svgpathtools

Common errors

• could not convert string to float: 's'

  cause This error, or similar ones like 'list index out of range', often occurs when `svgpathtools.parse_path()` attempts to parse an SVG path `d` attribute string that is malformed or contains unexpected characters/commands. This can happen with complex SVG exports from graphic design software (e.g., Inkscape) that might use non-standard or subtly incorrect syntax for path commands.
  fix Validate the SVG `d` string against the official SVG Path Data specification. Simplify the path in the originating software, or manually inspect and correct the `d` attribute string. Ensure all path commands (M, L, C, A, Z, etc.) are correctly capitalized (for absolute coordinates) or lowercase (for relative coordinates) and have the correct number of parameters.

• SVG groups are ignored. Especially transformations acting on the paths inside the group.

  cause The `svg2paths()` function processes path elements directly and does not automatically apply transformations defined on parent `<g>` (group) elements in the SVG document structure.
  fix After reading the paths using `svg2paths()`, you need to manually traverse the SVG's DOM (e.g., using `xml.etree.ElementTree`) to identify parent group transformations and apply them to the respective child paths. The `Document` class (experimental) aims to provide a higher-level API that might simplify this in the future.

Warnings

• gotcha The `svg2paths()` function currently ignores SVG group (<g>) transformations when parsing files. Paths inside groups will be read without the parent group's transformations applied.
  Fix: Manually apply transformations to paths after reading, or use the experimental `Document` class for improved I/O which might handle transformations better (check its documentation). See GitHub issue #16 for discussion and manual transformation examples.
• gotcha Some functionality within `svgpathtools`, particularly concerning discontinuous `Path` objects, has not been fully tested and might lead to unexpected behavior.
  Fix: For potentially discontinuous paths, consider using the `Path.continuous_subpaths()` method to break them into continuous components as a workaround.
• gotcha The `Path.scaled()` method might produce visual artifacts or unexpected 'cavities' in paths when using very small scaling factors (e.g., below ~0.45). This could be due to internal segmentation or precision issues.
  Fix: If encountering issues with small scaling factors, consider applying scaling to individual path segment parameters or control points manually, or scaling the SVG in a graphics editor before processing.
• deprecated The `svg2paths` function's argument signature in older installed versions (e.g., via `pip3`) might not perfectly match the latest documentation or GitHub source, particularly regarding `convert_circles_to_paths` and `convert_ellipses_to_paths` arguments.
  Fix: Ensure you are using the latest version of `svgpathtools`. If discrepancies persist, consider installing directly from the GitHub source if comfortable, or check the `svg_to_paths.py` source file for the exact function signature on your installed version.

Install

• pip install svgpathtools Install stable version

Imports

• Path

  from svgpathtools import Path

  Main class for composite paths.
• Line, QuadraticBezier, CubicBezier, Arc

  from svgpathtools import Line, QuadraticBezier, CubicBezier, Arc

  Classes for individual path segments.
• svg2paths

  from svgpathtools import svg2paths

  Function to read paths from an SVG file.
• wsvg

  from svgpathtools import wsvg

  Function to write paths to an SVG file.
• Path
  wrong:

  from svg.path import Path

  correct:

  from svgpathtools import Path

  While `svgpathtools` was inspired by `svg.path`, its classes and functions are part of the `svgpathtools` namespace. Direct imports from `svg.path` will result in different objects and methods.

Quickstart

This quickstart demonstrates how to read paths from an SVG file, modify an existing path (e.g., scaling it), create a new path using segment classes (Line, CubicBezier), and then write all paths to a new SVG file. Coordinates are handled as complex numbers (x + yj).

from svgpathtools import svg2paths, wsvg, Path, Line, CubicBezier
import os

# Create a dummy SVG file for demonstration
with open('example.svg', 'w') as f:
    f.write('<svg width="200" height="200">')
    f.write('<path d="M10 10 L100 10 L100 100 L10 100 Z" fill="blue"/>')
    f.write('</svg>')

# 1. Read paths from an existing SVG file
paths, attributes = svg2paths('example.svg')
print(f"Read {len(paths)} path(s) from example.svg")

# 2. Manipulate a path (e.g., scale the first path)
if paths:
    original_path = paths[0]
    # Scale the path by 0.5
    scaled_path = original_path.scaled(0.5)
    paths[0] = scaled_path
    print(f"Scaled the first path. New length: {scaled_path.length():.2f}")

# 3. Create a new path programmatically
new_segment1 = Line(start=10+10j, end=50+100j)
new_segment2 = CubicBezier(start=50+100j, control1=150+50j, control2=50+150j, end=150+100j)
new_path = Path(new_segment1, new_segment2)

# Add the new path to the list and assign attributes
paths.append(new_path)
attributes.append({'fill': 'red', 'stroke': 'black', 'stroke-width': '2'})

# 4. Write the modified and new paths to a new SVG file
wsvg(paths, attributes=attributes, filename='output.svg', openinbrowser=False)
print("Modified paths written to output.svg")

# Clean up dummy file (optional)
os.remove('example.svg')
# os.remove('output.svg') # Uncomment to remove output file after inspection