loadMatrix (based on wc)

2 files changed, 24 insertions, 3 deletions

diff --git a/lib/Data/Packed/Internal/Matrix.hs b/lib/Data/Packed/Internal/Matrix.hs
index 8a074a6..7678a12 100644
--- a/lib/Data/Packed/Internal/Matrix.hs
+++ b/lib/Data/Packed/Internal/Matrix.hs
@@ -351,7 +351,7 @@ fromComplex :: Vector (Complex Double) -> (Vector Double, Vector Double)
 fromComplex z = (r,i) where
     [r,i] = toColumns $ reshape 2 $ asReal z
 
--- | loads a matrix efficiently from formatted ASCII text file (the number of rows and columns must be known in advance).
+-- | loads a matrix from an ASCII file (the number of rows and columns must be known in advance).
 fromFile :: FilePath -> (Int,Int) -> IO (Matrix Double)
 fromFile filename (r,c) = do
     charname <- newCString filename
diff --git a/lib/Data/Packed/Matrix.hs b/lib/Data/Packed/Matrix.hs
index 0b50d8a..32eb991 100644
--- a/lib/Data/Packed/Matrix.hs
+++ b/lib/Data/Packed/Matrix.hs
@@ -29,7 +29,9 @@ module Data.Packed.Matrix (
     extractRows,
     ident, diag, diagRect, takeDiag,
     liftMatrix, liftMatrix2,
-    format, readMatrix, fromFile, fromArray2D
+    format,
+    loadMatrix, fromFile, fileDimensions,
+    readMatrix, fromArray2D
 ) where
 
 import Data.Packed.Internal
@@ -37,6 +39,7 @@ import qualified Data.Packed.ST as ST
 import Data.Packed.Vector
 import Data.List(transpose,intersperse)
 import Data.Array
+import System.Process(readProcess)
 
 -- | creates a matrix from a vertical list of matrices
 joinVert :: Element t => [Matrix t] -> Matrix t
@@ -227,10 +230,28 @@ dispC :: Int -> Matrix (Complex Double) -> IO ()
 dispC d m = disp m (shfc d)
 -}
 
--- | creates a matrix from a table of numbers.
+-- | reads a matrix from a string containing a table of numbers.
 readMatrix :: String -> Matrix Double
 readMatrix = fromLists . map (map read). map words . filter (not.null) . lines
 
+{- |  obtains the number of rows and columns in an ASCII data file
+      (provisionally using unix's wc).
+-}
+fileDimensions :: FilePath -> IO (Int,Int)
+fileDimensions fname = do
+    wcres <- readProcess "wc" ["-w",fname] ""
+    contents <- readFile fname
+    let tot = read . head . words $ wcres
+        c   = length . head . dropWhile null . map words . lines $ contents
+    if tot > 0
+        then return (tot `div` c, c)
+        else return (0,0)
+
+{- | loads a matrix from a formatted ASCII file.
+-}
+loadMatrix :: FilePath -> IO (Matrix Double)
+loadMatrix file = fromFile file =<< fileDimensions file
+
 -- | rearranges the rows of a matrix according to the order given in a list of integers. 
 extractRows :: Element t => [Int] -> Matrix t -> Matrix t
 extractRows l m = fromRows $ extract (toRows $ m) l