Ruby

Thu Nov 27 15:29:06 2014 Brian Hempel <plasticchicken@gmail.com>

* enum.c: New methods Enumerable#{frequencies,relative_frequencies}

Counts the number of times each item appears in an Enumerable.

* test/ruby/test_enum.rb: Tests for new methods.

frequencies_i(RB_BLOCK_CALL_FUNC_ARGLIST(i, hash))

{

VALUE freq;

long freql;

ENUM_WANT_SVALUE();

freq = rb_hash_aref(hash, i);

if (!RB_TYPE_P(freq, T_FIXNUM)) {

freq = INT2FIX(0);

}

freql = FIX2LONG(freq);

freq = LONG2FIX(freql+1);

rb_hash_aset(hash, i, freq);

return Qnil;

}

static VALUE

frequencies_sort_by_i(RB_BLOCK_CALL_FUNC_ARGLIST(i, dummy))

{

VALUE freq;

freq = RARRAY_AREF(i, 1);

return LONG2FIX(-FIX2LONG(freq));

}

/*

* call-seq:

* enum.frequencies -> a_hash

*

* Counts the number of times each object appears in <i>enum</i>.

* Returns a hash where the keys are objects from <i>enum</i> and the

* values are the number of times the object occurs in <i>enum</i>.

*

* The hash is sorted, with the most common objects first.

*

* %w[cat bird bird horse].frequencies

* #=> {"bird" => 2, "horse" => 1, "cat" => 1}

*

*/

static VALUE

enum_frequencies(VALUE obj)

{

VALUE hash;

VALUE sorted;

hash = rb_hash_new();

rb_block_call(obj, id_each, 0, 0, frequencies_i, hash);

sorted = rb_block_call(hash, rb_intern("sort_by"), 0, 0, frequencies_sort_by_i, 0);

hash = rb_funcall(sorted, rb_intern("to_h"), 0);

OBJ_INFECT(hash, obj);

return hash;

}

static VALUE

relative_frequencies_i(RB_BLOCK_CALL_FUNC_ARGLIST(i, memop))

{

NODE *memo = RNODE(memop);

VALUE hash = memo->u1.value;

VALUE freq;

long freql;

ENUM_WANT_SVALUE();

freq = rb_hash_aref(hash, i);

if (!RB_TYPE_P(freq, T_FIXNUM)) {

freq = INT2FIX(0);

}

freql = FIX2LONG(freq);

freq = LONG2FIX(freql+1);

memo->u3.cnt += 1;

rb_hash_aset(hash, i, freq);

return Qnil;

}

static VALUE

relative_frequencies_norm_i(RB_BLOCK_CALL_FUNC_ARGLIST(i, count))

{

VALUE freq;

long freql;

freq = RARRAY_AREF(i, 1);

freql = FIX2LONG(freq);

freq = DBL2NUM((double)freql / count);

RARRAY_ASET(i, 1, freq);

return Qnil;

}

/*

* call-seq:

* enum.relative_frequencies -> a_hash

*

* Calculates the relative frequency of each object appearing in <i>enum</i>.

* Returns a hash where the keys are objects from <i>enum</i> and the

* values are numbers between 0.0 and 1.0, indicating what proportion of

* the entries in <i>enum</i> contain the object.

*

* For example, the pair <code>"crow" => 0.1</code> means that one out of

* every ten entries in <i>enum</i> contains <code>"crow"</code>.

*

* The hash is sorted, with the most common objects first.

*

* %w[cat bird bird horse].relative_frequencies

* #=> {"bird" => 0.5, "horse" => 0.25, "cat" => 0.25}

*

*/

static VALUE

enum_relative_frequencies(VALUE obj)

{

VALUE hash, sorted;

NODE *memo;

double count;

hash = rb_hash_new();

memo = NEW_MEMO(hash, 0, 0);

rb_block_call(obj, id_each, 0, 0, relative_frequencies_i, (VALUE)memo);

count = (double)memo->u3.cnt;

sorted = rb_block_call(hash, rb_intern("sort_by"), 0, 0, frequencies_sort_by_i, 0);

rb_block_call(sorted, id_each, 0, 0, relative_frequencies_norm_i, count);

hash = rb_funcall(sorted, rb_intern("to_h"), 0);

OBJ_INFECT(hash, obj);

return hash;

}

static VALUE

rb_define_method(rb_mEnumerable, "frequencies", enum_frequencies, 0);

rb_define_method(rb_mEnumerable, "relative_frequencies", enum_relative_frequencies, 0);

def test_frequencies

h = { 1 => 2, 2 => 2, 3 => 1}

assert_equal(h, @obj.frequencies)

assert_equal([:c, 2], [:a, :b, :c, :c].frequencies.first)

end

def test_relative_frequencies

h = { 1 => 0.4, 2 => 0.4, 3 => 0.2}

assert_equal(h, @obj.relative_frequencies)

assert_equal([:c, 0.5], [:a, :b, :c, :c].relative_frequencies.first)

end