The StringRange class

Class for generating strings in a given range and in a particular order.

The StringRange class implements a range object for strings and produces the same output as WordRange() | ToString("ab") , but is more convenient in some cases.

The order and range of the words in a StringRange instance can be set using the member functions:

StringRange.order
StringRange.alphabet
StringRange.min
StringRange.max
StringRange.first
StringRange.last

See also

WordRange

Example

>>> from libsemigroups_pybind11 import StringRange, Order
>>> strings = StringRange();
>>> strings.order(Order.shortlex) \
...        .alphabet("ba") \
...        .min(1) \
...        .max(5)
<StringRange of length 30 in shortlex order>
>>> strings.order()
<Order.shortlex: 1>

>>> from libsemigroups_pybind11 import ToWord
>>> strings.alphabet("a").min(0).max(10)
<StringRange of length 10 in shortlex order>

>>> wrds = strings | ToWord("a")
>>> list(wrds)
[[], [0], [0, 0], [0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0]]

Contents

`StringRange`	Class for generating strings in a given range and in a particular order.
`StringRange.alphabet`(…)	Overloaded function.
`StringRange.at_end`(…)	Check if the range object is exhausted.
`StringRange.copy`(…)	Copy a `StringRange` object.
`StringRange.count`(…)	The actual size of the range.
`StringRange.first`(…)	Overloaded function.
`StringRange.get`(…)	Get the current value.
`StringRange.init`(…)	Initialize an existing `StringRange` object.
`StringRange.last`(…)	Overloaded function.
`StringRange.max`(…)	Set one past the last string in the range by length.
`StringRange.min`(…)	Set the first string in the range by length.
`StringRange.next`(…)	Advance to the next value.
`StringRange.order`(…)	Overloaded function.
`StringRange.size_hint`(…)	The possible size of the range.
`StringRange.upper_bound`(…)	Overloaded function.

Full API

class StringRange

__init__(self: StringRange) → None

Default constructor. Constructs an empty range with:

StringRange.min() equal to 0 ;
StringRange.max() equal to 0 ;
StringRange.order() equal to Order.shortlex ;
StringRange.first() equal to the empty string;
StringRange.last() equal to the empty string;
StringRange.upper_bound() equal to 0 ;
StringRange.alphabet() equal to the empty string.

alphabet(*args, **kwargs)

Overloaded function.

alphabet(self: StringRange) → str

The current alphabet.

Returns the current alphabet in a StringRange object.

Returns:: The current alphabet.
Return type:: str

alphabet(self: StringRange, x: str) → StringRange

Set the alphabet.

Sets the alphabet in a StringRange object.

Parameters:: x (str) – the alphabet.
Returns:: self.
Return type:: StringRange
Raises:: LibsemigroupsError – if x contains repeated letters.

at_end(self: StringRange) → bool

Check if the range object is exhausted.

Returns True if a StringRange object is exhausted, and False if not.

Returns:: Whether the object is exhausted.
Return type:: bool

copy(self: StringRange) → StringRange

Copy a StringRange object.

Returns:: A copy.
Return type:: StringRange

count(self: StringRange) → int

The actual size of the range.

Returns the number of strings in the range object. If StringRange.order() is Order.shortlex , then StringRange.size_hint() is used. If order() is not Order.shortlex , then a copy of the range may have to be looped over in order to find the return value of this function.

Returns:: The size of the range.
Return type:: int

first(*args, **kwargs)

Overloaded function.

first(self: StringRange) → str

The current first string in the range.

Returns the first string in a StringRange object.

Returns:: The first string.
Return type:: str

See also

min

first(self: StringRange, frst: str) → StringRange

Set the first string in the range.

Sets the first string in a StringRange object to be frst.

Parameters:: frst (str) – the first string.
Returns:: self.
Return type:: StringRange

See also

min

get(self: StringRange) → str

Get the current value.

Returns the current string in a StringRange object.

Returns:: The current value.
Return type:: str

init(self: StringRange) → StringRange

Initialize an existing StringRange object.

This function puts a StringRange object back into the same state as if it had been newly default constructed.

Returns:: self.
Return type:: StringRange

last(*args, **kwargs)

Overloaded function.

last(self: StringRange) → str

The current one past the last string in the range.

Returns one past the last string in a StringRange object.

Returns:: One past the last string.
Return type:: str

See also

max

last(self: StringRange, lst: str) → StringRange

Set one past the last string in the range.

Sets one past the last string in a StringRange object to be lst.

Parameters:: lst (str) – the first string.
Returns:: self.
Return type:: StringRange
Raises:: LibsemigroupsError – if lst contains letters not belonging to StringRange.alphabet().

See also

max

max(self: StringRange, val: int) → StringRange

Set one past the last string in the range by length.

Sets one past the last string in a StringRange object to be \(\alpha^n\) where \(\alpha\) is the first letter of StringRange.alphabet (or "a" if the alphabet is empty) and \(n\) corresponds to val.

Parameters:: val (int) – the exponent.
Returns:: self.
Return type:: StringRange

min(self: StringRange, val: int) → StringRange

Set the first string in the range by length.

Sets the first string in a StringRange object to be \(\alpha^n\) where \(\alpha\) is the first letter of StringRange.alphabet (or "a" if the alphabet is empty) and \(n\) corresponds to val.

Parameters:: val (int) – the exponent.
Returns:: self.
Return type:: StringRange

next(self: StringRange) → None

Advance to the next value.

Advances a StringRange object to the next value (if any).

See also

at_end

order(*args, **kwargs)

Overloaded function.

order(self: StringRange) → Order

The current order of the strings in the range.

Returns the current order of the strings in a StringRange object.

Returns:: The current order.
Return type:: Order

order(self: StringRange, val: Order) → StringRange

Set the order of the strings in the range.

Sets the order of the strings in a StringRange object to val.

Parameters:: val (Order) – the order.
Returns:: self.
Return type:: StringRange
Raises:: LibsemigroupsError – if val is not Order.shortlex or Order.lex.

size_hint(self: StringRange) → int

The possible size of the range.

Returns the number of words in a StringRange object if StringRange.order() is Order.shortlex. If order() is not Order.shortlex , then the return value of this function is meaningless.

Returns:: A value of type int.
Return type:: int

upper_bound(self: StringRange, n: int) → StringRange

Overloaded function.

upper_bound(self: StringRange) → int

The current upper bound on the length of a string in the range.

Returns the current upper bound on the length of a string in a StringRange object. This setting is only used if StringRange.order() is Order.lex.

Returns:: A value of type int.
Return type:: int

upper_bound(self: StringRange, n: int) → StringRange

Set an upper bound for the length of a string in the range.

Sets an upper bound for the length of a string in a StringRange object. This setting is only used if StringRange.order() is Order.lex.

Parameters:: n (int) – the upper bound.
Returns:: self.
Return type:: StringRange