Description:

cyclicsequences 1.1.2

Cyclic-Sequences################Sequence type objects with cyclic indexing::Description===========The cyclic indexation works as for usual sequences, with the possible use of negative indexes. But it makes a jump-back to the beginning (or the end for negative indexes) if the index is higher than the length of the sequence:: ┌───────────────────────────┐ │ ▼ ┏━│━┳━━━┳━━━┳━╍┅ ┅╍━┳━━━━━┳━━━┳━━━┓ ┃ ● ┃ 0 ┃ 1 ┃ ⋅⋅⋅ ┃ N-1 ┃ N ┃ ● ┃ ┗━━━┻━━━┻━━━┻━╍┅ ┅╍━┻━━━━━┻━━━┻━│━┛ ▲ │ └───────────────────────────┘Iterating over a cyclic sequence is bounded (no infinite loop)... note:: This module is based on a Chris Lawlor forum publication.Content=======:CyclicTuple: Class object. An immutable cyclic sequence based on built-in class *tuple*.:CyclicList: Class object. A mutable cyclic sequence based on built-in class *list*.:CyclicStr: Class object. An immutable cyclic sequence based on built-in class *str*.Immutable class methods-----------------------:with_first: foo.with_first(elt) -> new instance New instance of 'foo' with first occurence of 'elt' at first position. Raises ValueError if 'elt' is not present.:turned: foo.turned(step) -> new instance New instance of 'foo' with all elements shifted of given step. (default is 1 unit onward).Mutable class methods---------------------:set_first: foo.set_first(elt) -> None Set first occurence of 'elt' at first position. Raises ValueError if 'elt' is not present.:turn: foo.turn(step) -> None Change all elements indexes of given step (default is 1 unit onward) Equivalent to set at first position the element at index 'step'.Examples========The following examples are using CyclicList class for demonstration. CyclicTuple and CyclicStr classes get similar behaviours.- Construction from any iterable:: >>> foo = CyclicList(['a', 'b', 'c', 'd', 'e']) >>> foo CyclicList(['a', 'b', 'c', 'd', 'e'])- Gets its specific string representation with chevrons figuring cycling:: >>> print(foo) <['a', 'b', 'c', 'd', 'e']>- Accessing works like a regular list:: >>> foo[1] 'b' >>> foo[-4] 'b'- Except indexes higher than length wraps around:: >>> foo[6] 'b' >>> foo[11] 'b' >>> foo[-9] 'b'- Slices work and return list objects:: >>> foo[1:4] ['b', 'c', 'd'] >>> foo[3:0:-1] ['d', 'c', 'b']- Slices work also out of range with cyclic output:: >>> foo[3:7] ['d', 'e', 'a', 'b'] >>> foo[8:12] ['d', 'e', 'a', 'b'] >>> foo[3:12] ['d', 'e', 'a', 'b', 'c', 'd', 'e', 'a', 'b'] >>> foo[-2:2] ['d', 'e', 'a', 'b'] >>> foo[-7:-3] ['d', 'e', 'a', 'b'] >>> foo[-7:2] ['d', 'e', 'a', 'b', 'c', 'd', 'e', 'a', 'b']- Slices with non unitary steps work also:: >>> foo[:7:2] ['a', 'c', 'e', 'b'] >>> foo[:7:3] ['a', 'd', 'b'] >>> foo[:7:5] ['a', 'a']- As well for reversed steps:: >>> foo[1:-3:-1] ['b', 'a', 'e', 'd'] >>> foo[-4:-8:-1] ['b', 'a', 'e', 'd'] >>> foo[-4:-9:-2] ['b', 'e', 'c'] >>> foo[-4:-9:-3] ['b', 'd'] >>> foo[-5:-11:-5] ['a', 'a']- Incoherent slices return empty list:: >>> foo[11:5] []Edge effects:- Indexing an empty CyclicList returns an IndexError.- Indexing on a unique element returns always this element.First element can be played with using specific methods:- **with_first**: return a new CyclicList with given element at first position:: >>> foo.with_first('c') CyclicList(['c', 'd', 'e', 'a', 'b'])- **turned**: return a new CyclicList with all elements indexes changed of given step (default is 1 unit onward):: >>> foo.turned() CyclicList(['b', 'c', 'd', 'e', 'a']) >>> foo.turned(-3) CyclicList(['c', 'd', 'e', 'a', 'b']) >>> foo.turned(10) CyclicList(['a', 'b', 'c', 'd', 'e'])- **set_first**: put given element at first position:: >>> foo.set_first('c') >>> foo CyclicList(['c', 'd', 'e', 'a', 'b'])- **turn**: change all elements index of given step (default is 1 unit onward):: >>> foo.turn() >>> foo CyclicList(['d', 'e', 'a', 'b', 'c']) >>> foo.turn(-3) >>> foo CyclicList(['a', 'b', 'c', 'd', 'e']) >>> foo.turn(11) >>> foo CyclicList(['b', 'c', 'd', 'e', 'a'])

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