class Set

Copyright © 2002-2024 Akinori MUSHA <knu@iDaemons.org>

Documentation by Akinori MUSHA and Gavin Sinclair.

All rights reserved. You can redistribute and/or modify it under the same terms as Ruby.

The Set class implements a collection of unordered values with no duplicates. It is a hybrid of Array’s intuitive inter-operation facilities and Hash’s fast lookup.

Set is easy to use withEnumerable objects (implementing ‘each`). Most of the initializer methods and binary operators accept genericEnumerable objects besides sets and arrays. AnEnumerable object can be converted to Set using the `to_set` method.

Set uses a data structure similar toHash for storage, except that it only has keys and no values.

Comparison

The comparison operators<,>,<=, and>= are implemented as shorthand for the {proper_,}{subset?,superset?} methods. The<=> operator reflects this order, or returnsnil for sets that both have distinct elements ({x, y} vs.{x, z} for example).

Example

s1 =Set[1,2]#=> #<Set: {1, 2}>s2 = [1,2].to_set#=> #<Set: {1, 2}>s1==s2#=> trues1.add("foo")#=> #<Set: {1, 2, "foo"}>s1.merge([2,6])#=> #<Set: {1, 2, "foo", 6}>s1.subset?(s2)#=> falses2.subset?(s1)#=> true

Contact

What’s Here

First, what's elsewhere. \Class \Set:

In particular, class Set does not have many methods of its own for fetching or for iterating. Instead, it relies on those in Enumerable.

Here, class Set provides methods that are useful for:

Methods for Creating a Set

Methods for Set Operations

Methods for Comparing

Methods for Querying

Methods for Assigning

Methods for Deleting

Methods for Converting

Methods for Iterating

Other Methods

Public Class Methods

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static VALUEset_s_create(int argc, VALUE *argv, VALUE klass){    VALUE set = set_alloc_with_size(klass, argc);    set_table *table = RSET_TABLE(set);    int i;    for (i=0; i < argc; i++) {        set_table_insert_wb(table, set, argv[i], NULL);    }    return set;}

Returns a new Set object populated with the given objects, SeeSet::new.

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# File ext/json/lib/json/add/set.rb, line 9defself.json_create(object)newobject['a']end

Seeas_json.

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static VALUEset_i_initialize(int argc, VALUE *argv, VALUE set){    if (RBASIC(set)->flags & RSET_INITIALIZED) {        rb_raise(rb_eRuntimeError, "cannot reinitialize set");    }    RBASIC(set)->flags |= RSET_INITIALIZED;    VALUE other;    rb_check_arity(argc, 0, 1);    if (argc > 0 && (other = argv[0]) != Qnil) {        if (RB_TYPE_P(other, T_ARRAY)) {            long i;            int block_given = rb_block_given_p();            set_table *into = RSET_TABLE(set);            for (i=0; i<RARRAY_LEN(other); i++) {                VALUE key = RARRAY_AREF(other, i);                if (block_given) key = rb_yield(key);                set_table_insert_wb(into, set, key, NULL);            }        }        else {            ID id_size = rb_intern("size");            if (rb_obj_is_kind_of(other, rb_mEnumerable) && rb_respond_to(other, id_size)) {                VALUE size = rb_funcall(other, id_size, 0);                if (RB_TYPE_P(size, T_FLOAT) && RFLOAT_VALUE(size) == INFINITY) {                    rb_raise(rb_eArgError, "cannot initialize Set from an object with infinite size");                }            }            rb_block_call(other, enum_method_id(other), 0, 0,                rb_block_given_p() ? set_initialize_with_block : set_initialize_without_block,                set);        }    }    return set;}

Creates a new set containing the elements of the given enumerable object.

If a block is given, the elements of enum are preprocessed by the given block.

Set.new([1,2])#=> #<Set: {1, 2}>Set.new([1,2,1])#=> #<Set: {1, 2}>Set.new([1,'c',:s])#=> #<Set: {1, "c", :s}>Set.new(1..5)#=> #<Set: {1, 2, 3, 4, 5}>Set.new([1,2,3]) {|x|x*x }#=> #<Set: {1, 4, 9}>

Public Instance Methods

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static VALUEset_i_intersection(VALUE set, VALUE other){    VALUE new_set = set_s_alloc(rb_obj_class(set));    set_table *stable = RSET_TABLE(set);    set_table *ntable = RSET_TABLE(new_set);    if (rb_obj_is_kind_of(other, rb_cSet)) {        set_table *otable = RSET_TABLE(other);        if (set_table_size(stable) >= set_table_size(otable)) {            /* Swap so we iterate over the smaller set */            otable = stable;            set = other;        }        struct set_intersection_data data = {            .set = new_set,            .into = ntable,            .other = otable        };        set_iter(set, set_intersection_i, (st_data_t)&data);    }    else {        struct set_intersection_data data = {            .set = new_set,            .into = ntable,            .other = stable        };        rb_block_call(other, enum_method_id(other), 0, 0, set_intersection_block, (VALUE)&data);    }    return new_set;}

Returns a new set containing elements common to the set and the given enumerable object.

Set[1,3,5]&Set[3,2,1]#=> #<Set: {3, 1}>Set['a','b','z']& ['a','b','c']#=> #<Set: {"a", "b"}>
Also aliased as:intersection
Alias for:|
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static VALUEset_i_difference(VALUE set, VALUE other){    return set_i_subtract(rb_obj_dup(set), other);}

Returns a new set built by duplicating the set, removing every element that appears in the given enumerable object.

Set[1,3,5]-Set[1,5]#=> #<Set: {3}>Set['a','b','z']- ['a','c']#=> #<Set: {"b", "z"}>
Also aliased as:difference
Alias for:proper_subset?
Alias for:add
Alias for:subset?
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static VALUEset_i_compare(VALUE set, VALUE other){    if (rb_obj_is_kind_of(other, rb_cSet)) {        size_t set_size = RSET_SIZE(set);        size_t other_size = RSET_SIZE(other);        if (set_size < other_size) {            if (set_le(set, other) == Qtrue) {                return INT2NUM(-1);            }        }        else if (set_size > other_size) {            if (set_le(other, set) == Qtrue) {                return INT2NUM(1);            }        }        else if (set_le(set, other) == Qtrue) {            return INT2NUM(0);        }    }    return Qnil;}

Returns 0 if the set are equal, -1 / 1 if the set is a proper subset / superset of the given set, or or nil if they both have unique elements.

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static VALUEset_i_eq(VALUE set, VALUE other){    if (!rb_obj_is_kind_of(other, rb_cSet)) return Qfalse;    if (set == other) return Qtrue;    set_table *stable = RSET_TABLE(set);    set_table *otable = RSET_TABLE(other);    size_t ssize = set_table_size(stable);    size_t osize = set_table_size(otable);    if (ssize != osize) return Qfalse;    if (ssize == 0 && osize == 0) return Qtrue;    if (stable->type != otable->type) return Qfalse;    struct set_equal_data data;    data.set = other;    return rb_exec_recursive_paired(set_recursive_eql, set, other, (VALUE)&data);}

Returns true if two sets are equal.

Also aliased as:eql?
Alias for:include?
Alias for:proper_superset?
Alias for:superset?
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static VALUEset_i_xor(VALUE set, VALUE other){    VALUE new_set;    if (rb_obj_is_kind_of(other, rb_cSet)) {        new_set = other;    }    else {        new_set = set_s_alloc(rb_obj_class(set));        set_merge_enum_into(new_set, other);    }    set_iter(set, set_xor_i, (st_data_t)new_set);    return new_set;}

Returns a new set containing elements exclusive between the set and the given enumerable object.(set ^ enum) is equivalent to((set | enum) - (set & enum)).

Set[1,2]^Set[2,3]#=> #<Set: {3, 1}>Set[1,'b','c']^ ['b','d']#=> #<Set: {"d", 1, "c"}>
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static VALUEset_i_union(VALUE set, VALUE other){    set = rb_obj_dup(set);    set_merge_enum_into(set, other);    return set;}

Returns a new set built by merging the set and the elements of the given enumerable object.

Set[1,2,3]|Set[2,4,5]#=> #<Set: {1, 2, 3, 4, 5}>Set[1,5,'z']| (1..6)#=> #<Set: {1, 5, "z", 2, 3, 4, 6}>
Also aliased as:+,union
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static VALUEset_i_add(VALUE set, VALUE item){    rb_check_frozen(set);    if (set_iterating_p(set)) {        if (!set_table_lookup(RSET_TABLE(set), (st_data_t)item)) {            no_new_item();        }    }    else {        set_insert_wb(set, item, NULL);    }    return set;}

Adds the given object to the set and returns self. Use ‘merge` to add many elements at once.

Set[1,2].add(3)#=> #<Set: {1, 2, 3}>Set[1,2].add([3,4])#=> #<Set: {1, 2, [3, 4]}>Set[1,2].add(2)#=> #<Set: {1, 2}>
Also aliased as:<<
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static VALUEset_i_add_p(VALUE set, VALUE item){    rb_check_frozen(set);    if (set_iterating_p(set)) {        if (!set_table_lookup(RSET_TABLE(set), (st_data_t)item)) {            no_new_item();        }        return Qnil;    }    else {        return set_insert_wb(set, item, NULL) ? Qnil : set;    }}

Adds the given object to the set and returns self. If the object is already in the set, returns nil.

Set[1,2].add?(3)#=> #<Set: {1, 2, 3}>Set[1,2].add?([3,4])#=> #<Set: {1, 2, [3, 4]}>Set[1,2].add?(2)#=> nil
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# File ext/json/lib/json/add/set.rb, line 28defas_json(*)  {JSON.create_id=>self.class.name,'a'=>to_a,  }end

MethodsSet#as_json andSet.json_create may be used to serialize and deserialize a Set object; seeMarshal.

MethodSet#as_json serializesself, returning a 2-element hash representingself:

require'json/add/set'x =Set.new(%w/foo bar baz/).as_json# => {"json_class"=>"Set", "a"=>["foo", "bar", "baz"]}

MethodJSON.create deserializes such a hash, returning a Set object:

Set.json_create(x)# => #<Set: {"foo", "bar", "baz"}>
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static VALUEset_i_classify(VALUE set){    RETURN_SIZED_ENUMERATOR(set, 0, 0, set_enum_size);    VALUE args[2];    args[0] = rb_hash_new();    args[1] = rb_obj_class(set);    set_iter(set, set_classify_i, (st_data_t)args);    return args[0];}

Classifies the set by the return value of the given block and returns a hash of {value => set of elements} pairs. The block is called once for each element of the set, passing the element as parameter.

files =Set.new(Dir.glob("*.rb"))hash =files.classify {|f|File.mtime(f).year }hash#=> {2000 => #<Set: {"a.rb", "b.rb"}>,#    2001 => #<Set: {"c.rb", "d.rb", "e.rb"}>,#    2002 => #<Set: {"f.rb"}>}

Returns an enumerator if no block is given.

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static VALUEset_i_clear(VALUE set){    rb_check_frozen(set);    if (RSET_SIZE(set) == 0) return set;    if (set_iterating_p(set)) {        set_iter(set, set_clear_i, 0);    }    else {        set_table_clear(RSET_TABLE(set));        set_compact_after_delete(set);    }    return set;}

Removes all elements and returns self.

set =Set[1,'c',:s]#=> #<Set: {1, "c", :s}>set.clear#=> #<Set: {}>set#=> #<Set: {}>
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static VALUEset_i_collect(VALUE set){    RETURN_SIZED_ENUMERATOR(set, 0, 0, set_enum_size);    rb_check_frozen(set);    VALUE new_set = set_s_alloc(rb_obj_class(set));    set_iter(set, set_collect_i, (st_data_t)new_set);    set_i_initialize_copy(set, new_set);    return set;}

Replaces the elements with ones returned bycollect. Returns an enumerator if no block is given.

Also aliased as:map!
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static VALUEset_i_compare_by_identity(VALUE set){    if (RSET_COMPARE_BY_IDENTITY(set)) return set;    if (set_iterating_p(set)) {        rb_raise(rb_eRuntimeError, "compare_by_identity during iteration");    }    return set_reset_table_with_type(set, &identhash);}

Makes the set compare its elements by their identity and returns self.

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static VALUEset_i_compare_by_identity_p(VALUE set){    return RBOOL(RSET_COMPARE_BY_IDENTITY(set));}

Returns true if the set will compare its elements by their identity. Also seeSet#compare_by_identity.

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static VALUEset_i_delete(VALUE set, VALUE item){    rb_check_frozen(set);    if (set_table_delete(RSET_TABLE(set), (st_data_t *)&item)) {        set_compact_after_delete(set);    }    return set;}

Deletes the given object from the set and returns self. Use subtract to delete many items at once.

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static VALUEset_i_delete_p(VALUE set, VALUE item){    rb_check_frozen(set);    if (set_table_delete(RSET_TABLE(set), (st_data_t *)&item)) {        set_compact_after_delete(set);        return set;    }    return Qnil;}

Deletes the given object from the set and returns self. If the object is not in the set, returns nil.

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static VALUEset_i_delete_if(VALUE set){    RETURN_SIZED_ENUMERATOR(set, 0, 0, set_enum_size);    rb_check_frozen(set);    set_iter(set, set_delete_if_i, 0);    set_compact_after_delete(set);    return set;}

Deletes every element of the set for which block evaluates to true, and returns self. Returns an enumerator if no block is given.

Alias for:-
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static VALUEset_i_disjoint(VALUE set, VALUE other){    return RBOOL(!RTEST(set_i_intersect(set, other)));}

Returns true if the set and the given enumerable have no element in common. This method is the opposite ofintersect?.

Set[1,2,3].disjoint?Set[3,4]#=> falseSet[1,2,3].disjoint?Set[4,5]#=> trueSet[1,2,3].disjoint? [3,4]#=> falseSet[1,2,3].disjoint?4..5#=> true
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static VALUEset_i_divide(VALUE set){    RETURN_SIZED_ENUMERATOR(set, 0, 0, set_enum_size);    if (rb_block_arity() == 2) {        return set_divide_arity2(set);    }    VALUE values = rb_hash_values(set_i_classify(set));    set = set_alloc_with_size(rb_cSet, RARRAY_LEN(values));    set_merge_enum_into(set, values);    return set;}

Divides the set into a set of subsets according to the commonality defined by the given block.

If the arity of the block is 2, elements o1 and o2 are in common if both block.call(o1, o2) and block.call(o2, o1) are true. Otherwise, elements o1 and o2 are in common if block.call(o1) == block.call(o2).

numbers =Set[1,3,4,6,9,10,11]set =numbers.divide {|i,j| (i-j).abs==1 }set#=> #<Set: {#<Set: {1}>,#           #<Set: {3, 4}>,#           #<Set: {6}>}>#           #<Set: {9, 10, 11}>,

Returns an enumerator if no block is given.

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static VALUEset_i_each(VALUE set){    RETURN_SIZED_ENUMERATOR(set, 0, 0, set_enum_size);    set_iter(set, set_each_i, 0);    return set;}

Calls the given block once for each element in the set, passing the element as parameter. Returns an enumerator if no block is given.

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static VALUEset_i_empty(VALUE set){    return RBOOL(RSET_EMPTY(set));}

Returns true if the set contains no elements.

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# File ext/psych/lib/psych/core_ext.rb, line 27defencode_with(coder)hash = {}eachdo|m|hash[m] =trueendcoder["hash"] =hashcoderend
Alias for:==
Alias for:select!
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static VALUEset_i_flatten(VALUE set){    VALUE new_set = set_s_alloc(rb_obj_class(set));    set_flatten_merge(new_set, set, rb_hash_new());    return new_set;}

Returns a new set that is a copy of the set, flattening each containing set recursively.

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static VALUEset_i_flatten_bang(VALUE set){    bool contains_set = false;    set_iter(set, set_contains_set_i, (st_data_t)&contains_set);    if (!contains_set) return Qnil;    rb_check_frozen(set);    return set_i_replace(set, set_i_flatten(set));}

Equivalent toSet#flatten, but replaces the receiver with the result in place. Returns nil if no modifications were made.

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static VALUEset_i_hash(VALUE set){    st_index_t size = RSET_SIZE(set);    st_index_t hval = rb_st_hash_start(size);    hval = rb_hash_uint(hval, (st_index_t)set_i_hash);    if (size) {        set_iter(set, set_hash_i, (VALUE)&hval);    }    hval = rb_st_hash_end(hval);    return ST2FIX(hval);}

Returns hash code for set.

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static VALUEset_i_include(VALUE set, VALUE item){    return RBOOL(RSET_IS_MEMBER(set, item));}

Returns true if the set contains the given object:

Set[1,2,3].include?2#=> trueSet[1,2,3].include?4#=> false

Note thatinclude? andmember? do not test member equality using== as do other Enumerables.

This is aliased to===, so it is usable incase expressions:

case:applewhenSet[:potato,:carrot]"vegetable"whenSet[:apple,:banana]"fruit"end# => "fruit"

See alsoEnumerable#include?

Also aliased as:member?,===
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# File ext/psych/lib/psych/core_ext.rb, line 36definit_with(coder)replace(coder["hash"].keys)end
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static VALUEset_i_inspect(VALUE set){    return rb_exec_recursive(set_inspect, set, 0);}

Returns a new string containing the set entries:

s =Set.news.inspect# => "#<Set: {}>"s.add(1)s.inspect# => "#<Set: {1}>"s.add(2)s.inspect# => "#<Set: {1, 2}>"

Related: seeMethods for Converting.

Also aliased as:to_s
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static VALUEset_i_intersect(VALUE set, VALUE other){    if (rb_obj_is_kind_of(other, rb_cSet)) {        size_t set_size = RSET_SIZE(set);        size_t other_size = RSET_SIZE(other);        VALUE args[2];        args[1] = Qfalse;        VALUE iter_arg;        if (set_size < other_size) {            iter_arg = set;            args[0] = (VALUE)RSET_TABLE(other);        }        else {            iter_arg = other;            args[0] = (VALUE)RSET_TABLE(set);        }        set_iter(iter_arg, set_intersect_i, (st_data_t)args);        return args[1];    }    else if (rb_obj_is_kind_of(other, rb_mEnumerable)) {        return rb_funcall(other, id_any_p, 1, set);    }    else {        rb_raise(rb_eArgError, "value must be enumerable");    }}

Returns true if the set and the given enumerable have at least one element in common.

Set[1,2,3].intersect?Set[4,5]#=> falseSet[1,2,3].intersect?Set[3,4]#=> trueSet[1,2,3].intersect?4..5#=> falseSet[1,2,3].intersect? [3,4]#=> true
Alias for:&
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static VALUEset_i_join(int argc, VALUE *argv, VALUE set){    rb_check_arity(argc, 0, 1);    return rb_ary_join(set_i_to_a(set), argc == 0 ? Qnil : argv[0]);}

Returns a string created by converting each element of the set to a string.

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static VALUEset_i_keep_if(VALUE set){    RETURN_SIZED_ENUMERATOR(set, 0, 0, set_enum_size);    rb_check_frozen(set);    set_iter(set, set_keep_if_i, (st_data_t)RSET_TABLE(set));    return set;}

Deletes every element of the set for which block evaluates to false, and returns self. Returns an enumerator if no block is given.

Alias for:size
Alias for:collect!
Alias for:include?
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static VALUEset_i_merge(int argc, VALUE *argv, VALUE set){    if (rb_keyword_given_p()) {        rb_raise(rb_eArgError, "no keywords accepted");    }    if (set_iterating_p(set)) {        rb_raise(rb_eRuntimeError, "cannot add to set during iteration");    }    rb_check_frozen(set);    int i;    for (i=0; i < argc; i++) {        set_merge_enum_into(set, argv[i]);    }    return set;}

Merges the elements of the given enumerable objects to the set and returns self.

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static VALUEset_i_proper_subset(VALUE set, VALUE other){    check_set(other);    if (RSET_SIZE(set) >= RSET_SIZE(other)) return Qfalse;    return set_le(set, other);}

Returns true if the set is a proper subset of the given set.

Also aliased as:<
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static VALUEset_i_proper_superset(VALUE set, VALUE other){    check_set(other);    if (RSET_SIZE(set) <= RSET_SIZE(other)) return Qfalse;    return set_le(other, set);}

Returns true if the set is a proper superset of the given set.

Also aliased as:>
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static VALUEset_i_reject(VALUE set){    RETURN_SIZED_ENUMERATOR(set, 0, 0, set_enum_size);    rb_check_frozen(set);    set_table *table = RSET_TABLE(set);    size_t n = set_table_size(table);    set_iter(set, set_delete_if_i, 0);    if (n == set_table_size(table)) return Qnil;    set_compact_after_delete(set);    return set;}

Equivalent toSet#delete_if, but returns nil if no changes were made. Returns an enumerator if no block is given.

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static VALUEset_i_replace(VALUE set, VALUE other){    rb_check_frozen(set);    if (rb_obj_is_kind_of(other, rb_cSet)) {        set_i_initialize_copy(set, other);    }    else {        if (set_iterating_p(set)) {            rb_raise(rb_eRuntimeError, "cannot replace set during iteration");        }        // make sure enum is enumerable before calling clear        enum_method_id(other);        set_table_clear(RSET_TABLE(set));        set_merge_enum_into(set, other);    }    return set;}

Replaces the contents of the set with the contents of the given enumerable object and returns self.

set =Set[1,'c',:s]#=> #<Set: {1, "c", :s}>set.replace([1,2])#=> #<Set: {1, 2}>set#=> #<Set: {1, 2}>
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static VALUEset_i_reset(VALUE set){    if (set_iterating_p(set)) {        rb_raise(rb_eRuntimeError, "reset during iteration");    }    return set_reset_table_with_type(set, RSET_TABLE(set)->type);}

Resets the internal state after modification to existing elements and returns self. Elements will be reindexed and deduplicated.

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static VALUEset_i_select(VALUE set){    RETURN_SIZED_ENUMERATOR(set, 0, 0, set_enum_size);    rb_check_frozen(set);    set_table *table = RSET_TABLE(set);    size_t n = set_table_size(table);    set_iter(set, set_keep_if_i, (st_data_t)table);    return (n == set_table_size(table)) ? Qnil : set;}

Equivalent toSet#keep_if, but returns nil if no changes were made. Returns an enumerator if no block is given.

Also aliased as:filter!
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static VALUEset_i_size(VALUE set){    return RSET_SIZE_NUM(set);}

Returns the number of elements.

Also aliased as:length
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static VALUEset_i_subset(VALUE set, VALUE other){    check_set(other);    if (RSET_SIZE(set) > RSET_SIZE(other)) return Qfalse;    return set_le(set, other);}

Returns true if the set is a subset of the given set.

Also aliased as:<=
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static VALUEset_i_subtract(VALUE set, VALUE other){    rb_check_frozen(set);    set_remove_enum_from(set, other);    return set;}

Deletes every element that appears in the given enumerable object and returns self.

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static VALUEset_i_superset(VALUE set, VALUE other){    check_set(other);    if (RSET_SIZE(set) < RSET_SIZE(other)) return Qfalse;    return set_le(other, set);}

Returns true if the set is a superset of the given set.

Also aliased as:>=
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static VALUEset_i_to_a(VALUE set){    st_index_t size = RSET_SIZE(set);    VALUE ary = rb_ary_new_capa(size);    if (size == 0) return ary;    if (ST_DATA_COMPATIBLE_P(VALUE)) {        RARRAY_PTR_USE(ary, ptr, {            size = set_keys(RSET_TABLE(set), ptr, size);        });        rb_gc_writebarrier_remember(ary);        rb_ary_set_len(ary, size);    }    else {        set_iter(set, set_to_a_i, (st_data_t)ary);    }    return ary;}

Returns an array containing all elements in the set.

Set[1,2].to_a#=> [1, 2]Set[1,'c',:s].to_a#=> [1, "c", :s]
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# File ext/json/lib/json/add/set.rb, line 44defto_json(*args)as_json.to_json(*args)end

Returns aJSON string representingself:

require'json/add/set'putsSet.new(%w/foo bar baz/).to_json

Output:

{"json_class":"Set","a":["foo","bar","baz"]}
Alias for:inspect
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static VALUEset_i_to_set(int argc, VALUE *argv, VALUE set){    VALUE klass;    if (argc == 0) {        klass = rb_cSet;        argv = &set;        argc = 1;    }    else {        rb_warn_deprecated("passing arguments to Set#to_set", NULL);        klass = argv[0];        argv[0] = set;    }    if (klass == rb_cSet && rb_obj_is_instance_of(set, rb_cSet) &&            argc == 1 && !rb_block_given_p()) {        return set;    }    return rb_funcall_passing_block(klass, id_new, argc, argv);}

Returns self if receiver is an instance ofSet and no arguments or block are given. Otherwise, converts the set to another withklass.new(self, *args, &block).

In subclasses, returns ‘klass.new(self, *args, &block)` unless overridden.

Alias for:|