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113 lines
3.6 KiB
Haskell
113 lines
3.6 KiB
Haskell
-- Copyright 2016 TensorFlow authors.
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--
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-- Licensed under the Apache License, Version 2.0 (the "License");
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-- you may not use this file except in compliance with the License.
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-- You may obtain a copy of the License at
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--
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-- http://www.apache.org/licenses/LICENSE-2.0
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--
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-- Unless required by applicable law or agreed to in writing, software
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-- distributed under the License is distributed on an "AS IS" BASIS,
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-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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-- See the License for the specific language governing permissions and
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-- limitations under the License.
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{-# LANGUAGE LambdaCase #-}
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-- | Downloads the MNIST data set and packages them as data files.
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module Main where
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import Control.Monad (when)
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import Data.Maybe (fromMaybe)
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import Distribution.PackageDescription
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( GenericPackageDescription(packageDescription)
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, dataDir
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)
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import Distribution.Simple
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( UserHooks(..)
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, defaultMainWithHooks
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, simpleUserHooks
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)
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import System.IO (hPutStrLn, stderr)
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import System.FilePath ((</>))
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import System.Directory (doesFileExist)
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import qualified Crypto.Hash as Hash
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import qualified Data.ByteString.Lazy as B
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import qualified Network.HTTP as HTTP
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import qualified Network.URI as URI
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main :: IO ()
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main = defaultMainWithHooks downloadingDataFiles
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downloadingDataFiles :: UserHooks
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downloadingDataFiles = hooks
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{ confHook = \gh@(g, _) c -> downloadFiles g >> confHook hooks gh c
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}
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where
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hooks = simpleUserHooks
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downloadFiles :: GenericPackageDescription -> IO ()
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downloadFiles g = do
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let dir = dataDir (packageDescription g)
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mapM_ (maybeDownload dir) fileInfos
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maybeDownload :: FilePath -> (String, String) -> IO ()
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maybeDownload dataDir (basename, sha256) = do
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let filePath = dataDir </> basename
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exists <- doesFileExist filePath
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when (not exists) $ do
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let url = urlPrefix ++ basename
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hPutStrLn stderr ("Downloading " ++ url)
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httpDownload url filePath
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verify filePath sha256
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httpDownload :: String -> FilePath -> IO ()
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httpDownload url outFile = do
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let uri = fromMaybe
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(error ("Can't be: invalid URI " ++ url))
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(URI.parseURI url)
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result <- HTTP.simpleHTTP (HTTP.defaultGETRequest_ uri)
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HTTP.getResponseCode result >>= \case
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(2, 0, 0) -> HTTP.getResponseBody result >>= B.writeFile outFile
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s -> error ( "Failed to download " ++ url ++ " error code " ++ show s
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++ helpfulMessage
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)
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verify :: FilePath -> String -> IO ()
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verify filePath hash = do
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let sha256 = Hash.hashlazy :: B.ByteString -> Hash.Digest Hash.SHA256
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computed <- show . sha256 <$> B.readFile filePath
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when (hash /= computed) $
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error ( "Incorrect checksum for " ++ filePath
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++ "\nexpected " ++ hash
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++ "\ncomputed " ++ computed
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++ helpfulMessage
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)
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urlPrefix = "http://yann.lecun.com/exdb/mnist/"
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-- | File names relative to 'urlPrefix' and their sha256.
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fileInfos = [
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( "train-images-idx3-ubyte.gz"
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, "440fcabf73cc546fa21475e81ea370265605f56be210a4024d2ca8f203523609"
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)
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,
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( "train-labels-idx1-ubyte.gz"
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, "3552534a0a558bbed6aed32b30c495cca23d567ec52cac8be1a0730e8010255c"
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)
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,
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( "t10k-images-idx3-ubyte.gz"
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, "8d422c7b0a1c1c79245a5bcf07fe86e33eeafee792b84584aec276f5a2dbc4e6"
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)
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,
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( "t10k-labels-idx1-ubyte.gz"
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, "f7ae60f92e00ec6debd23a6088c31dbd2371eca3ffa0defaefb259924204aec6"
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)
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]
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helpfulMessage =
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unlines
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( ""
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: ""
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: "Please download the following URLs manually and put them in data/"
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: [ urlPrefix ++ h | (h, _) <- fileInfos ]
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)
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