MeCab Python 3 Wrapper

Warnings

• breaking Python 2 support was officially dropped in version 1.0.3. Users on Python 2 must use an older version.
  Fix: Upgrade to Python 3.x and mecab-python3 version 1.0.3 or higher.
• breaking The bundled IPAdic dictionary was removed in version 1.0.0 (first released as 1.0.0a1). This means MeCab will now rely on system-installed dictionaries or those installed via Python packages like `unidic-lite`.
  Fix: Explicitly install a dictionary package like `unidic-lite` (`pip install unidic-lite`) or ensure a system-wide MeCab dictionary is available and configured.
• gotcha MeCab requires a dictionary to perform analysis. While `mecab-python3` installs the Python wrapper, a dictionary like `unidic-lite` or `unidic` must be installed separately (e.g., `pip install unidic-lite`) or by using the `mecab-python3[unidic-lite]` extra. Without a dictionary, `MeCab.Tagger()` will fail with a `RuntimeError`.
  Fix: Install a dictionary package: `pip install unidic-lite`. If specifying a custom dictionary path, ensure a valid `mecabrc` file is also present.
• gotcha On Windows, a Microsoft Visual C++ Redistributable is required for `mecab-python3` wheels to function correctly. This is a common oversight leading to runtime errors.
  Fix: Download and install the appropriate Microsoft Visual C++ Redistributable for your system (e.g., from Microsoft's website).
• gotcha Since version 1.0.4, errors during MeCab initialization (e.g., missing dictionary) now consistently throw a `RuntimeError` instead of printing messages directly to `stdout`. This is an improvement but could affect scripts that parsed `stdout` for error detection.
  Fix: Update error handling logic to catch `RuntimeError` for initialization failures. The error message provides guidance.
• gotcha The `MeCab.VERSION` attribute (if accessed) refers to the version of the underlying MeCab C++ library (typically 0.996), not the `mecab-python3` Python package version. It has not changed for many years and is not generally useful for tracking the Python wrapper's version.
  Fix: Refer to `mecab-python3.__version__` or PyPI for the Python package version. Avoid relying on `MeCab.VERSION`.

Install

• pip install mecab-python3 Basic Installation
• pip install mecab-python3[unidic-lite] With UniDic-lite dictionary (recommended)
• pip install unidic-lite Install UniDic-lite separately

Imports

• MeCab

  import MeCab

  The module name is capitalized 'MeCab', not 'mecab'. Common ImportError due to incorrect capitalization.

Quickstart

This quickstart demonstrates basic morphological analysis using MeCab, including word segmentation ('wakati-gaki') and detailed analysis. It highlights the necessity of a dictionary for operation and includes basic error handling for common setup issues.

import MeCab
import os

# The library needs a dictionary to function. unidic-lite is recommended.
# Ensure it's installed: pip install unidic-lite

try:
    # Initialize Tagger for 'wakati-gaki' (word segmentation)
    wakati = MeCab.Tagger('-Owakati')
    text_wakati = wakati.parse('すもももももももものうち')
    print(f"Wakati-gaki: {text_wakati.strip().split()}")

    # Initialize Tagger for detailed analysis (default)
    tagger = MeCab.Tagger('') # An empty string often defaults to system mecabrc or attempts autodetection
    text_full = tagger.parse('これは日本語の形態素解析のテストです。')
    print(f"\nDetailed Analysis:\n{text_full}")

except RuntimeError as e:
    print(f"MeCab initialization failed: {e}")
    print("Please ensure a dictionary (e.g., unidic-lite) is installed and correctly configured.")
    print("On Windows, you may also need the Microsoft Visual C++ Redistributable.")
except ImportError as e:
    print(f"Missing dictionary package: {e}")
    print("Please install a dictionary, e.g., 'pip install unidic-lite'")