How Can I Normalize Unicode Strings in Python to Simplify Composite Characters?

Normalizing Unicode

Unicode strings often contain composite characters that are represented as a sequence of two or more code points. These composites can sometimes be normalized into simpler, single-code-point entities.

Problem

The unicodedata module provides a convenient way to access Unicode character information. However, manually iterating over characters and replacing composites with their non-composite equivalents can be inefficient and error-prone.

Solution

To normalize a Unicode string and convert composites to their simplest form, use the unicodedata.normalize() function with the 'NFC' (Normal Form Composed) option. This form replaces composite characters with their precomposed counterparts.

For example:

>>> import unicodedata
>>> char = "á"
>>> unicodedata.normalize('NFC', char) == "á"
True

Conversely, the 'NFD' (Normal Form Decomposed) option converts precomposed characters into their decomposed form:

>>> char = "á"
>>> unicodedata.normalize('NFD', char) == "a\u0301"
True

Additional Normalization Forms

In addition to NFC and NFD, there are two additional normalization forms:

• NFKC: Compatible Normal Form Composed, which also replaces compatibility characters with their canonical form.
• NFKD: Compatible Normal Form Decomposed, which combines NFKD and removes compatibility characters.

Example:

>>> char = "Ⅷ"
>>> unicodedata.normalize('NFKC', char) == "VIII"
True

Note: Normalization is not always reversible; decomposing a character to NFD and then recomposing it to NFC may not always result in the original character sequence.

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