Matriz girada 180 grados

PorJosé A. Alonso 27-marzo-20193-abril-2019

Definir la función

   matrizGirada180 :: Matrix a -> Matrix a

1	matrizGirada180 :: Matrix a -> Matrix a

tal que (matrizGirada180 p) es la matriz obtenida girando 180 grados la matriz p. Por ejemplo,

   λ> fromList 4 3 [1..]
   (  1  2  3 )
   (  4  5  6 )
   (  7  8  9 )
   ( 10 11 12 )

   λ> matrizGirada180 (fromList 4 3 [1..])
   ( 12 11 10 )
   (  9  8  7 )
   (  6  5  4 )
   (  3  2  1 )

   λ> fromList 3 4 [1..]
   (  1  2  3  4 )
   (  5  6  7  8 )
   (  9 10 11 12 )

   λ> matrizGirada180 (fromList 3 4 [1..])
   ( 12 11 10  9 )
   (  8  7  6  5 )
   (  4  3  2  1 )

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λ> fromList 4 3 [1..]

( 1 2 3 )

( 4 5 6 )

( 7 8 9 )

( 10 11 12 )

λ> matrizGirada180 (fromList 4 3 [1..])

( 12 11 10 )

( 9 8 7 )

( 6 5 4 )

( 3 2 1 )

λ> fromList 3 4 [1..]

( 1 2 3 4 )

( 5 6 7 8 )

( 9 10 11 12 )

λ> matrizGirada180 (fromList 3 4 [1..])

( 12 11 10 9 )

( 8 7 6 5 )

( 4 3 2 1 )

Soluciones

import Data.Matrix ( Matrix
                   , (!)
                   , fromList
                   , fromLists
                   , matrix
                   , ncols
                   , nrows
                   , toLists
                   )

-- 1ª solución
matrizGirada180 :: Matrix a -> Matrix a
matrizGirada180 p = matrix m n f
  where m       = nrows p
        n       = ncols p
        f (i,j) = p!(m-i+1,n-j+1)

-- 2ª solución
matrizGirada180b :: Matrix a -> Matrix a
matrizGirada180b p =
  fromLists (reverse (map reverse (toLists p)))

-- 3ª solución
matrizGirada180c :: Matrix a -> Matrix a
matrizGirada180c =
  fromLists . reverse . map reverse . toLists

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import Data.Matrix ( Matrix

, (!)

, fromList

, fromLists

, matrix

, ncols

, nrows

, toLists

)

-- 1ª solución

matrizGirada180 :: Matrix a -> Matrix a

matrizGirada180 p = matrix m n f

where m = nrows p

n = ncols p

f (i,j) = p!(m-i+1,n-j+1)

-- 2ª solución

matrizGirada180b :: Matrix a -> Matrix a

matrizGirada180b p =

fromLists (reverse (map reverse (toLists p)))

-- 3ª solución

matrizGirada180c :: Matrix a -> Matrix a

matrizGirada180c =

fromLists . reverse . map reverse . toLists

Pensamiento

Bueno es recordar
las palabras viejas
que han de volver a sonar.

Antonio Machado

5 Comentarios

import Data.Matrix

matrizGirada180 :: Matrix a -> Matrix a
matrizGirada180 m = matrix a b f
  where (a,b) = (nrows m, ncols m)
        f (i,j) = m ! (a-i+1,b-j+1)

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import Data.Matrix

matrizGirada180 :: Matrix a -> Matrix a

matrizGirada180 m = matrix a b f

where (a,b) = (nrows m, ncols m)

f (i,j) = m ! (a-i+1,b-j+1)

frahidzam dice:

27-marzo-2019 a las 08:34

Solución en Python.

Python

import numpy as np def matrizGirada180 (m): return np.rot90 (np.rot90 (m))

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import numpy as np

def matrizGirada180 (m):
return np.rot90 (np.rot90 (m))

Responder
adogargon dice:

27-marzo-2019 a las 10:03

Haskell

import Data.Matrix matrizGirada180 :: Matrix a -> Matrix a matrizGirada180 = fromLists . reverse . map reverse . toLists

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import Data.Matrix

matrizGirada180 :: Matrix a -> Matrix a
matrizGirada180 = fromLists . reverse . map reverse . toLists

Responder
javmarcha1 dice:

27-marzo-2019 a las 11:43

Haskell

import Data.Matrix matrizGirada180 :: Matrix a -> Matrix a matrizGirada180 m = fromLists (reverse (map reverse (toLists m)))

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import Data.Matrix

matrizGirada180 :: Matrix a -> Matrix a
matrizGirada180 m = fromLists (reverse (map reverse (toLists m)))

Responder

import Data.Matrix

matrizGirada180 :: Matrix a -> Matrix a
matrizGirada180 h = aux ((fromLists . map reverse . toLists) h)
  where aux c = f c (nrows c) 1
        f v n x | div n 2 == x = switchRows x (n-x+1) v
                | otherwise    = f (switchRows x (n-x+1) v) n (x+1)

matrizGirada180' :: Matrix a -> Matrix a
matrizGirada180' h = aux ((fromLists . reverse . toLists) h)
  where aux c = f c (ncols c) 1
        f v n x | div n 2 == x = switchCols x (n-x+1) v
                | otherwise    = f (switchCols x (n-x+1) v) n (x+1)

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import Data.Matrix

matrizGirada180 :: Matrix a -> Matrix a

matrizGirada180 h = aux ((fromLists . map reverse . toLists) h)

where aux c = f c (nrows c) 1

f v n x | div n 2 == x = switchRows x (n-x+1) v

| otherwise = f (switchRows x (n-x+1) v) n (x+1)

matrizGirada180' :: Matrix a -> Matrix a

matrizGirada180' h = aux ((fromLists . reverse . toLists) h)

where aux c = f c (ncols c) 1

f v n x | div n 2 == x = switchCols x (n-x+1) v

| otherwise = f (switchCols x (n-x+1) v) n (x+1)

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