class MixHash
Mutable collection of distinct objects with Real weights
does Mixy
A MixHash
is a mutable mix, meaning a collection of distinct elements in no particular order that each have a real-number weight assigned to them. (For immutable mixes, see Mix instead.)
Objects/values of any type are allowed as mix elements. Within a MixHash
, items that would compare positively with the === operator are considered the same element, with a combined weight.
my = (butter => 0.22, sugar => 0.1,flour => 0.275, sugar => 0.02).MixHash;say .elems; # OUTPUT: «3»say .keys.sort; # OUTPUT: «butter flour sugar»say .pairs.sort; # OUTPUT: «"butter" => 0.22 "flour" => 0.275 "sugar" => 0.12»say .total; # OUTPUT: «0.615»
MixHash
es can be treated as object hashes using the { }
postcircumfix operator, which returns the corresponding numeric weight for keys that are elements of the mix, and 0
for keys that aren't. It can also be used to modify weights; Setting a weight to 0
automatically removes that element from the mix, and setting a weight to a non-zero number adds that element if it didn't already exist:
my = (butter => 0.22, sugar => 0.1,flour => 0.275, sugar => 0.02).MixHash;say <butter>; # OUTPUT: «0.22»say <sugar>; # OUTPUT: «0.12»say <chocolate>; # OUTPUT: «0»<butter> = 0;<chocolate> = 0.30;say .pairs; # OUTPUT: «"sugar" => 0.12 "flour" => 0.275 "chocolate" => 0.3»
Creating MixHash
objects
MixHash
es can be composed using MixHash.new
. Any positional parameters, regardless of their type, become elements of the mix - with a weight of 1
for each time the parameter occurred:
my = MixHash.new: "a", "a", "b" => 0, "c" => 3.14;say .keys.map(); # OUTPUT: «((Str) (Pair) (Pair))»say .pairs; # OUTPUT: «(a => 2 (c => 3.14) => 1 (b => 0) => 1)»
Alternatively, the .MixHash
coercer (or its functional form, MixHash()
) can be called on an existing object to coerce it to a MixHash
. Its semantics depend on the type and contents of the object. In general it evaluates the object in list context and creates a mix with the resulting items as elements, although for Hash-like objects or Pair items, only the keys become elements of the mix, and the (cumulative) values become the associated numeric weights:
my = ("a", "a", "b" => 0, "c" => 3.14).MixHash;say .keys.map(); # OUTPUT: «((Str) (Str))»say .pairs; # OUTPUT: «(a => 2 c => 3.14)»
Since 6.d (2019.03 and later) it is also possible to specify the type of values you would like to allow in a MixHash
. This can either be done when calling .new
:
# only allow stringsmy = MixHash[Str].new: <a b b c c c>;
or using the masquerading syntax:
# only allow stringsmy is MixHash[Str] = <a b b c c c>;say <b>; # 2say <d>; # 0# only allow whole numbersmy is MixHash[Int] = <a b b c c c>;# Type check failed in binding; expected Int but got Str ("a")
Operators
my (, ) = MixHash(2 => 2, 4), MixHash(2 => 1.5, 3 => 2, 4);say (<) ; # OUTPUT: «False»say (<+) ; # OUTPUT: «False»say (^) ; # OUTPUT: «Mix(2(0.5), 3(2))»say (+) ; # OUTPUT: «Mix(2(3.5), 4(2), 3(2))»# Unicode versions:say ⊂ ; # OUTPUT: «False»say ≼ ; # OUTPUT: «False»say ⊖ ; # OUTPUT: «Mix(2(0.5), 3(2))»say ⊎ ; # OUTPUT: «Mix(2(3.5), 4(2), 3(2))»
See Set/Bag Operators for a complete list of set and bag operators with detailed explanations.
Note on reverse
and ordering.
MixHash inherits reverse
from Any, however, Mix
es do not have an inherent order and you should not trust it returning a consistent output.
If you sort a MixHash, the result is a list of pairs, at which point reverse
makes perfect sense:
my = MixHash.new(2, 2, 18, 3, 4);say ; # OUTPUT: «MixHash(18, 2(2), 3, 4)»say .sort; # OUTPUT: «(2 => 2 3 => 1 4 => 1 18 => 1)»say .sort.reverse; # OUTPUT: «(18 => 1 4 => 1 3 => 1 2 => 2)»
Methods
method Bag
Defined as:
method Bag (--> Bag)
Coerces the MixHash
to a Bag
. The weights are converted to Int
, which means the number of keys in the resulting Bag
can be fewer than in the original MixHash
, if any of the weights are negative or truncate to zero.
method BagHash
Defined as:
method BagHash (--> BagHash)
Coerces the MixHash
to a BagHash
. The weights are converted to Int
, which means the number of keys in the resulting BagHash
can be fewer than in the original MixHash
, if any of the weights are negative or truncate to zero.
Note on reverse
and ordering
This method is inherited from Any, however, Mix
es do not have an inherent order and you should not trust it returning a consistent output.
See Also
Type Graph
Routines supplied by role Mixy
MixHash does role Mixy, which provides the following routines:
(Mixy) method total
method total(--> Real)
Returns the sum of all the weights
say mix('a', 'b', 'c', 'a', 'a', 'd').total == 6; # OUTPUT: «True»say %(a => 5.6, b => 2.4).Mix.total == 8; # OUTPUT: «True»
(Mixy) method roll
method roll( = 1)
Similar to a Bag.roll, but with Real
weights rather than integral ones.
Routines supplied by role Baggy
MixHash does role Baggy, which provides the following routines:
(Baggy) method new-from-pairs
Defined as:
method new-from-pairs(* --> Baggy)
Constructs a Baggy objects from a list of Pair
objects given as positional arguments:
say Mix.new-from-pairs: 'butter' => 0.22, 'sugar' => 0.1, 'sugar' => 0.02;# OUTPUT: «mix(butter(0.22), sugar(0.12))»
Note: be sure you aren't accidentally passing the Pairs as positional arguments; the quotes around the keys in the above example are significant.
(Baggy) method grab
Defined as:
multi method grab(Baggy: --> Any)multi method grab(Baggy: --> Seq)
Like pick, a grab
returns a random selection of elements, weighted by the values corresponding to each key. Unlike pick
, it works only on mutable structures, e.g. BagHash. Use of grab
on an immutable structure results in an X::Immutable
exception. If *
is passed as $count
, or $count
is greater than or equal to the total of the invocant, then total
elements from the invocant are returned in a random sequence; i.e. they are returned shuffled.
Grabbing decrements the grabbed key's weight by one (deleting the key when it reaches 0). By definition, the total
of the invocant also decreases by one, so the probabilities stay consistent through subsequent grab
operations.
my = ('Ford' => 2, 'Rover' => 3).BagHash;say .grab; # OUTPUT: «Ford»say .grab(2); # OUTPUT: «(Rover Rover)»say .grab(*); # OUTPUT: «(Rover Ford)»my = ('eggs' => 2, 'bacon' => 3).Bag;say .grab;CATCH ;# OUTPUT: «X::Immutable: Cannot call 'grab' on an immutable 'Bag'»
(Baggy) method grabpairs
Defined as:
multi method grabpairs(Baggy: --> Any)multi method grabpairs(Baggy: --> Seq)
Returns a Pair
or a Seq
of Pair
s depending on the version of the method being invoked. Each Pair
returned has an element of the invocant as its key and the elements weight as its value. Unlike pickpairs, it works only on mutable structures, e.g. BagHash. Use of grabpairs
on 'an immutable structure results in an X::Immutable
exception. If *
is passed as $count
, or $count
is greater than or equal to the number of elements of the invocant, then all element/weight Pair
s from the invocant are returned in a random sequence.
What makes grabpairs
different from pickpairs is that the 'grabbed' elements are in fact removed from the invocant.
my = (eggs => 2, bacon => 3).BagHash;say .grabpairs; # OUTPUT: «bacon => 3»say ; # OUTPUT: «BagHash.new(eggs(2))»say .grabpairs(1); # OUTPUT: «(eggs => 2)»say .grabpairs(*); # OUTPUT: «()»my = ('eggs' => 2, 'bacon' => 3).Bag;say .grabpairs;CATCH ;# OUTPUT: «X::Immutable: Cannot call 'grabpairs' on an immutable 'Bag'»
(Baggy) method pick
Defined as:
multi method pick(Baggy: --> Any)multi method pick(Baggy: --> Seq)
Like an ordinary list pick, but returns keys of the invocant weighted by their values, as if the keys were replicated the number of times indicated by the corresponding value and then list pick used. The underlying metaphor for picking is that you're pulling colored marbles out a bag. (For "picking with replacement" see roll instead). If *
is passed as $count
, or $count
is greater than or equal to the total of the invocant, then total
elements from the invocant are returned in a random sequence.
Note that each pick
invocation maintains its own private state and has no effect on subsequent pick
invocations.
my = bag <eggs bacon bacon bacon>;say .pick; # OUTPUT: «eggs»say .pick(2); # OUTPUT: «(eggs bacon)»say .total; # OUTPUT: «4»say .pick(*); # OUTPUT: «(bacon bacon bacon eggs)»
(Baggy) method pickpairs
Defined as:
multi method pickpairs(Baggy: --> Pair)multi method pickpairs(Baggy: --> Seq)
Returns a Pair
or a Seq
of Pair
s depending on the version of the method being invoked. Each Pair
returned has an element of the invocant as its key and the elements weight as its value. The elements are 'picked' without replacement. If *
is passed as $count
, or $count
is greater than or equal to the number of elements of the invocant, then all element/weight Pair
s from the invocant are returned in a random sequence.
Note that each pickpairs
invocation maintains its own private state and has no effect on subsequent pickpairs
invocations.
my = bag <eggs bacon bacon bacon>;say .pickpairs; # OUTPUT: «eggs => 1»say .pickpairs(1); # OUTPUT: «(bacon => 3)»say .pickpairs(*); # OUTPUT: «(eggs => 1 bacon => 3)»
(Baggy) method roll
Defined as:
multi method roll(Baggy: --> Any)multi method roll(Baggy: --> Seq)
Like an ordinary list roll, but returns keys of the invocant weighted by their values, as if the keys were replicated the number of times indicated by the corresponding value and then list roll used. The underlying metaphor for rolling is that you're throwing $count
dice that are independent of each other, which (in bag terms) is equivalent to picking a colored marble out your bag and then putting it back, and doing this $count
times. In dice terms, the number of marbles corresponds to the number of sides, and the number of marbles of the same color corresponds to the number of sides with the same color. (For "picking without replacement" see pick instead).
If *
is passed to $count
, returns a lazy, infinite sequence of randomly chosen elements from the invocant.
my = bag <eggs bacon bacon bacon>;say .roll; # OUTPUT: «bacon»say .roll(3); # OUTPUT: «(bacon eggs bacon)»my := .roll(*);say [^5]; # OUTPUT: «(bacon eggs bacon bacon bacon)»
(Baggy) method pairs
Defined as:
method pairs(Baggy: --> Seq)
Returns all elements and their respective weights as a Seq of Pair
s where the key is the element itself and the value is the weight of that element.
my = bag <bacon eggs bacon>;my = .pairs;say .sort; # OUTPUT: «(bacon => 2 eggs => 1)»
(Baggy) method antipairs
Defined as:
method antipairs(Baggy: --> Seq)
Returns all elements and their respective weights as a Seq of Pairs, where the element itself is the value and the weight of that element is the key, i.e. the opposite of method pairs.
my = bag <bacon eggs bacon>;my = .antipairs;say .sort; # OUTPUT: «(1 => eggs 2 => bacon)»
(Baggy) method invert
Defined as:
method invert(Baggy: --> Seq)
Returns all elements and their respective weights as a Seq of Pairs, where the element itself is the value and the weight of that element is the key, i.e. the opposite of method pairs. Except for some esoteric cases invert
on a Baggy type returns the same result as antipairs.
my = bag <bacon eggs bacon>;my = .invert;say .sort; # OUTPUT: «(1 => eggs 2 => bacon)»
(Baggy) method classify-list
Defined as:
multi method classify-list(, * --> Baggy)multi method classify-list(, * --> Baggy)multi method classify-list(, * --> Baggy)
Populates a mutable Baggy
by classifying the possibly-empty @list
of values using the given mapper
. The @list
cannot be lazy.
say BagHash.new.classify-list: , ^10;# OUTPUT: BagHash.new(even(5), odd(5))my = <zero one two three four five>;say MixHash.new.classify-list: , 1, 2, 3, 4, 4, 6;# OUTPUT: MixHash.new((Any), two, three, four(2), one)
The mapper can be a Callable
that takes a single argument, an Associative
, or an Iterable
. With Associative
and an Iterable
mappers, the values in the @list
represent the key and index of the mapper's value respectively. A Callable
mapper will be executed once per each item in the @list
, with that item as the argument and its return value will be used as the mapper's value.
The mapper's value is used as the key of the Baggy
that will be incremented by 1
. See .categorize-list
if you wish to classify an item into multiple categories at once.
Note: unlike the Hash
's .classify-list
, returning an Iterable
mapper's value will throw, as Baggy
types do not support nested classification. For the same reason, Baggy
's .classify-list
does not accept :&as
parameter.
(Baggy) method categorize-list
Defined as:
multi method categorize-list(, * --> Baggy)multi method categorize-list(, * --> Baggy)multi method categorize-list(, * --> Baggy)
Populates a mutable Baggy
by categorizing the possibly-empty @list
of values using the given mapper
. The @list
cannot be lazy.
say BagHash.new.categorize-list:, ^10;# OUTPUT: BagHash.new(largish(4), even(5), non-prime(6), prime(4), odd(5))my = :sugar<sweet white>, :lemon<sour>, :cake('sweet', 'is a lie');say MixHash.new.categorize-list: , <sugar lemon cake>;# OUTPUT: MixHash.new(is a lie, sour, white, sweet(2))
The mapper can be a Callable
that takes a single argument, an Associative
, or an Iterable
. With Associative
and an Iterable
mappers, the values in the @list
represent the key and index of the mapper's value respectively. A Callable
mapper will be executed once per each item in the @list
, with that item as the argument and its return value will be used as the mapper's value.
The mapper's value is used as a possibly-empty list of keys of the Baggy
that will be incremented by 1
.
Note: unlike the Hash
's .categorize-list
, returning a list of Iterables
as mapper's value will throw, as Baggy
types do not support nested categorization. For the same reason, Baggy
's .categorize-list
does not accept :&as
parameter.
(Baggy) method keys
Defined as:
method keys(Baggy: --> Seq)
Returns a Seq
of all keys in the Baggy
object without taking their individual weights into account as opposed to kxxv.
my = bag <eggs spam spam spam>;say .keys.sort; # OUTPUT: «(eggs spam)»my = ("a" => 5, "b" => 2).BagHash;say .keys.sort; # OUTPUT: «(a b)»
(Baggy) method values
Defined as:
method values(Baggy: --> Seq)
Returns a Seq
of all values, i.e. weights, in the Baggy
object.
my = bag <eggs spam spam spam>;say .values.sort; # OUTPUT: «(1 3)»my = ("a" => 5, "b" => 2, "a" => 1).BagHash;say .values.sort; # OUTPUT: «(2 6)»
(Baggy) method kv
Defined as:
method kv(Baggy: --> Seq)
Returns a Seq
of keys and values interleaved.
my = bag <eggs spam spam spam>;say .kv; # OUTPUT: «(spam 3 eggs 1)»my = ("a" => 5, "b" => 2, "a" => 1).BagHash;say .kv; # OUTPUT: «(a 6 b 2)»
(Baggy) method kxxv
Defined as:
method kxxv(Baggy: --> Seq)
Returns a Seq
of the keys of the invocant, with each key multiplied by its weight. Note that kxxv
only works for Baggy
types which have integer weights, i.e. Bag and BagHash.
my = bag <spam eggs spam spam bacon>;say .kxxv.sort; # OUTPUT: «(bacon eggs spam spam spam)»my = ("a" => 0, "b" => 1, "b" => 2).BagHash;say .kxxv; # OUTPUT: «(b b b)»
(Baggy) method elems
Defined as:
method elems(Baggy: --> Int)
Returns the number of elements in the Baggy
object without taking the individual elements weight into account.
my = bag <eggs spam spam spam>;say .elems; # OUTPUT: «2»my = ("b" => 9.4, "b" => 2).MixHash;say .elems; # OUTPUT: «1»
(Baggy) method total
Defined as:
method total(Baggy:)
Returns the sum of weights for all elements in the Baggy
object.
my = bag <eggs spam spam bacon>;say .total; # OUTPUT: «4»my = ("a" => 5, "b" => 1, "b" => 2).BagHash;say .total; # OUTPUT: «8»
(Baggy) method default
Defined as:
method default(Baggy: --> Int)
Returns zero.
my = bag <eggs bacon>;say .default; # OUTPUT: «0»
(Baggy) method hash
Defined as:
method hash(Baggy: --> Hash)
Returns a Hash where the elements of the invocant are the keys and their respective weights the values.
my = bag <eggs bacon bacon>;my = .hash;say .^name; # OUTPUT: «Hash[Any,Any]»say ; # OUTPUT: «{bacon => 2, eggs => 1}»
(Baggy) method Bool
Defined as:
method Bool(Baggy: --> Bool)
Returns True
if the invocant contains at least one element.
my = ('eggs' => 1).BagHash;say .Bool; # OUTPUT: «True (since we have one element)»<eggs> = 0; # weight == 0 will lead to element removalsay .Bool; # OUTPUT: «False»
(Baggy) method Set
Defined as:
method Set(--> Set)
Returns a Set whose elements are the keys of the invocant.
my = (eggs => 2, bacon => 3).BagHash;say .Set; # OUTPUT: «set(bacon, eggs)»
(Baggy) method SetHash
Defined as:
method SetHash(--> SetHash)
Returns a SetHash whose elements are the keys of the invocant.
my = (eggs => 2, bacon => 3).BagHash;my = .SetHash;say .^name; # OUTPUT: «SetHash»say .elems; # OUTPUT: «2»
(Baggy) method ACCEPTS
Defined as:
method ACCEPTS( --> Bool)
Used in smartmatching if the right-hand side is a Baggy
.
If the right-hand side is the type object, i.e. Baggy
, the method returns True
if $other
does Baggy
otherwise False
is returned.
If the right-hand side is a Baggy
object, True
is returned only if $other
has the same elements, with the same weights, as the invocant.
my = bag <eggs bacon>;say ~~ Baggy; # OUTPUT: «True»say .does(Baggy); # OUTPUT: «True»my = (eggs => 1, bacon => 1).Mix;say ~~ ; # OUTPUT: «True»my = (eggs => 1, bacon => 2).Bag;say ~~ ; # OUTPUT: «False»
Routines supplied by role QuantHash
MixHash does role QuantHash, which provides the following routines:
(QuantHash) method hash
method hash()
Coerces the QuantHash
object to a Hash (by stringifying the objects for the keys) with the values of the hash limited to the same limitation as QuantHash
, and returns that.
(QuantHash) method Hash
method Hash()
Coerces the QuantHash
object to a Hash (by stringifying the objects for the keys) without any limitations on the values, and returns that.
(QuantHash) method of
method of()
Returns the type of value a value of this QuantHash
may have. This is typically Bool for Setty, UInt for Baggy or Real for Mixy roles.
(QuantHash) method keyof
method keyof()
Returns the type of value a key of this QuantHash
may have. This is typically Mu.
(QuantHash) method Setty
method Setty(--> Setty)
Coerce the QuantHash
object to the equivalent object that uses the Setty role. Note that for Mixy type coercion items with negative values will be skipped.
my is Bag = one => 1, two => 2;say .Setty; # OUTPUT: «set(one two)»my is Mix = one => 1, minus => -1;say .Setty; # OUTPUT: «set(one)»
(QuantHash) method Baggy
method Baggy(--> Baggy)
Coerce the QuantHash
object to the equivalent object that uses the Baggy role. Note that for Mixy type coercion items with negative values will be skipped.
my is Set = <one two>;say .Baggy; # OUTPUT: «Bag(one, two)»my is Mix = one => 1, minus => -1;say .Baggy; # OUTPUT: «Bag(one)»
(QuantHash) method Mixy
method Mixy(--> Mixy)
Coerce the QuantHash
object to the equivalent object that uses the Mixy role.
my is Set = <one two>;say .Mixy; # OUTPUT: «Mix(one, two)»my is Bag = one => 1, two => 2;say .Mixy; # OUTPUT: «Mix(one, two)»
Routines supplied by role Associative
MixHash does role Associative, which provides the following routines:
(Associative) method of
Defined as:
method of()
Associative
is actually a parameterized role which can use different classes for keys and values. As seen at the top of the document, by default it coerces to Str
for the key and uses a very generic Mu
for value.
my ;say .of;# OUTPUT: «(Mu)»
The value is the first parameter you use when instantiating Associative
with particular classes:
is Hash does Associative[Cool,DateTime] ;my := DateHash.new;say .of; # OUTPUT: «(Cool)»
(Associative) method keyof
Defined as:
method keyof()
Returns the parameterized key used for the Associative role, which is Any
coerced to Str
by default. This is the class used as second parameter when you use the parameterized version of Associative.
my ;.keyof; #OUTPUT: «(Str(Any))»
(Associative) method AT-KEY
method AT-KEY(\key)
Should return the value / container at the given key.
(Associative) method EXISTS-KEY
method EXISTS-KEY(\key)
Should return a Bool
indicating whether the given key actually has a value.
(Associative) method STORE
method STORE(\values, :)
This method should only be supplied if you want to support the:
my is Foo = a => 42, b => 666;
syntax for binding your implementation of the Associative
role.
Should accept the values to (re-)initialize the object with, which either could consist of Pair
s, or separate key/value pairs. The optional named parameter will contain a True
value when the method is called on the object for the first time. Should return the invocant.