The sets module implements an efficient hash set and ordered hash set.
Hash sets are different from the built in set type. Sets allow you to store any value that can be hashed and they don't contain duplicate entries.
Common usages of sets:
- removing duplicates from a container by converting it with toHashSet proc (see also sequtils.deduplicate func)
- membership testing
- mathematical operations on two sets, such as union, intersection, difference, and symmetric difference
echo toHashSet([9, 5, 1]) # {9, 1, 5} echo toOrderedSet([9, 5, 1]) # {9, 5, 1} let s1 = toHashSet([9, 5, 1]) s2 = toHashSet([3, 5, 7]) echo s1 + s2 # {9, 1, 3, 5, 7} echo s1 - s2 # {1, 9} echo s1 * s2 # {5} echo s1 -+- s2 # {9, 1, 3, 7}
Note: The data types declared here have value semantics: This means that = performs a copy of the set.
See also:
- intsets module for efficient int sets
- tables module for hash tables
Types
HashSet[A] {..} = object
-
A generic hash set.
Use init proc or initHashSet proc before calling other procs on it.
Source Edit OrderedSet[A] {..} = object
-
A generic hash set that remembers insertion order.
Use init proc or initOrderedSet proc before calling other procs on it.
Source Edit SomeSet[A] = HashSet[A] | OrderedSet[A]
- Type union representing HashSet or OrderedSet. Source Edit
Procs
proc `$`[A](s: HashSet[A]): string
-
Converts the set s to a string, mostly for logging and printing purposes.
Don't use this proc for serialization, the representation may change at any moment and values are not escaped.
Examples:
echo toHashSet([2, 4, 5]) # --> {2, 4, 5} echo toHashSet(["no", "esc'aping", "is \" provided"]) # --> {no, esc'aping, is " provided}
Source Edit proc `$`[A](s: OrderedSet[A]): string
-
Converts the ordered hash set s to a string, mostly for logging and printing purposes.
Don't use this proc for serialization, the representation may change at any moment and values are not escaped.
Examples:
echo toOrderedSet([2, 4, 5]) # --> {2, 4, 5} echo toOrderedSet(["no", "esc'aping", "is \" provided"]) # --> {no, esc'aping, is " provided}
Source Edit proc `<`[A](s, t: HashSet[A]): bool
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Returns true if s is a strict or proper subset of t.
A strict or proper subset s has all of its members in t but t has more elements than s.
Example:
let a = toHashSet(["a", "b"]) b = toHashSet(["b", "c"]) c = intersection(a, b) assert c < a and c < b assert(not (a < a))
Source Edit proc `<=`[A](s, t: HashSet[A]): bool
-
Returns true if s is a subset of t.
A subset s has all of its members in t and t doesn't necessarily have more members than s. That is, s can be equal to t.
Example:
let a = toHashSet(["a", "b"]) b = toHashSet(["b", "c"]) c = intersection(a, b) assert c <= a and c <= b assert a <= a
Source Edit proc `==`[A](s, t: HashSet[A]): bool
-
Returns true if both s and t have the same members and set size.
Example:
var a = toHashSet([1, 2]) b = toHashSet([2, 1]) assert a == b
Source Edit proc `==`[A](s, t: OrderedSet[A]): bool
-
Equality for ordered sets.
Example:
let a = toOrderedSet([1, 2]) b = toOrderedSet([2, 1]) assert(not (a == b))
Source Edit proc card[A](s: HashSet[A]): int
-
Alias for len().
Card stands for the cardinality of a set.
Source Edit proc card[A](s: OrderedSet[A]): int {.inline.}
-
Alias for len().
Card stands for the cardinality of a set.
Source Edit proc clear[A](s: var HashSet[A])
-
Clears the HashSet back to an empty state, without shrinking any of the existing storage.
O(n) operation, where n is the size of the hash bucket.
See also:
Example:
var s = toHashSet([3, 5, 7]) clear(s) assert len(s) == 0
Source Edit proc clear[A](s: var OrderedSet[A])
-
Clears the OrderedSet back to an empty state, without shrinking any of the existing storage.
O(n) operation where n is the size of the hash bucket.
Example:
var s = toOrderedSet([3, 5, 7]) clear(s) assert len(s) == 0
Source Edit proc contains[A](s: HashSet[A]; key: A): bool
-
Returns true if key is in s.
This allows the usage of in operator.
See also:
Example:
var values = initHashSet[int]() assert(not values.contains(2)) assert 2 notin values values.incl(2) assert values.contains(2) assert 2 in values
Source Edit proc contains[A](s: OrderedSet[A]; key: A): bool
-
Returns true if key is in s.
This allows the usage of in operator.
See also:
Example:
var values = initOrderedSet[int]() assert(not values.contains(2)) assert 2 notin values values.incl(2) assert values.contains(2) assert 2 in values
Source Edit proc containsOrIncl[A](s: var HashSet[A]; key: A): bool
-
Includes key in the set s and tells if key was already in s.
The difference with regards to the incl proc is that this proc returns true if s already contained key. The proc will return false if key was added as a new value to s during this call.
See also:
- incl proc for including an element
- incl proc for including other set
- missingOrExcl proc
Example:
var values = initHashSet[int]() assert values.containsOrIncl(2) == false assert values.containsOrIncl(2) == true assert values.containsOrIncl(3) == false
Source Edit proc containsOrIncl[A](s: var OrderedSet[A]; key: A): bool
-
Includes key in the set s and tells if key was already in s.
The difference with regards to the incl proc is that this proc returns true if s already contained key. The proc will return false if key was added as a new value to s during this call.
See also:
- incl proc for including an element
- missingOrExcl proc
Example:
var values = initOrderedSet[int]() assert values.containsOrIncl(2) == false assert values.containsOrIncl(2) == true assert values.containsOrIncl(3) == false
Source Edit proc difference[A](s1, s2: HashSet[A]): HashSet[A]
-
Returns the difference of the sets s1 and s2.
The same as s1 - s2.
The difference of two sets is represented mathematically as A ∖ B and is the set of all objects that are members of s1 and not members of s2.
See also:
Example:
let a = toHashSet(["a", "b"]) b = toHashSet(["b", "c"]) c = difference(a, b) assert c == toHashSet(["a"])
Source Edit proc excl[A](s: var HashSet[A]; key: A)
-
Excludes key from the set s.
This doesn't do anything if key is not found in s.
See also:
- incl proc for including an element
- excl proc for excluding other set
- missingOrExcl proc
Example:
var s = toHashSet([2, 3, 6, 7]) s.excl(2) s.excl(2) assert s.len == 3
Source Edit proc excl[A](s: var HashSet[A]; other: HashSet[A])
-
Excludes all elements of other set from s.
This is the in-place version of s - other.
See also:
- incl proc for including other set
- excl proc for excluding an element
- missingOrExcl proc
Example:
var numbers = toHashSet([1, 2, 3, 4, 5]) even = toHashSet([2, 4, 6, 8]) numbers.excl(even) assert len(numbers) == 3 ## numbers == {1, 3, 5}
Source Edit proc excl[A](s: var OrderedSet[A]; key: A)
-
Excludes key from the set s. Efficiency: O(n).
This doesn't do anything if key is not found in s.
See also:
- incl proc for including an element
- missingOrExcl proc
Example:
var s = toOrderedSet([2, 3, 6, 7]) s.excl(2) s.excl(2) assert s.len == 3
Source Edit proc hash[A](s: OrderedSet[A]): Hash
- Hashing of OrderedSet. Source Edit
proc incl[A](s: var HashSet[A]; key: A)
-
Includes an element key in s.
This doesn't do anything if key is already in s.
See also:
- excl proc for excluding an element
- incl proc for including other set
- containsOrIncl proc
Example:
var values = initHashSet[int]() values.incl(2) values.incl(2) assert values.len == 1
Source Edit proc incl[A](s: var HashSet[A]; other: HashSet[A])
-
Includes all elements from other set into s (must be declared as var).
This is the in-place version of s + other.
See also:
- excl proc for excluding other set
- incl proc for including an element
- containsOrIncl proc
Example:
var values = toHashSet([1, 2, 3]) others = toHashSet([3, 4, 5]) values.incl(others) assert values.len == 5
Source Edit proc incl[A](s: var HashSet[A]; other: OrderedSet[A])
-
Includes all elements from the OrderedSet other into HashSet s (must be declared as var).
See also:
- incl proc for including an element
- containsOrIncl proc
Example:
var values = toHashSet([1, 2, 3]) others = toOrderedSet([3, 4, 5]) values.incl(others) assert values.len == 5
Source Edit proc incl[A](s: var OrderedSet[A]; key: A)
-
Includes an element key in s.
This doesn't do anything if key is already in s.
See also:
- excl proc for excluding an element
- incl proc for including other set
- containsOrIncl proc
Example:
var values = initOrderedSet[int]() values.incl(2) values.incl(2) assert values.len == 1
Source Edit proc init[A](s: var HashSet[A]; initialSize = defaultInitialSize)
-
Initializes a hash set.
Starting from Nim v0.20, sets are initialized by default and it is not necessary to call this function explicitly.
You can call this proc on a previously initialized hash set, which will discard all its values. This might be more convenient than iterating over existing values and calling excl() on them.
See also:
Example:
var a: HashSet[int] init(a)
Source Edit proc init[A](s: var OrderedSet[A]; initialSize = defaultInitialSize)
-
Initializes an ordered hash set.
Starting from Nim v0.20, sets are initialized by default and it is not necessary to call this function explicitly.
You can call this proc on a previously initialized hash set, which will discard all its values. This might be more convenient than iterating over existing values and calling excl() on them.
See also:
Example:
var a: OrderedSet[int] init(a)
Source Edit proc initHashSet[A](initialSize = defaultInitialSize): HashSet[A]
-
Wrapper around init proc for initialization of hash sets.
Returns an empty hash set you can assign directly in var blocks in a single line.
Starting from Nim v0.20, sets are initialized by default and it is not necessary to call this function explicitly.
See also:
Example:
var a = initHashSet[int]() a.incl(3) assert len(a) == 1
Source Edit proc initOrderedSet[A](initialSize = defaultInitialSize): OrderedSet[A]
-
Wrapper around init proc for initialization of ordered hash sets.
Returns an empty ordered hash set you can assign directly in var blocks in a single line.
Starting from Nim v0.20, sets are initialized by default and it is not necessary to call this function explicitly.
See also:
Example:
var a = initOrderedSet[int]() a.incl(3) assert len(a) == 1
Source Edit proc intersection[A](s1, s2: HashSet[A]): HashSet[A]
-
Returns the intersection of the sets s1 and s2.
The same as s1 * s2.
The intersection of two sets is represented mathematically as A ∩ B and is the set of all objects that are members of s1 and s2 at the same time.
See also:
Example:
let a = toHashSet(["a", "b"]) b = toHashSet(["b", "c"]) c = intersection(a, b) assert c == toHashSet(["b"])
Source Edit proc isValid[A](s: HashSet[A]): bool {....deprecated: "Deprecated since v0.20; sets are initialized by default".}
-
true if the set has been initialized (with initHashSet proc or init proc).
Example:
proc savePreferences(options: HashSet[string]) = assert options.isValid, "Pass an initialized set!" # Do stuff here, may crash in release builds!
Source Edit
Returns proc len[A](s: HashSet[A]): int
-
Returns the number of elements in s.
Due to an implementation detail you can call this proc on variables which have not been initialized yet. The proc will return zero as the length then.
Example:
var a: HashSet[string] assert len(a) == 0 let s = toHashSet([3, 5, 7]) assert len(s) == 3
Source Edit proc len[A](s: OrderedSet[A]): int {.inline.}
-
Returns the number of elements in s.
Due to an implementation detail you can call this proc on variables which have not been initialized yet. The proc will return zero as the length then.
Example:
var a: OrderedSet[string] assert len(a) == 0 let s = toHashSet([3, 5, 7]) assert len(s) == 3
Source Edit proc map[A, B](data: HashSet[A]; op: proc (x: A): B {.closure.}): HashSet[B] {. effectsOf: op.}
-
Returns a new set after applying op proc on each of the elements of data set.
You can use this proc to transform the elements from a set.
Example:
let a = toHashSet([1, 2, 3]) b = a.map(proc (x: int): string = $x) assert b == toHashSet(["1", "2", "3"])
Source Edit proc missingOrExcl[A](s: var HashSet[A]; key: A): bool
-
Excludes key in the set s and tells if key was already missing from s.
The difference with regards to the excl proc is that this proc returns true if key was missing from s. The proc will return false if key was in s and it was removed during this call.
See also:
- excl proc for excluding an element
- excl proc for excluding other set
- containsOrIncl proc
Example:
var s = toHashSet([2, 3, 6, 7]) assert s.missingOrExcl(4) == true assert s.missingOrExcl(6) == false assert s.missingOrExcl(6) == true
Source Edit proc missingOrExcl[A](s: var OrderedSet[A]; key: A): bool
-
Excludes key in the set s and tells if key was already missing from s. Efficiency: O(n).
The difference with regards to the excl proc is that this proc returns true if key was missing from s. The proc will return false if key was in s and it was removed during this call.
See also:
Example:
var s = toOrderedSet([2, 3, 6, 7]) assert s.missingOrExcl(4) == true assert s.missingOrExcl(6) == false assert s.missingOrExcl(6) == true
Source Edit proc symmetricDifference[A](s1, s2: HashSet[A]): HashSet[A]
-
Returns the symmetric difference of the sets s1 and s2.
The same as s1 -+- s2.
The symmetric difference of two sets is represented mathematically as A △ B or A ⊖ B and is the set of all objects that are members of s1 or s2 but not both at the same time.
See also:
Example:
let a = toHashSet(["a", "b"]) b = toHashSet(["b", "c"]) c = symmetricDifference(a, b) assert c == toHashSet(["a", "c"])
Source Edit proc toHashSet[A](keys: openArray[A]): HashSet[A]
-
Creates a new hash set that contains the members of the given collection (seq, array, or string) keys.
Duplicates are removed.
See also:
Example:
let a = toHashSet([5, 3, 2]) b = toHashSet("abracadabra") assert len(a) == 3 ## a == {2, 3, 5} assert len(b) == 5 ## b == {'a', 'b', 'c', 'd', 'r'}
Source Edit proc toOrderedSet[A](keys: openArray[A]): OrderedSet[A]
-
Creates a new hash set that contains the members of the given collection (seq, array, or string) keys.
Duplicates are removed.
See also:
Example:
let a = toOrderedSet([5, 3, 2]) b = toOrderedSet("abracadabra") assert len(a) == 3 ## a == {5, 3, 2} # different than in HashSet assert len(b) == 5 ## b == {'a', 'b', 'r', 'c', 'd'} # different than in HashSet
Source Edit proc union[A](s1, s2: HashSet[A]): HashSet[A]
-
Returns the union of the sets s1 and s2.
The same as s1 + s2.
The union of two sets is represented mathematically as A ∪ B and is the set of all objects that are members of s1, s2 or both.
See also:
Example:
let a = toHashSet(["a", "b"]) b = toHashSet(["b", "c"]) c = union(a, b) assert c == toHashSet(["a", "b", "c"])
Source Edit
Iterators
iterator items[A](s: HashSet[A]): A
-
Iterates over elements of the set s.
If you need a sequence with the elements you can use sequtils.toSeq template.
type pair = tuple[a, b: int] var a, b = initHashSet[pair]() a.incl((2, 3)) a.incl((3, 2)) a.incl((2, 3)) for x, y in a.items: b.incl((x - 2, y + 1)) assert a.len == 2 echo b # --> {(a: 1, b: 3), (a: 0, b: 4)}
Source Edit iterator items[A](s: OrderedSet[A]): A
-
Iterates over keys in the ordered set s in insertion order.
If you need a sequence with the elements you can use sequtils.toSeq template.
var a = initOrderedSet[int]() for value in [9, 2, 1, 5, 1, 8, 4, 2]: a.incl(value) for value in a.items: echo "Got ", value # --> Got 9 # --> Got 2 # --> Got 1 # --> Got 5 # --> Got 8 # --> Got 4
Source Edit iterator pairs[A](s: OrderedSet[A]): tuple[a: int, b: A]
-
Iterates through (position, value) tuples of OrderedSet s.
Example:
let a = toOrderedSet("abracadabra") var p = newSeq[(int, char)]() for x in pairs(a): p.add(x) assert p == @[(0, 'a'), (1, 'b'), (2, 'r'), (3, 'c'), (4, 'd')]
Source Edit