The same plot in 14 other libraries — Python: Altair, Bokeh, lets-plot, Matplotlib, Plotly, plotnine, Seaborn; R: ggplot2; Julia: Makie.jl; JavaScript: Chart.js, D3.js, Apache ECharts, Highcharts, MUI X Charts. Compare all 15 side by side: NMR Spectrum (Nuclear Magnetic Resonance) in Python, R, Julia and JavaScript.
An NMR spectrum plots signal intensity versus chemical shift (in ppm) to reveal the electronic environment of atomic nuclei in a molecule. It is the primary analytical tool in organic chemistry for determining molecular structure, with peak positions indicating functional groups and splitting patterns (multiplets) revealing connectivity between neighboring atoms. The x-axis is conventionally reversed (high ppm on the left) and peaks appear as sharp signals rising from a baseline.
""" anyplot.ai
spectrum-nmr: NMR Spectrum (Nuclear Magnetic Resonance)
Library: pygal 3.1.0 | Python 3.13.13
Quality: 87/100 | Updated: 2026-06-03
"""
import os
import numpy as np
import pygal
from pygal.style import Style
# Theme tokens — Imprint palette, theme-adaptive chrome
THEME = os.getenv("ANYPLOT_THEME", "light")
PAGE_BG = "#FAF8F1" if THEME == "light" else "#1A1A17"
INK = "#1A1A17" if THEME == "light" else "#F0EFE8"
INK_MUTED = "#6B6A63" if THEME == "light" else "#A8A79F"
# Imprint palette — hybrid-v3 sort; position 1 (#009E73) always first series
IMPRINT_PALETTE = ("#009E73", "#C475FD", "#4467A3", "#BD8233", "#AE3030", "#2ABCCD", "#954477", "#99B314")
# Data: Synthetic 1H NMR spectrum of ethanol (CH3-CH2-OH)
np.random.seed(42)
chemical_shift = np.linspace(0, 12, 6000)
w = 0.010 # Lorentzian half-width for multiplet peaks
# Build spectrum with Lorentzian line shapes: h·w²/((x−c)²+w²)
intensity = np.zeros_like(chemical_shift)
# TMS reference peak at 0 ppm (singlet)
intensity += 0.30 * 0.008**2 / ((chemical_shift - 0.00) ** 2 + 0.008**2)
# CH3 triplet near 1.18 ppm (1:2:1 intensity pattern, J = 7 Hz)
tc, j = 1.18, 0.07
intensity += 0.50 * w**2 / ((chemical_shift - (tc - j)) ** 2 + w**2)
intensity += 1.00 * w**2 / ((chemical_shift - tc) ** 2 + w**2)
intensity += 0.50 * w**2 / ((chemical_shift - (tc + j)) ** 2 + w**2)
# CH2 quartet near 3.69 ppm (1:3:3:1 intensity pattern, J = 7 Hz)
qc = 3.69
intensity += 0.25 * w**2 / ((chemical_shift - (qc - 1.5 * j)) ** 2 + w**2)
intensity += 0.75 * w**2 / ((chemical_shift - (qc - 0.5 * j)) ** 2 + w**2)
intensity += 0.75 * w**2 / ((chemical_shift - (qc + 0.5 * j)) ** 2 + w**2)
intensity += 0.25 * w**2 / ((chemical_shift - (qc + 1.5 * j)) ** 2 + w**2)
# OH singlet near 2.61 ppm
intensity += 0.35 * 0.015**2 / ((chemical_shift - 2.61) ** 2 + 0.015**2)
# Subtle baseline noise
intensity += np.random.normal(0, 0.003, len(chemical_shift))
intensity = np.clip(intensity, 0, None)
# Downsample for pygal performance (every 6th point → ~1000 points)
cs_plot = chemical_shift[::6]
int_plot = intensity[::6]
# Negate x-values to reverse axis (NMR convention: high ppm on left)
cs_negated = -cs_plot
# Peak annotations with functional group labels
peak_info = [(0.00, "TMS"), (1.18, "CH₃ triplet"), (2.61, "OH singlet"), (3.69, "CH₂ quartet")]
# Style — Imprint palette, theme-adaptive chrome, canonical 3200×1800 sizing
custom_style = Style(
background=PAGE_BG,
plot_background=PAGE_BG,
foreground=INK,
foreground_strong=INK,
foreground_subtle=INK_MUTED,
colors=IMPRINT_PALETTE,
title_font_size=66,
label_font_size=56,
major_label_font_size=44,
legend_font_size=44,
value_font_size=40,
stroke_width=2.5,
)
# Chart — 3200×1800 landscape (canonical canvas for native-pixel pygal)
title = "Ethanol ¹H NMR · spectrum-nmr · python · pygal · anyplot.ai"
chart = pygal.XY(
style=custom_style,
width=3200,
height=1800,
title=title,
x_title="Chemical Shift (ppm)",
y_title="Intensity (a.u.)",
show_dots=False,
print_labels=True,
print_values=False,
show_x_guides=False,
show_y_guides=True,
show_legend=False,
xrange=(-12.5, 0.8),
range=(-0.02, 1.12),
margin=35,
margin_top=60,
margin_bottom=80,
margin_left=75,
margin_right=300,
tooltip_fancy_mode=True,
tooltip_border_radius=8,
x_value_formatter=lambda x: f"{abs(x):.1f}",
y_value_formatter=lambda y: f"{y:.3f}",
x_labels_major_every=2,
css=[
"file://style.css",
"file://graph.css",
"inline:.axis > .line { stroke: transparent !important; }",
"inline:.chart-background { rx: 0; ry: 0; }",
f"inline:.text-overlay .series .label {{ font-size: 38px !important; fill: {INK} !important; font-weight: bold !important; }}",
],
)
# Spectrum line — stroke_style width=4 for crisp visibility at 3200×1800
spectrum_points = [(float(cs), float(inten)) for cs, inten in zip(cs_negated, int_plot, strict=False)]
chart.add("¹H NMR Spectrum", spectrum_points, stroke_style={"width": 4}, fill=False)
# Peak markers — search in downsampled arrays so dots snap to spectrum line
for ppm, group_name in peak_info:
mask = np.abs(cs_plot - ppm) < 0.15
region_idx = np.where(mask)[0]
idx = int(region_idx[np.argmax(int_plot[region_idx])])
peak_x = -float(cs_plot[idx])
peak_y = float(int_plot[idx])
label_text = f"{group_name} ({ppm:.2f} ppm)"
legend_label = f"{group_name} ({ppm:.1f})"
point = {"value": (peak_x, peak_y), "label": label_text}
chart.add(legend_label, [point], stroke=False, show_dots=True, dots_size=14)
# Save PNG and interactive HTML
chart.render_to_png(f"plot-{THEME}.png")
with open(f"plot-{THEME}.html", "wb") as f:
f.write(chart.render())
Runnable source as JSON, for any HTTP client: https://api.anyplot.ai/specs/spectrum-nmr/pygal/code. Any spec id and library id listed in llms-full.txt fit the same URL shape; every URL below is complete and callable.
{
"spec_id": "spectrum-nmr",
"language": "python",
"library": "pygal",
"page": "https://anyplot.ai/spectrum-nmr/python/pygal",
"hub": "https://anyplot.ai/spectrum-nmr",
"code_json": "https://api.anyplot.ai/specs/spectrum-nmr/pygal/code",
"spec_json": "https://api.anyplot.ai/specs/spectrum-nmr",
"render_light_png": "https://storage.googleapis.com/anyplot-images/plots/spectrum-nmr/python/pygal/plot-light.png",
"render_dark_png": "https://storage.googleapis.com/anyplot-images/plots/spectrum-nmr/python/pygal/plot-dark.png",
"interactive_light_html": "https://storage.googleapis.com/anyplot-images/plots/spectrum-nmr/python/pygal/plot-light.html",
"interactive_dark_html": "https://storage.googleapis.com/anyplot-images/plots/spectrum-nmr/python/pygal/plot-dark.html",
"quality_score": 87.0,
"license": "MIT",
"guide": "https://anyplot.ai/llms.txt"
}Part of NMR Spectrum (Nuclear Magnetic Resonance) on anyplot.ai.