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Generate unoccupied name.

Project description


Find an unoccupied name from basename & occupied names.

If you tired to write a bunch of code to deal unnamed note 02, pic-03.jpg, naming problem. It's for you.


  • Based on basename: find an unoccupied name as close as user wanted, not randomly.
  • Isolated: pure function API, no related outer environment like filesystem or DB.
  • Stable: consider edge situations and already be tested.
  • Flexible: library user can choice / overwrite naming algorithm easily.


Basic Usage

Use basename and occupied container (an iterable) to find a unoccupied name:

from unoccupied import unoccupied

basename = 'foo'

unoccupied(basename, [])  # 'foo' not be occupied
# >>> 'foo'

unoccupied(basename, ['foo'])  # 'foo' already be occupied
# >>> 'foo-1'

unoccupied(basename, ['foo', 'foo-1'])  # 'foo' & 'foo-1' already be occupied
# >>> 'foo-2'

Name Finder

Name finder offer an algorithm to find (or generate) an unoccupied name.

Let's try to change the default name finder:

from unoccupied import unoccupied
from unoccupied import NumberNameFinder  # A built-in name finder generator

# test data
basename = 'foo'
occupied = ['foo', 'bar', 'foo-1']

unoccupied(basename, occupied)  # use defualt name finder
# >>> 'foo-2'

name_finder = NumberNameFinder(template='{basename}-{num:02}')  # <- look here
unoccupied(basename, occupied, name_finder)
# >>> 'foo-01'

Another case: Assume we need to find an unoccupied filename, but, we don't want the base filename foo.txt become foo.txt-1. The foo-1.txt is much suitable name. Try the built-in FileNameFinder().

from unoccupied import unoccupied
from unoccupied import FileNameFinder  # here

# test data
basename = 'pic.jpg'
occupied = ['pic.jpg', 'pic-1.jpg', 'foo']  # may use os.listdir() in real case

unoccupied(basename, occupied, FileNameFinder())  # <- look here
# >>> 'pic-2.jpg'

name_finder = FileNameFinder(template='{base}.{num:02}', start=0)
unoccupied(basename, occupied, name_finder)
# >>> 'pic.00.jpg'

Build a Name Finder

A name_finder is just a callable accept 2 arguments: (basename, norm_occupied), so feel free to build your own. e.g.:

import string
from unoccupied import unoccupied

def alphabet_name_finder(basename, norm_occupied):
    for char in string.ascii_lowercase:
        testing_name = '{}-{}'.format(basename, char)
        if testing_name not in norm_occupied:
            return testing_name

unoccupied('foo', ['foo'], alphabet_name_finder)
# >>> 'foo-a'

Or, using BaseNameFinder class to build a name_finder:

import string
from unoccupied import unoccupied
from unoccupied import BaseNameFinder

class AlphabetNameFinder(BaseNameFinder):
    """Basic alphabet name finder."""
    def ids_generator(self):
        return string.ascii_lowercase

alphabet_name_finder = AlphabetNameFinder()

unoccupied('foo', ['foo'], alphabet_name_finder)
# >>> 'foo-a'

class AlphabetNameFinder2(BaseNameFinder):
    """Configurable alphabet name finder."""
    def __init__(self, template):       # here is a configurable option.
        self.template = template

    def ids_generator(self):
        return string.ascii_lowercase

    def formatter(self, basename, id):  # change formatting algorithm
        return self.template.format(basename=basename, id=id)

alphabet_name_finder2 = AlphabetNameFinder2(template='{basename}.{id}')

unoccupied('foo', ['foo'], alphabet_name_finder2)
# >>> 'foo.a'

As you see. BaseNameFinder packed some tedious work like for-loop & infinite loop checking. And good for offer some configurable options for further usage.


function unoccupied(basename, occupied, name_finder=NumberNameFinder(), skipbase=False)

Find a unoccupied name.

  • basename: (str) the wanted basename.
  • occupied: (str of iterable) the names already be occupied.

name_finder is a callable with 2 arguments (basename, norm_occupied). This function only be called when basename cannot use directly, and it should return None or string. Return None mean it can't find any unoccupied name and cause unoccupied() raise UnoccupiedNameNotFound exception.

Hint: occupied will be convert to frozenset data type (we call it norm_occupied) and inject to name_finder. If and only if you try to build a name_finder by yourself, you may need to know that.

skipbase is a boolean value. If True, basename will not return directly, no matter the basename already in occupied or not. So user can generate a consistent name series like pic-01, pic-02 and without pic.

class BaseNameFinder()

This is the base class of built-in NameFinder class. It has 2 method which can (but not necessary) be overwrited:

method ids_generator(self) -> Iterable

This method will create a series of id and push into self.formatter().

method formatter(self, basename, id) -> str

This method can assemble basename and id then return a string by any algorithm.

class NumberNameFinder(template='{basename}-{num}', start=1)

Generate a name_finder to find an unoccupied name with basename and an increasing number.

The template argument is a python str.format() template. This template can include 2 keyword params. {basename} represent the original basename. {num} represent an increasing number.

start argument can define what {num} starts from.

class FileNameFinder(template='{base}-{num}', start=1)

Generate a name_finder to find an unoccupied name with processed filename and an increasing number.

The template argument is a python str.format() template. This template can include 2 keyword params. {base} represent the filename without extension. {num} represent an increasing number. Hint: the filename extension will be appended automatically.

start argument can define what {num} starts from.


./ test  # or pytest


pip install unoccupied

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