centroids

ChangeLog.md

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+# Changelog for centwo
+
+## Unreleased changes

LICENSE

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+Copyright Author name here (c) 2020
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of Author name here nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

README.md

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+# centwo

Setup.hs

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+import Distribution.Simple
+main = defaultMain

app/Main.hs

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+module Main where
+
+import Lib
+import qualified Figs
+import qualified Graphics.Gloss as G
+
+main :: IO ()
+main = solve Figs.owlcation
+
+solve figure = 
+  print figure
+  >> print (centroid figure)
+  >> G.display (G.InWindow "Centroid Visualization" (200, 200) (10, 10)) G.black (toPicture figure)
+
+-- the 'figure' value here shadows that global one
+toPicture :: Compound -> G.Picture
+toPicture figure@(Compound figures) = G.pictures $ map toPicture' figures ++ [centroid']
+  where toPicture' (Figure geometry (Location dx dy) axis swapped negation) =
+          color negation 
+          . G.translate (realToFrac dx) (realToFrac dy)
+          . swap swapped
+          . mirror axis
+          . shape $ geometry
+
+          where swap NS = id
+                swap S = G.rotate 90
+
+                mirror N = G.scale 1 1
+                mirror X = G.scale 1 (-1)
+                mirror Y = G.scale (-1) 1
+                mirror XY = G.scale (-1) (-1)
+
+                color Positive = G.color G.blue
+                color Negative = G.color G.red
+
+        centroid' = let dx = getX $ centroid figure
+                        dy = getY $ centroid figure
+                    in G.translate dx dy . G.color G.red $ G.circleSolid 5
+
+          where getX (Location x _) = realToFrac x
+                getY (Location _ y) = realToFrac y
+
+shape :: Geometry -> G.Picture
+shape (Rectangle w h) = rectangle (realToFrac w) (realToFrac h)
+shape (Triangle b h) = rightTriangle (realToFrac b) (realToFrac h)
+shape (Semicircle r) = semicircle (realToFrac r)
+
+rightTriangle :: Float -> Float -> G.Picture
+rightTriangle b h = G.polygon [(0, 0), (b, 0), (0, h)]
+
+-- defining our own rectangle so that the global origin is on the lower right
+-- the gloss builtin rectangle is centered on the global origin
+rectangle :: Float -> Float -> G.Picture
+rectangle w h = G.polygon [(0, 0), (w, 0), (w, h), (0, h)]
+
+semicircle :: Float -> G.Picture
+semicircle r = G.arcSolid 0 180 r

package.yaml

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+name:                centwo
+version:             0.1.0.0
+github:              "githubuser/centwo"
+license:             BSD3
+author:              "Author name here"
+maintainer:          "example@example.com"
+copyright:           "2020 Author name here"
+
+extra-source-files:
+- README.md
+- ChangeLog.md
+
+# Metadata used when publishing your package
+# synopsis:            Short description of your package
+# category:            Web
+
+# To avoid duplicated efforts in documentation and dealing with the
+# complications of embedding Haddock markup inside cabal files, it is
+# common to point users to the README.md file.
+description:         Please see the README on GitHub at <https://github.com/githubuser/centwo#readme>
+
+dependencies:
+- base >= 4.7 && < 5
+- gloss
+
+library:
+  source-dirs: src
+
+executables:
+  centwo-exe:
+    main:                Main.hs
+    source-dirs:         app
+    ghc-options:
+    - -threaded
+    - -rtsopts
+    - -with-rtsopts=-N
+    dependencies:
+    - centwo
+
+tests:
+  centwo-test:
+    main:                Spec.hs
+    source-dirs:         test
+    ghc-options:
+    - -threaded
+    - -rtsopts
+    - -with-rtsopts=-N
+    dependencies:
+    - centwo

src/Figs.hs

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+module Figs
+    ( question3
+    , owlcation
+    ) where
+
+import Lib
+
+question3 = Compound [ Figure (Rectangle 2 2) (Location 0 0) N NS Positive
+                     , Figure (Rectangle 0.75 0.5) (Location 0.625 0) N NS Negative
+                     , Figure (Semicircle 0.625) (Location 1 2) X NS Negative ]
+
+owlcation = Compound [ Figure (Rectangle 300 250) (Location (-150) 0) N NS Positive
+                     , Figure (Triangle 120 120) (Location 150 250) XY NS Negative
+                     , Figure (Semicircle 100) (Location (-150) 135) N S Negative ]

src/Lib.hs

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+module Lib
+    ( Geometry ( Rectangle, Triangle, Semicircle )
+    , Location ( Location )
+    , Mirror ( N, X, Y, XY )
+    , Swap ( NS, S )
+    , Negation ( Positive, Negative )
+    , Figure ( Figure )
+    , Centroid ( area, xb, yb )
+    , Compound ( Compound )
+    , centroid
+    ) where
+
+data Geometry = Rectangle Double Double -- width x height
+              | Triangle Double Double  -- base x height
+              | Semicircle Double       -- radius
+              deriving Show
+
+data Location = Location Double Double deriving Show -- x, y
+data Mirror = N | X | Y | XY deriving Show
+data Swap = NS | S deriving Show
+data Negation = Positive | Negative deriving Show
+data Figure = Figure Geometry Location Mirror Swap Negation deriving Show
+
+newtype Compound = Compound [Figure] deriving Show
+
+class Centroid a where
+  area :: a -> Double
+  xb :: a -> Double
+  yb :: a -> Double
+
+instance Centroid Geometry where
+  area (Rectangle w h) = w * h
+  area (Triangle b h) = b * h / 2
+  area (Semicircle r) = pi * r ^ 2 / 2
+
+  xb (Rectangle w _) = w / 2
+  xb (Triangle b _) = b / 3
+  xb (Semicircle r) = 0
+
+  yb (Rectangle _ h) = h / 2
+  yb (Triangle _ h) = h / 3
+  yb (Semicircle r) = 4 * r / (3 * pi)
+
+-- xb' / yb' swap the actual xbs and ybs
+-- mirror reflects across the axis, origin stays (0, 0)
+-- negate' negates an area depending on whether its positive or negative space
+
+instance Centroid Figure where
+  area (Figure geometry _ _ _ negation) = negate' negation $ area geometry
+    where negate' Positive = id
+          negate' Negative = negate
+
+  xb (Figure geometry (Location dx _) axis swapped _) =
+    (+ dx) . mirror axis . xb' swapped $ geometry
+
+    where mirror Y = negate
+          mirror XY = negate
+          mirror _ = id
+
+          xb' NS = xb
+          xb' S = yb
+
+  yb (Figure geometry (Location _ dy) axis swapped _) =
+    (+ dy) . mirror axis . yb' swapped $ geometry
+
+    where mirror X = negate
+          mirror XY = negate
+          mirror _ = id
+
+          yb' NS = yb
+          yb' S = xb
+
+centroid :: Compound -> Location
+centroid (Compound figures) = Location (dist xb) (dist yb)
+  where dist f = (sum $ map (\figure -> area figure * f figure) figures)
+                 / (sum $ map area figures)

stack.yaml

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+# This file was automatically generated by 'stack init'
+#
+# Some commonly used options have been documented as comments in this file.
+# For advanced use and comprehensive documentation of the format, please see:
+# https://docs.haskellstack.org/en/stable/yaml_configuration/
+
+# Resolver to choose a 'specific' stackage snapshot or a compiler version.
+# A snapshot resolver dictates the compiler version and the set of packages
+# to be used for project dependencies. For example:
+#
+# resolver: lts-3.5
+# resolver: nightly-2015-09-21
+# resolver: ghc-7.10.2
+#
+# The location of a snapshot can be provided as a file or url. Stack assumes
+# a snapshot provided as a file might change, whereas a url resource does not.
+#
+# resolver: ./custom-snapshot.yaml
+# resolver: https://example.com/snapshots/2018-01-01.yaml
+resolver: lts-14.22
+
+# User packages to be built.
+# Various formats can be used as shown in the example below.
+#
+# packages:
+# - some-directory
+# - https://example.com/foo/bar/baz-0.0.2.tar.gz
+#   subdirs:
+#   - auto-update
+#   - wai
+packages:
+- .
+# Dependency packages to be pulled from upstream that are not in the resolver.
+# These entries can reference officially published versions as well as
+# forks / in-progress versions pinned to a git hash. For example:
+#
+# extra-deps:
+# - acme-missiles-0.3
+# - git: https://github.com/commercialhaskell/stack.git
+#   commit: e7b331f14bcffb8367cd58fbfc8b40ec7642100a
+#
+# extra-deps: []
+
+# Override default flag values for local packages and extra-deps
+# flags: {}
+
+# Extra package databases containing global packages
+# extra-package-dbs: []
+
+# Control whether we use the GHC we find on the path
+# system-ghc: true
+#
+# Require a specific version of stack, using version ranges
+# require-stack-version: -any # Default
+# require-stack-version: ">=2.1"
+#
+# Override the architecture used by stack, especially useful on Windows
+# arch: i386
+# arch: x86_64
+#
+# Extra directories used by stack for building
+# extra-include-dirs: [/path/to/dir]
+# extra-lib-dirs: [/path/to/dir]
+#
+# Allow a newer minor version of GHC than the snapshot specifies
+# compiler-check: newer-minor

stack.yaml.lock

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+# This file was autogenerated by Stack.
+# You should not edit this file by hand.
+# For more information, please see the documentation at:
+#   https://docs.haskellstack.org/en/stable/lock_files
+
+packages: []
+snapshots:
+- completed:
+    size: 524164
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/14/22.yaml
+    sha256: 7ad8f33179b32d204165a3a662c6269464a47a7e65a30abc38d01b5a38ec42c0
+  original: lts-14.22

test/Spec.hs

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+main :: IO ()
+main = putStrLn "Test suite not yet implemented"