Physics Visualization

Overview

Generate publication-quality figures for physics: vector fields, streamlines, contour plots, 3D surfaces, phase diagrams, spectrograms, and animations. All plots use LaTeX rendering, proper colormaps, and journal-ready formatting.

When to Use

• Any physics result that needs a figure
• Vector fields (E&M, fluid flow, gravitational fields)
• Contour/heatmap plots (potential fields, temperature distributions, wavefunctions)
• Phase space plots (trajectories, Poincare sections)
• 3D surface plots (energy landscapes, wavefunctions)
• Animations (time-evolving systems)
• Multi-panel comparison figures

Setup

import numpy as np
import matplotlib
matplotlib.use('Agg')  # non-interactive backend for scripts
import matplotlib.pyplot as plt
from matplotlib import cm
from mpl_toolkits.mplot3d import Axes3D

# Publication-quality defaults
plt.rcParams.update({
    'font.size': 12,
    'axes.labelsize': 14,
    'axes.titlesize': 15,
    'xtick.labelsize': 11,
    'ytick.labelsize': 11,
    'legend.fontsize': 11,
    'figure.dpi': 150,
    'savefig.dpi': 300,
    'savefig.bbox': 'tight',
    'axes.grid': True,
    'grid.alpha': 0.3,
    'lines.linewidth': 1.5,
})

# Enable LaTeX if available
try:
    plt.rcParams.update({
        'text.usetex': True,
        'font.family': 'serif',
    })
except:
    pass  # fallback to mathtext

Core Plot Types

1. Vector Field

def plot_vector_field(ax, X, Y, U, V, title='', normalize=True, cmap='viridis'):
    """Plot a 2D vector field with magnitude coloring."""
    magnitude = np.sqrt(U**2 + V**2)
    if normalize:
        U_n = U / (magnitude + 1e-10)
        V_n = V / (magnitude + 1e-10)
    else:
        U_n, V_n = U, V

    q = ax.quiver(X, Y, U_n, V_n, magnitude, cmap=cmap, alpha=0.8)
    plt.colorbar(q, ax=ax, label='|F|')
    ax.set_title(title)
    ax.set_aspect('equal')
    return q

# Example: Electric dipole field
x = np.linspace(-3, 3, 20)
y = np.linspace(-3, 3, 20)
X, Y = np.meshgrid(x, y)

# Dipole at (±0.5, 0)
def dipole_field(X, Y, d=0.5):
    r_plus = np.sqrt((X-d)**2 + Y**2)
    r_minus = np.sqrt((X+d)**2 + Y**2)
    Ex = (X-d)/r_plus**3 - (X+d)/r_minus**3
    Ey = Y/r_plus**3 - Y/r_minus**3
    return Ex, Ey

Ex, Ey = dipole_field(X, Y)
fig, ax = plt.subplots(figsize=(8, 8))
plot_vector_field(ax, X, Y, Ex, Ey, title='Electric Dipole Field')
ax.set_xlabel('x [m]')
ax.set_ylabel('y [m]')
plt.savefig('vector_field.png', dpi=150, bbox_inches='tight')

2. Streamlines

fig, ax = plt.subplots(figsize=(10, 8))
x_fine = np.linspace(-3, 3, 100)
y_fine = np.linspace(-3, 3, 100)
X_f, Y_f = np.meshgrid(x_fine, y_fine)
Ex_f, Ey_f = dipole_field(X_f, Y_f)
magnitude = np.sqrt(Ex_f**2 + Ey_f**2)

strm = ax.streamplot(X_f, Y_f, Ex_f, Ey_f, color=np.log10(magnitude+1e-3),
                      cmap='inferno', density=2, linewidth=1, arrowsize=1.5)
plt.colorbar(strm.lines, ax=ax, label=r'$\log_{10}|E|$')
ax.plot([-0.5, 0.5], [0, 0], 'ro', markersize=10, label='Charges')
ax.set_xlabel('x [m]')
ax.set_ylabel('y [m]')
ax.set_title('Electric Field Streamlines')
ax.legend()
plt.savefig('streamlines.png', dpi=150, bbox_inches='tight')

3. Contour / Heatmap

def plot_contour(ax, X, Y, Z, title='', levels=20, cmap='RdBu_r', symmetric=True):
    """Contour plot with optional symmetric colorbar (good for potentials)."""
    if symmetric:
        vmax = np.max(np.abs(Z))
        vmin = -vmax
    else:
        vmin, vmax = Z.min(), Z.max()

    cf = ax.contourf(X, Y, Z, levels=levels, cmap=cmap, vmin=vmin, vmax=vmax)
    cs = ax.contour(X, Y, Z, levels=levels, colors='k', linewidths=0.3, alpha=0.5)
    plt.colorbar(cf, ax=ax, label=title)
    ax.clabel(cs, inline=True, fontsize=8, fmt='%.1f')
    ax.set_aspect('equal')
    return cf

# Example: 2D wavefunction |ψ|²
r = np.linspace(-5, 5, 200)
X, Y = np.meshgrid(r, r)
R = np.sqrt(X**2 + Y**2)
# Hydrogen 2p orbital (simplified)
psi = R * np.exp(-R/2) * X / R  # p_x orbital
psi_sq = np.abs(psi)**2

fig, ax = plt.subplots(figsize=(8, 7))
plot_contour(ax, X, Y, psi_sq, title=r'$|\psi_{2p}|^2$', symmetric=False, cmap='hot')
ax.set_xlabel('x [a₀]')
ax.set_ylabel('y [a₀]')
ax.set_title(r'Hydrogen $2p_x$ Probability Density')
plt.savefig('wavefunction.png', dpi=150, bbox_inches='tight')

4. 3D Surface

fig = plt.figure(figsize=(10, 8))
ax = fig.add_subplot(111, projection='3d')

# Energy landscape
x = np.linspace(-2, 2, 100)
y = np.linspace(-2, 2, 100)
X, Y = np.meshgrid(x, y)
Z = (X**2 - 1)**2 + Y**2  # double-well potential

surf = ax.plot_surface(X, Y, Z, cmap='coolwarm', alpha=0.8,
                       linewidth=0, antialiased=True)
ax.set_xlabel('x')
ax.set_ylabel('y')
ax.set_zlabel('V(x,y)')
ax.set_title('Double-Well Potential')
fig.colorbar(surf, ax=ax, shrink=0.6, label='V')
plt.savefig('surface_3d.png', dpi=150, bbox_inches='tight')

5. Animation

from matplotlib.animation import FuncAnimation, PillowWriter

def create_animation(update_func, n_frames, fig, interval=50, filename='animation.gif'):
    """Create and save an animation."""
    anim = FuncAnimation(fig, update_func, frames=n_frames, interval=interval, blit=True)
    writer = PillowWriter(fps=1000/interval)
    anim.save(filename, writer=writer)
    print(f"Animation saved: {filename}")
    return anim

# Example: wave propagation
fig, ax = plt.subplots(figsize=(10, 4))
x = np.linspace(0, 10, 500)
line, = ax.plot(x, np.sin(x), 'b-', linewidth=2)
ax.set_ylim(-1.5, 1.5)
ax.set_xlabel('x')
ax.set_ylabel('u(x,t)')
time_text = ax.text(0.02, 0.95, '', transform=ax.transAxes)

def update(frame):
    t = frame * 0.05
    y = np.sin(2*np.pi*(x - t)) * np.exp(-0.1*t)
    line.set_ydata(y)
    time_text.set_text(f't = {t:.2f}')
    return line, time_text

create_animation(update, 200, fig, interval=33, filename='wave.gif')

6. Multi-Panel Figure

def multi_panel(n_rows, n_cols, figsize=None, sharex=False, sharey=False):
    """Create a multi-panel figure with consistent styling."""
    if figsize is None:
        figsize = (5*n_cols, 4*n_rows)
    fig, axes = plt.subplots(n_rows, n_cols, figsize=figsize,
                              sharex=sharex, sharey=sharey)
    # Add panel labels (a), (b), (c), ...
    if n_rows * n_cols > 1:
        for i, ax in enumerate(np.atleast_1d(axes).flat):
            label = chr(ord('a') + i)
            ax.text(-0.12, 1.05, f'({label})', transform=ax.transAxes,
                    fontsize=14, fontweight='bold', va='top')
    return fig, axes

Colormap Guide

Data Type	Recommended Colormap	Why
Sequential (magnitude, density)	viridis, plasma, inferno	Perceptually uniform, colorblind-safe
Diverging (potential, temperature anomaly)	RdBu_r, coolwarm	Symmetric around zero
Cyclic (phase, angle)	twilight, hsv	Wraps around
Binary (positive/negative)	bwr	Clear sign distinction

Never use jet or rainbow — they are not perceptually uniform and mislead.

Save Format Guide

Format	When to Use
PNG (300 dpi)	General use, presentations
PDF	Journal submission, vector graphics
SVG	Web, editable vector
EPS	Legacy journals requiring EPS

Always save both PNG and PDF:

plt.savefig('figure.png', dpi=300, bbox_inches='tight')
plt.savefig('figure.pdf', bbox_inches='tight')