The strrange is a Python library that helps produce sequences of strings given the first and last element. It is designed to cover common practical cases like file names, numeric identifiers, and alphanumeric codes.

Table of contents#

Installation#

Requires Python version 3.10 or higher. To install the package, run:

pip install strrange

Example#

from strrange import range as srange

print(list('AA' + srange('QM', 'QZ') + srange('XA', 'XZ') + 'ZZ'))
# Output: list of ISO 3166-1 alpha-2 codes for private use, total 42 items.

Description#

The main function is strrange.range(start: str, stop: str), which generates strings from start to stop, inclusive.

  • The function attempts to “guess” the progression by analyzing numeric parts, repeated substrings, and alphanumeric regions (0–9 A–Z a–z).
  • If start and stop share a common prefix or suffix, it is preserved where possible.
  • If an integer is detected in the pattern, and it begins with 0 or a space, the generated numbers are padded accordingly.
  • If stop is less than start (in some alphabet or as numbers), the sequence is generated in reverse (from stop to start).
  • If both start and stop are empty strings, the result is an empty sequence.
  • If start and stop are equal, the result contains exactly one element.
  • If no obvious pattern is found, it simply yields [start, stop].

The padding style is determined by the start string only:

list(srange('img001.png', 'img5.png'))
# ['img001.png', 'img002.png', 'img003.png', 'img004.png', 'img005.png']

Signs and underscores in numeric literals are recognized, but may be ignored in the output:

list(srange('1_000.png', '+1002.png'))
# ['1000.png', '1001.png', '1002.png']

Ambiguities are inevitable: the algorithm is “magical” in the sense that it tries to guess the intended sequence, but sometimes this magic does not work. For example, after the sequence 'A8', 'A9' should the next element be 'AA', 'A10', 'BA', or 'B0'?

For fine-grained control, you may use the underlying Alphabet class.

Actually, strrange.range returns not a plain generator, but a special range object that is iterable and also supports concatenation with:

  • Other strrange.range objects
  • Lists of strings
  • Single strings (treated as scalar values, not iterables)

This allows you to build composite sequences easily.

The development status is alpha; algorithms are heuristic and may change. If you encounter results that seem unexpected, please share examples — even if they won’t always lead to changes (what is unexpected for one user may be the intended logic for another), they help us understand real-world cases.

Examples are welcome as issue reports or pull requests.