{"id":8502,"date":"2024-02-24T06:00:08","date_gmt":"2024-02-24T04:00:08","guid":{"rendered":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/?p=8502"},"modified":"2024-02-27T19:12:52","modified_gmt":"2024-02-27T17:12:52","slug":"24-feb-24","status":"publish","type":"post","link":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/24-feb-24\/","title":{"rendered":"Duplicaci\u00f3n de cada elemento"},"content":{"rendered":"<p>Definir la funci\u00f3n<\/p>\n<pre lang=\"text\">\n   duplicaElementos :: [a] -> [a]\n<\/pre>\n<p>tal que (duplicaElementos xs) es la lista obtenida duplicando cada elemento de xs. Por ejemplo,<\/p>\n<pre lang=\"text\">\n   duplicaElementos [3,2,5]    ==  [3,3,2,2,5,5]\n   duplicaElementos \"Haskell\"  ==  \"HHaasskkeellll\"\n<\/pre>\n<p><!--more--><\/p>\n<p><a name=\"haskell\"><\/a><\/p>\n<h2>1. Soluciones en Haskell<\/h2>\n<pre lang=\"haskell\">\nmodule Duplicacion_de_cada_elemento where\n\nimport Test.Hspec (Spec, describe, hspec, it, shouldBe)\nimport Test.QuickCheck\n\n--  1\u00aa soluci\u00f3n\nduplicaElementos1 :: [a] -> [a]\nduplicaElementos1 []     = []\nduplicaElementos1 (x:xs) = x : x : duplicaElementos1 xs\n\n-- 2 soluci\u00f3n\nduplicaElementos2 :: [a] -> [a]\nduplicaElementos2 = foldr (\\x ys -> x:x:ys) []\n\n-- 3\u00aa soluci\u00f3n\nduplicaElementos3 :: [a] -> [a]\nduplicaElementos3 xs = concat [[x,x] | x <- xs]\n\n-- 4\u00aa soluci\u00f3n\nduplicaElementos4 :: [a] -> [a]\nduplicaElementos4 xs = concat (map (replicate 2) xs)\n\n-- 5\u00aa soluci\u00f3n\nduplicaElementos5 :: [a] -> [a]\nduplicaElementos5 = concatMap (replicate 2)\n\n-- 6\u00aa soluci\u00f3n\nduplicaElementos6 :: [a] -> [a]\nduplicaElementos6 = (>>= replicate 2)\n\n-- Verificaci\u00f3n\n-- ============\n\nverifica :: IO ()\nverifica = hspec spec\n\nspecG :: ([Int] -> [Int]) -> Spec\nspecG duplicaElementos = do\n  it \"e1\" $\n    duplicaElementos [3,2,5] `shouldBe` [3,3,2,2,5,5]\n\nspec :: Spec\nspec = do\n  describe \"def. 1\" $ specG duplicaElementos1\n  describe \"def. 2\" $ specG duplicaElementos2\n  describe \"def. 3\" $ specG duplicaElementos3\n  describe \"def. 4\" $ specG duplicaElementos4\n  describe \"def. 5\" $ specG duplicaElementos5\n  describe \"def. 6\" $ specG duplicaElementos6\n\n-- La verificaci\u00f3n es\n--    \u03bb> verifica\n--\n--    6 examples, 0 failures\n\n-- Equivalencia de las definiciones\n-- ================================\n\n-- La propiedad es\nprop_duplicaElementos :: [Int] -> Bool\nprop_duplicaElementos xs =\n  all (== duplicaElementos1 xs)\n      [f xs | f <- [duplicaElementos2,\n                    duplicaElementos3,\n                    duplicaElementos4,\n                    duplicaElementos5,\n                    duplicaElementos6]]\n\nverifica_duplicaElementos :: IO ()\nverifica_duplicaElementos = quickCheck prop_duplicaElementos\n\n-- La comprobaci\u00f3n es\n--    \u03bb> verifica_duplicaElementos\n--    +++ OK, passed 100 tests.\n<\/pre>\n<p><a name=\"python\"><\/a><\/p>\n<h2>2. Soluciones en Python<\/h2>\n<pre lang=\"python\">\nfrom functools import reduce\nfrom typing import TypeVar\n\nfrom hypothesis import given\nfrom hypothesis import strategies as st\n\nA = TypeVar('A')\n\n# 1\u00aa soluci\u00f3n\n# ===========\n\ndef duplicaElementos1(ys: list[A]) -> list[A]:\n    if not ys:\n        return []\n    x, *xs = ys\n    return [x, x] + duplicaElementos1(xs)\n\n# 2 soluci\u00f3n\n# ===========\n\ndef duplicaElementos2(xs: list[A]) -> list[A]:\n    return reduce(lambda ys, x: ys + [x, x], xs, [])\n\n# 3\u00aa soluci\u00f3n\n# ===========\n\ndef duplicaElementos3(xs: list[A]) -> list[A]:\n    return [x for x in xs for _ in range(2)]\n\n# 4\u00aa soluci\u00f3n\n# ===========\n\ndef duplicaElementos4(xs: list[A]) -> list[A]:\n    ys = []\n    for x in xs:\n        ys.append(x)\n        ys.append(x)\n    return ys\n\n# Verificaci\u00f3n\n# ============\n\ndef test_duplicaElementos() -> None:\n    for duplicaElementos in [duplicaElementos1, duplicaElementos2,\n                             duplicaElementos3, duplicaElementos4]:\n        assert duplicaElementos([3,2,5]) == [3,3,2,2,5,5]\n    print(\"Verificado\")\n\n# La verificaci\u00f3n es\n#    >>> test_duplicaElementos()\n#    Verificado\n\n# Equivalencia de las definiciones\n# ================================\n\n# La propiedad es\n@given(st.lists(st.integers()))\ndef test_duplicaElementos_equiv(xs: list[int]) -> None:\n    r = duplicaElementos1(xs)\n    assert duplicaElementos2(xs) == r\n    assert duplicaElementos3(xs) == r\n    assert duplicaElementos4(xs) == r\n\n# La comprobaci\u00f3n es\n#    >>> test_duplicaElementos_equiv()\n#    >>>\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Definir la funci\u00f3n duplicaElementos :: [a] -> [a] tal que (duplicaElementos xs) es la lista obtenida duplicando cada elemento de xs. Por ejemplo, duplicaElementos [3,2,5] == [3,3,2,2,5,5] duplicaElementos \u00abHaskell\u00bb == \u00abHHaasskkeellll\u00bb<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_kad_post_transparent":"default","_kad_post_title":"default","_kad_post_layout":"default","_kad_post_sidebar_id":"","_kad_post_content_style":"default","_kad_post_vertical_padding":"default","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"footnotes":"","_jetpack_memberships_contains_paid_content":false},"categories":[581],"tags":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/8502"}],"collection":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/comments?post=8502"}],"version-history":[{"count":1,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/8502\/revisions"}],"predecessor-version":[{"id":8503,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/8502\/revisions\/8503"}],"wp:attachment":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/media?parent=8502"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/categories?post=8502"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/tags?post=8502"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}