8000 [ruby/matrix] Add `Matrix#rotate_entries` [#19] · ruby/ruby@e34f51f · GitHub
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[ruby/matrix] Add Matrix#rotate_entries [#19]
Co-authored-by: Marc-André Lafortune <github@marc-andre.ca>
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‎lib/matrix.rb

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@@ -1458,6 +1458,35 @@ def rank_e
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rank
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end
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#
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# Returns a new matrix with rotated elements.
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# The argument specifies the rotation (defaults to `:clockwise`):
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# * :clockwise, 1, -3, etc.: "turn right" - first row becomes last column
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# * :half_turn, 2, -2, etc.: first row becomes last row, elements in reverse order
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# * :counter_clockwise, -1, 3: "turn left" - first row becomes first column
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# (but with elements in reverse order)
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#
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# m = Matrix[ [1, 2], [3, 4] ]
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# r = m.rotate_entries(:clockwise)
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# # => Matrix[[3, 1], [4, 2]]
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#
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def rotate_entries(rotation = :clockwise)
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rotation %= 4 if rotation.respond_to? :to_int
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case rotation
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when 0
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dup
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when 1, :clockwise
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new_matrix @rows.transpose.each(&:reverse!), row_count
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when 2, :half_turn
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new_matrix @rows.map(&:reverse).reverse!, column_count
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when 3, :counter_clockwise
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new_matrix @rows.transpose.reverse!, row_count
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else
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raise ArgumentError, "expected #{rotation.inspect} to be one of :clockwise, :counter_clockwise, :half_turn or an integer"
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end
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end
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# Returns a matrix with entries rounded to the given precision
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# (see Float#round)
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#

‎test/matrix/test_matrix.rb

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@@ -829,4 +829,60 @@ def test_ractor
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assert_same obj1, obj2
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RUBY
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end
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def test_rotate_with_symbol
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assert_equal(Matrix[[4, 1], [5, 2], [6, 3]], @m1.rotate_entries)
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assert_equal(@m1.rotate_entries, @m1.rotate_entries(:clockwise))
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assert_equal(Matrix[[4, 1], [5, 2], [6, 3]],
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@m1.rotate_entries(:clockwise))
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assert_equal(Matrix[[3, 6], [2, 5], [1, 4]],
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@m1.rotate_entries(:counter_clockwise))
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assert_equal(Matrix[[6, 5, 4], [3, 2, 1]],
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@m1.rotate_entries(:half_turn))
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assert_equal(Matrix[[6, 5, 4], [3, 2, 1]],
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@m1.rotate_entries(:half_turn))
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assert_equal(Matrix.empty(0,2),
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@e1.rotate_entries(:clockwise))
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assert_equal(Matrix.empty(0,2),
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@e1.rotate_entries(:counter_clockwise))
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assert_equal(Matrix.empty(2,0),
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@e1.rotate_entries(:half_turn))
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assert_equal(Matrix.empty(0,3),
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@e2.rotate_entries(:half_turn))
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end
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def test_rotate_with_numeric
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assert_equal(Matrix[[4, 1], [5, 2], [6, 3]],
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@m1.rotate_entries(1))
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assert_equal(@m2.rotate_entries(:half_turn),
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@m2.rotate_entries(2))
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assert_equal(@m2.rotate_entries(:half_turn),
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@m1.rotate_entries(2))
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assert_equal(@m1.rotate_entries(:counter_clockwise),
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@m1.rotate_entries(3))
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assert_equal(@m1,
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@m1.rotate_entries(4))
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assert_equal(@m1,
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@m1.rotate_entries(4))
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assert_not_same(@m1,
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@m1.rotate_entries(4))
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assert_equal(@m1.rotate_entries(:clockwise),
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@m1.rotate_entries(5))
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assert_equal(Matrix.empty(0,2),
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@e1.rotate_entries(1))
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assert_equal(@e2,
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@e2.rotate_entries(2))
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assert_equal(@e2.rotate_entries(1),
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@e2.rotate_entries(3))
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assert_equal(@e2.rotate_entries(:counter_clockwise),
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@e2.rotate_entries(-1))
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assert_equal(@m1.rotate_entries(:counter_clockwise),
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@m1.rotate_entries(-1))
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assert_equal(Matrix[[6, 5, 4], [3, 2, 1]],
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@m1.rotate_entries(-2))
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assert_equal(@m1,
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@m1.rotate_entries(-4))
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assert_equal(@m1.rotate_entries(-1),
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@m1.rotate_entries(-5))
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end
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end

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