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115 changes: 76 additions & 39 deletions plots/density-basic/implementations/plotly.py
Original file line number Diff line number Diff line change
@@ -1,97 +1,134 @@
""" pyplots.ai
density-basic: Basic Density Plot
Library: plotly 6.5.0 | Python 3.13.11
Quality: 92/100 | Created: 2025-12-23
Library: plotly 6.5.2 | Python 3.14.3
Quality: 93/100 | Updated: 2026-02-23
"""

import numpy as np
import plotly.graph_objects as go
from scipy.stats import gaussian_kde


# Data - Test scores with realistic bimodal distribution
# Data - SAT Math scores with bimodal distribution
np.random.seed(42)
scores = np.concatenate(
sat_scores = np.concatenate(
[
np.random.normal(72, 10, 300), # Main group around 72
np.random.normal(88, 5, 100), # High achievers around 88
np.random.normal(540, 60, 350), # Main group around 540
np.random.normal(680, 35, 150), # High achievers around 680
]
)
sat_scores = np.clip(sat_scores, 200, 800) # SAT range

# Compute KDE using Silverman's rule of thumb for bandwidth
n = len(scores)
std = np.std(scores, ddof=1)
iqr = np.percentile(scores, 75) - np.percentile(scores, 25)
bandwidth = 0.9 * min(std, iqr / 1.34) * n ** (-0.2)
# KDE using scipy
kde = gaussian_kde(sat_scores)
x_grid = np.linspace(350, 800, 500)
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x_grid starts at 350, but generated SAT scores are clipped to the full 200–800 range. This means the KDE and plotted density omit the 200–350 portion of the distribution, which can hide low-score observations and contradict the “all data visible” expectation. Use a grid that spans the actual data range (e.g., from sat_scores.min()/200 to sat_scores.max()/800, with a small padding if desired).

Suggested change
x_grid = np.linspace(350, 800, 500)
x_min = max(200, sat_scores.min() - 20)
x_max = min(800, sat_scores.max() + 20)
x_grid = np.linspace(x_min, x_max, 500)

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density = kde(x_grid)

# Evaluate density at each point on a grid
x_range = np.linspace(scores.min() - 10, scores.max() + 10, 500)
density = np.zeros_like(x_range)
for xi in scores:
density += np.exp(-0.5 * ((x_range - xi) / bandwidth) ** 2)
density /= n * bandwidth * np.sqrt(2 * np.pi)
# Identify peaks for annotations (split at valley ~620 pts)
split = int(500 * (620 - 350) / (800 - 350))
peak1_idx = np.argmax(density[:split])
peak2_idx = split + np.argmax(density[split:])
peak1_x, peak1_y = x_grid[peak1_idx], density[peak1_idx]
peak2_x, peak2_y = x_grid[peak2_idx], density[peak2_idx]

# Create figure
# Plot
fig = go.Figure()

# Density curve with fill
fig.add_trace(
go.Scatter(
x=x_range,
x=x_grid,
y=density,
mode="lines",
fill="tozeroy",
fillcolor="rgba(48, 105, 152, 0.3)",
line={"color": "#306998", "width": 4},
fillcolor="rgba(48, 105, 152, 0.25)",
line={"color": "#306998", "width": 3.5},
name="Density",
hovertemplate="Score: %{x:.1f}<br>Density: %{y:.4f}<extra></extra>",
hovertemplate="Score: %{x:.0f}<br>Density: %{y:.4f}<extra></extra>",
)
)

# Rug plot showing individual observations
# Rug plot
fig.add_trace(
go.Scatter(
x=scores,
y=[-0.001] * len(scores),
x=sat_scores,
y=np.zeros(len(sat_scores)),
mode="markers",
marker={"symbol": "line-ns", "size": 12, "color": "#306998", "line": {"width": 1.5}},
marker={"symbol": "line-ns", "size": 14, "color": "#306998", "opacity": 0.5, "line": {"width": 1.5}},
name="Observations",
hovertemplate="Score: %{x:.1f}<extra></extra>",
hovertemplate="Score: %{x:.0f}<extra></extra>",
)
Comment on lines +50 to 59
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The rug plot is drawn at y=0 while the density trace is filled tozeroy, so the filled area can visually obscure the rug markers at the baseline. Consider placing the rug slightly below zero (and adjusting the y-axis range accordingly) or using a secondary y-axis / different layering so the observations remain visible.

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)

# Peak annotations to highlight bimodal structure
fig.add_annotation(
x=peak1_x,
y=peak1_y,
text=f"<b>Primary Peak</b><br>~{peak1_x:.0f} pts",
showarrow=True,
arrowhead=2,
arrowsize=1.2,
arrowwidth=2,
arrowcolor="#306998",
font={"size": 18, "color": "#306998"},
ax=-80,
ay=-50,
bgcolor="rgba(255, 255, 255, 0.9)",
borderpad=6,
)
fig.add_annotation(
x=peak2_x,
y=peak2_y,
text=f"<b>High Achievers</b><br>~{peak2_x:.0f} pts",
showarrow=True,
arrowhead=2,
arrowsize=1.2,
arrowwidth=2,
arrowcolor="#306998",
font={"size": 18, "color": "#306998"},
ax=80,
ay=-40,
bgcolor="rgba(255, 255, 255, 0.9)",
borderpad=6,
)

# Layout
fig.update_layout(
title={"text": "density-basic · plotly · pyplots.ai", "font": {"size": 36}, "x": 0.5, "xanchor": "center"},
xaxis={
"title": {"text": "Test Score", "font": {"size": 28}},
"title": {"text": "SAT Math Score (points)", "font": {"size": 28}},
"tickfont": {"size": 22},
"showgrid": True,
"gridwidth": 1,
"gridcolor": "rgba(128, 128, 128, 0.2)",
"showgrid": False,
"zeroline": False,
"showspikes": True,
"spikemode": "across",
"spikethickness": 1,
"spikecolor": "rgba(48, 105, 152, 0.3)",
"spikedash": "dot",
},
yaxis={
"title": {"text": "Density", "font": {"size": 28}},
"tickfont": {"size": 22},
"showgrid": True,
"gridcolor": "rgba(128, 128, 128, 0.15)",
"gridwidth": 1,
"gridcolor": "rgba(128, 128, 128, 0.2)",
"zeroline": False,
"rangemode": "tozero",
},
template="plotly_white",
showlegend=True,
legend={
"font": {"size": 20},
"x": 0.98,
"y": 0.98,
"x": 0.97,
"y": 0.95,
"xanchor": "right",
"yanchor": "top",
"bgcolor": "rgba(255, 255, 255, 0.8)",
"borderwidth": 0,
},
margin={"l": 100, "r": 60, "t": 100, "b": 100},
hovermode="x",
margin={"l": 90, "r": 40, "t": 90, "b": 90},
plot_bgcolor="white",
)

# Save as PNG and HTML
# Save
fig.write_image("plot.png", width=1600, height=900, scale=3)
fig.write_html("plot.html", include_plotlyjs="cdn")
fig.write_html("plot.html", include_plotlyjs="cdn", config={"displayModeBar": True, "scrollZoom": True})
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