Saving Figures¶

Exporting figures to files is essential for reports, papers, and presentations.

Basic savefig¶

Save using the Figure object:

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(0, 2*np.pi, 100)
y = np.sin(x)

fig, ax = plt.subplots()
ax.plot(x, y)

fig.savefig("sine_wave.png")

Or via pyplot:

plt.savefig("sine_wave.png")

File Formats¶

Common formats and their use cases:

Format	Type	Best For
PNG	Raster	Screen display, presentations
PDF	Vector	Papers, high-quality print
SVG	Vector	Web, scalable graphics
EPS	Vector	LaTeX documents
JPEG	Raster	Photos (lossy compression)

fig.savefig("plot.png")
fig.savefig("plot.pdf")
fig.savefig("plot.svg")

Resolution (DPI)¶

Control resolution with the dpi parameter:

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(-2, 2, 1000)
y1 = np.cos(40 * x)
y2 = np.exp(-x**2)

fig = plt.figure(figsize=(8, 2.5), facecolor="#f1f1f1")
ax = fig.add_axes((0.1, 0.1, 0.8, 0.8), facecolor="#e1e1e1")

ax.plot(x, y1 * y2)
ax.plot(x, y2, 'g')
ax.set_xlabel("x")
ax.set_ylabel("y")

# Higher DPI = larger file, better quality
fig.savefig("graph_lowres.png", dpi=72)
fig.savefig("graph_highres.png", dpi=300)

DPI guidelines:

Screen: 72-100 dpi
Print: 300 dpi
Publication: 300-600 dpi

Background Options¶

Control background appearance:

# White background (default)
fig.savefig("plot.png")

# Custom background color
fig.savefig("plot.png", facecolor="#f1f1f1")

# Transparent background
fig.savefig("plot.png", transparent=True)

# Edge color
fig.savefig("plot.png", edgecolor='black')

Bounding Box¶

Control what portion of the figure is saved:

# Tight bounding box (removes whitespace)
fig.savefig("plot.png", bbox_inches='tight')

# Add padding around tight box
fig.savefig("plot.png", bbox_inches='tight', pad_inches=0.1)

Complete Example¶

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(-2*np.pi, 2*np.pi, 100)
y_sin = np.sin(x)
y_cos = np.cos(x)

fig, ax = plt.subplots(figsize=(10, 4))
ax.plot(x, y_sin, label='sin(x)')
ax.plot(x, y_cos, label='cos(x)')
ax.set_xlabel('x')
ax.set_ylabel('y')
ax.set_title('Trigonometric Functions')
ax.legend()
ax.grid(True, alpha=0.3)

# Save with all options
fig.savefig(
    "trig_functions.png",
    dpi=300,
    bbox_inches='tight',
    pad_inches=0.1,
    facecolor='white',
    transparent=False
)

plt.show()

Saving Multiple Formats¶

Save the same figure in multiple formats:

import matplotlib.pyplot as plt
import numpy as np

fig, ax = plt.subplots()
ax.plot([1, 2, 3, 4])

for fmt in ['png', 'pdf', 'svg']:
    fig.savefig(f"output.{fmt}", dpi=300, bbox_inches='tight')

Best Practices¶

Use vector formats for print: PDF or SVG scale without quality loss
Use PNG for web/screen: Good quality, universal support
Set DPI before plotting: fig = plt.figure(dpi=300)
Use bbox_inches='tight': Removes unwanted whitespace
Be consistent: Use the same settings across all figures in a document

Key Takeaways¶

Use fig.savefig() to export figures
Choose format based on use case (PNG for screen, PDF for print)
Higher DPI means better quality but larger files
Use bbox_inches='tight' to remove whitespace
Use transparent=True for overlay graphics