Attoparsec parser for the NIST Matrix Market format [0].
The library also contains functions for serializing matrix data to text file.
The module Data.Matrix.MatrixMarket exports the user interface:
readMatrix :: FilePath -> IO (Matrix S.Scientific)
readArray :: FilePath -> IO (Array S.Scientific)
writeMatrix :: Show a => FilePath -> Matrix a -> IO ()
writeArray :: Show a => FilePath -> Array a -> IO ()
The first two functions contain the parsing logic, and make use of scientific for parsing numerical data in scientific notation.
As of version 0.1.1 there are also intermediate functions @readMatrix'@, @readArray'@, @writeMatrix'@ and @writeArray'@ that do not touch the filesystem but (de-)serialize from/to lazy ByteString.
We follow the MatrixMarket format definitions, by which a "Matrix" is sparse and stored in coordinate format (row, column, entry), whereas an "Array" is a dense grid of numbers, stored in column-oriented form. Algebraic vectors, such as the right-hand sides of equation systems, are stored as n-by-1 Arrays.
test/LibSpec.hs contains a simple read/write/read sanity test for the included Matrix Marked data files (fidapm05.mtx and fidapm05_rhs1.mtx):
m0 <- readMatrix fname -- load original
writeMatrix ftemp m0 -- save as temp
m1 <- readMatrix ftemp -- load temp
m0 `shouldBe` m1 -- compare temp with original