rangeslicetools.py

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This is a library to manipulate python range and slice objects. The objects of these classes have the same internal structure but a bit different semantics and set of available methods. Unfortunately these objects include no methods to manipulate them and unfortunately they cannot be subclassed.

So I have implemented a set of functions to manipulate these objects. Their names follow the following conventions:

• All these functions names begin from s which stands there for slice, even though they will work for ranges too.

• If a name ends with _, it is a generator, otherwise it returns a list.

WARNING: FOR NEGATIVE-DIRECTED slices/ranges step is MANDATORY. It is BY DESIGN of python and we follow this convention too. Always set step for all the ranges if you may deal with negative-directed ones.

For the info on usage see the docstrings and tests. And READ the source code, it is SMALL ENOUGH.

Features

Notation and terms:

• For briefness we r = range and s = slice
• When we say range, it also works for a slice and in the opposite direction too.

Conventions:

• When we say range or slice, it usually works also for a sequence of them. See type annotations to check if a specific function supports sequences of ranges.

• There may be undefined behavior (UB):

  • negative-directed ranges without negative step is always UB;
  • non-integer numbers usage is always UB;;
  • operations on the ranges having different abs(step);
  • empty ranges (ranges of zero length) produced may (but not guaranteed) be eliminated;
  • operations on the ranges having opposite direction may be UB. It should be stated in docstrings if it is the case.

• basic operations

  • type conversion:

    • sAny2Type(s(1, 10), r) -> r(1, 10) sAny2Type(r(1, 10), s) -> s(1, 10)
    • range2slice and slice2range do the same.

  • get a length of a range slen(s(2, 4)) -> 2. For usual ranges just len works, but our func works also for slices and seqs.

  • get direction (a director vector in fact) of a slice sdir(r(10, 1, -2)) -> -1

  • reverse direction of a slice: srev(r(0, 10)) -> r(9, -1, -1)

  • make 2 slices of the same direction: sdirect(r(25, 5, -5), s(1, 10)) -> slice(9, 0, -1)

  • make a slice positive-directed: snormalize(r(25, 5, -5)) -> range(10, 30, 5)

• checking conditions about ranges:

  • check if one range is fully within another range swithin(r(0, 10), r(1, 5)) -> true
  • check if one range is overlaps another range soverlaps(r(0, 10), r(2, -6, -1)) -> true

• splitting

  • sprit a range at certain points: ssplit(r(5, 13), (7, 8, 12)) -> [r(5, 7), r(7, 8), r(8, 12), r(12, 13)]
  • split a range into pieces of certain lengths soffset_split(r(5, 13), (2, 3, 7)) -> [r(5, 7), r(7, 8), r(8, 12), r(12, 13)]
  • split a range into pieces of a certain length schunks(r(5, 13), 3) -> [r(5, 8), r(8, 11), r(11, 13)]
  • split multiple sequences of ranges of the same total length into the chunks of equal length, in other words - align split points of all the sequence - see the docs for salign function.

• join/merge adjacent (non-overlapping!) ranges into one: sjoin([r(0, 8), r(8, 9), r(9, 10), r(12, 15)]) -> [r(0, 10), r(12, 15)]

• set operations

  • compute a diff of 2 ranges: sdiff
  • subtract 2 ranges: ssub(r(1, 10), r(5, -10, -1)) -> [r(6, 10)]
  • union 2 ranges: sunion(r(1, 10), r(7, 20)) -> [r(1, 20)]

• intersections querying via a range tree

• remapping via a SliceSequence

• visualization

Examples

• https://codeberg.org/kaitaiStructCompile/Endianness.py
• tests

Similar projects

• intervaltree
• rangetree