ-01: Feature Coverage (5/6) - Rich audio signal with 7 musical notes spanning C4-C5, harmonics up to 4th partial, ADSR envelopes, and background noise. Shows temporal variation, frequency structure, and intensity dynamics. Could show wider frequency variety (e.g., percussive transients or speech-like formants).
  • DQ-02: Realistic Context (5/5) - Real musical notes with correct fundamental frequencies, standard 22050 Hz sample rate, 4-second duration. Plausible and neutral audio analysis scenario.
  • DQ-03: Appropriate Scale (4/4) - All values sensible: musical frequencies in hearing range, standard mel parameters, realistic dB power range.

Code Quality (9/10)

  • CQ-01: KISS Structure (3/3) - Clean imports → data synthesis → STFT → mel filterbank → plot → save. No functions or classes.
  • CQ-02: Reproducibility (2/2) - np.random.seed(42) set at beginning.
  • CQ-03: Clean Imports (2/2) - All imports used: numpy, bokeh models/palettes/plotting/io, scipy.signal.
  • CQ-04: Code Elegance (1/2) - The nested loop building quad arrays (lines 120-128) is verbose; could be vectorized with np.repeat/np.tile. The manual mel filterbank construction is appropriate since librosa is not used, but adds significant code length.
  • CQ-05: Output & API (1/1) - Saves as plot.png via export_png and plot.html via output_file/save. Current API usage throughout.

Library Mastery (7/10)

  • LM-01: Idiomatic Usage (4/5) - Good use of ColumnDataSource, figure with quad renderer, ColorBar with LinearColorMapper, FixedTicker for mel frequencies, Magma256 from bokeh.palettes, export_png and output_file/save. Properly uses Bokeh's data-driven approach.
  • LM-02: Distinctive Features (3/5) - HoverTool with time/frequency/power readout is a genuinely distinctive Bokeh feature. HTML export alongside PNG. ColumnDataSource pattern enables the hover interactivity. These are features that couldn't easily be replicated in matplotlib.

Score Caps Applied

  • None — no caps triggered.

Strengths

  • Excellent mel filterbank construction from scratch using scipy.signal STFT, avoiding librosa dependency
  • Quad rendering correctly positions mel bands on log y-axis, fixing the visual distortion from attempt 1
  • HoverTool provides genuinely interactive readout of time, frequency, and power values
  • Dark background matching Magma colormap floor creates cohesive visual design
  • Rich audio synthesis with harmonics and ADSR envelopes produces a visually engaging spectrogram

Weaknesses

  • Design Excellence needs improvement to reach 90+: typography could be more refined, visual hierarchy could be enhanced
  • The nested loop for building quad data arrays is verbose and could be vectorized
  • No visual emphasis or annotation to guide the viewer to the key insight in the data
  • Colorbar right margin is slightly tight

Issues Found

  1. DE-01 MODERATE: Aesthetic sophistication at 5/8 — good but not publication-ready
    • Fix: Consider adding a subtitle or annotation highlighting a key musical feature, refine title positioning
  2. DE-03 MODERATE: Data storytelling at 3/6 — melody is visible but not explicitly emphasized
    • Fix: Use color or contrast to create a clearer focal point, or add subtle note labels at key frequency positions
  3. CQ-04 MINOR: Nested quad-building loop is verbose
    • Fix: Vectorize with np.repeat/np.tile for the time/mel grid construction

AI Feedback for Next Attempt

To reach 90+, focus on Design Excellence: (1) Add subtle note frequency annotations or a text overlay identifying the melody sequence to boost data storytelling (DE-03). (2) Refine the layout — increase right margin for colorbar breathing room, consider a thin separator between plot and colorbar. (3) Vectorize the quad data construction loop using np.repeat/np.tile to improve code elegance (CQ-04). (4) Consider adding a subtle y-axis label annotation at key mel frequencies (e.g., "C4", "A4") to enhance the narrative. These changes would push DE-01 to 6+, DE-03 to 4+, and CQ-04 to 2.

Verdict: REJECTED

@github-actions github-actions bot added quality:85 Quality score 85/100 ai-rejected Quality not OK, triggers update labels Mar 11, 2026
@github-actions github-actions bot added ai-attempt-2 Second repair attempt and removed ai-rejected Quality not OK, triggers update labels Mar 11, 2026
Attempt 2/3 - fixes based on AI review
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🔧 Repair Attempt 2/3

Applied fixes based on AI review feedback.

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


🤖 impl-repair

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claude bot commented Mar 11, 2026

AI Review - Attempt 3/3

Image Description

The plot displays a mel-spectrogram on a dark (#4) background using the Magma256 sequential colormap. The title "spectrogram-mel · bokeh · pyplots.ai" appears at the top left in bold dark text. The x-axis is labeled "Time (seconds)" spanning 0 to ~4 seconds, and the y-axis shows "Frequency (Hz)" on a logarithmic scale with mel-spaced tick marks at 50, 100, 200, 500, 1000, 2000, 4000, and 8000 Hz. Bright yellow-white horizontal bands clearly depict individual musical notes with visible harmonic overtones above each fundamental. A white dashed bounding box in the left portion annotates "C Major Arpeggio (C4 → E4 → G4 → C5)" in italic white text, while the right portion shows "Descending (A4 → F4 → D4)". Dotted white horizontal reference lines mark the C4 (261 Hz) and C5 (523 Hz) frequencies with bold labels at the right edge. A colorbar on the right displays "Power (dB)" ranging from approximately −100 to −20 dB. The spectrogram clearly shows the ascending arpeggio followed by a descending passage, with visible attack/release envelopes, harmonic structure, and a subtle noise floor.

Score: 92/100

Category Score Max
Visual Quality 30 30
Design Excellence 15 20
Spec Compliance 15 15
Data Quality 15 15
Code Quality 10 10
Library Mastery 7 10
Total 92 100

Visual Quality (30/30)

  • VQ-01: Text Legibility (8/8) - All font sizes explicitly set: 42pt title, 32pt axis labels, 24pt tick labels, 22pt annotations. Perfectly readable at 4800×2700.
  • VQ-02: No Overlap (6/6) - All text elements are well-positioned. Annotations placed in upper region away from dense data. No collisions.
  • VQ-03: Element Visibility (6/6) - Mel band quads are clearly visible with excellent contrast. Harmonic structure and individual notes easily distinguishable.
  • VQ-04: Color Accessibility (4/4) - Magma256 is a perceptually uniform, colorblind-safe sequential colormap. Excellent contrast against dark background.
  • VQ-05: Layout & Canvas (4/4) - Plot fills canvas well with explicitly set margins (min_border_right=180, left=130, bottom=110, top=80). Colorbar properly positioned.
  • VQ-06: Axis Labels & Title (2/2) - "Time (seconds)" and "Frequency (Hz)" — descriptive with units.

Design Excellence (15/20)

  • DE-01: Aesthetic Sophistication (6/8) - Strong design: Magma on dark background is a professional choice for spectrograms. Intentional typography hierarchy with varied font sizes and styles. White annotation overlays create visual contrast.
  • DE-02: Visual Refinement (4/6) - Subtle grid (alpha=0.12, dashed), minor ticks removed, custom background/border colors, generous margins. The light border (#fafafa) against dark plot creates a clean frame.
  • DE-03: Data Storytelling (5/6) - Excellent narrative: dashed box highlights the ascending C Major Arpeggio, separate label marks the descending passage. C4/C5 octave frequency guides provide musical context. Viewer immediately understands the melodic structure.

Spec Compliance (15/15)

  • SC-01: Plot Type (5/5) - Correct mel-spectrogram with proper mel filterbank computed from scratch using triangular filters.
  • SC-02: Required Features (4/4) - All spec requirements met: dB scale conversion, Magma sequential colormap, time x-axis in seconds, mel-scaled y-axis with Hz labels at key band edges, colorbar labeled in dB, n_fft=2048, hop_length=512, n_mels=128.
  • SC-03: Data Mapping (3/3) - X=time in seconds, Y=mel-frequency in Hz on log scale. All data visible within axes.
  • SC-04: Title & Legend (3/3) - Title "spectrogram-mel · bokeh · pyplots.ai" matches required format. No legend needed (colorbar serves as the scale reference).

Data Quality (15/15)

  • DQ-01: Feature Coverage (6/6) - Rich synthesized audio: 7 notes with 4 harmonics each, attack/release envelopes, background noise. Shows harmonic structure, temporal evolution, and mel-scale frequency compression.
  • DQ-02: Realistic Context (5/5) - Musical melody context (C Major Arpeggio + descending passage) is realistic, comprehensible, and neutral. Frequencies and structure match real musical audio.
  • DQ-03: Appropriate Scale (4/4) - Sample rate 22050 Hz, 4-second duration, musical frequencies 261–523 Hz with harmonics up to ~2000 Hz — all perfectly realistic for audio analysis.

Code Quality (10/10)

  • CQ-01: KISS Structure (3/3) - Clean imports → data generation → STFT → mel filterbank → plotting → save structure. No functions or classes.
  • CQ-02: Reproducibility (2/2) - np.random.seed(42) set at the start.
  • CQ-03: Clean Imports (2/2) - All imports are used: numpy, bokeh models, Magma256, scipy.signal.
  • CQ-04: Code Elegance (2/2) - Appropriate complexity for mel-spectrogram computation. Vectorized quad construction with np.repeat/np.tile. No fake functionality.
  • CQ-05: Output & API (1/1) - Saves as plot.png via export_png and plot.html via save. Current Bokeh API.

Library Mastery (7/10)

  • LM-01: Idiomatic Usage (4/5) - Excellent use of ColumnDataSource, quad glyphs for spectrogram rendering, layout system with BoxAnnotation/Label/Span, ColorBar with LinearColorMapper, FixedTicker for mel-spaced ticks.
  • LM-02: Distinctive Features (3/5) - HoverTool with formatted tooltips (time, frequency, power readout), HTML export alongside PNG, BoxAnnotation for region highlighting — these are distinctively Bokeh features not easily replicated in static libraries.

Score Caps Applied

  • None — no caps triggered

Strengths

  • Mel filterbank computed from scratch with proper triangular filters — demonstrates deep understanding of audio signal processing
  • Magma colormap on dark background is the industry-standard choice for spectrograms, looks professional
  • Musical narrative (C Major Arpeggio → descending passage) with annotations creates excellent data storytelling
  • All font sizes explicitly scaled for 4800×2700 canvas with careful typography hierarchy
  • Vectorized quad construction is efficient and clean
  • HoverTool adds genuine interactive value for the HTML export

Weaknesses

  • LM-01 could reach 5/5 with use of Bokeh's built-in image glyph (p.image) instead of manually constructing quads, which would be more idiomatic for heatmap-style data
  • DE-02 could benefit from removing the outline line entirely for a cleaner aesthetic

Issues Found

None — implementation meets approval threshold.

AI Feedback for Next Attempt

N/A — Implementation approved at 92/100. Strong execution across all categories with particularly excellent spec compliance, data quality, and visual storytelling through musical annotations.

Verdict: APPROVED

@github-actions github-actions bot added quality:92 Quality score 92/100 ai-approved Quality OK, ready for merge labels Mar 11, 2026
@github-actions github-actions bot merged commit 227cdc3 into main Mar 11, 2026
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@github-actions github-actions bot deleted the implementation/spectrogram-mel/bokeh branch March 11, 2026 20:09
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