From 3815bc25f62124063e02af83fe3c907336dc86f5 Mon Sep 17 00:00:00 2001
From: Alberto Ruiz <aruiz@um.es>
Date: Fri, 28 Sep 2007 12:25:56 +0000
Subject: algorithms interface reorganized

---
 lib/Data/Packed/Internal/Matrix.hs | 12 ++++++++++++
 lib/Data/Packed/Internal/aux.h     |  2 ++
 lib/Data/Packed/Matrix.hs          |  8 +++++++-
 3 files changed, 21 insertions(+), 1 deletion(-)

(limited to 'lib/Data/Packed')

diff --git a/lib/Data/Packed/Internal/Matrix.hs b/lib/Data/Packed/Internal/Matrix.hs
index 63ebddf..e76500b 100644
--- a/lib/Data/Packed/Internal/Matrix.hs
+++ b/lib/Data/Packed/Internal/Matrix.hs
@@ -24,6 +24,8 @@ import Complex
 import Control.Monad(when)
 import Data.List(transpose,intersperse)
 import Data.Maybe(fromJust)
+import Foreign.C.String
+import Foreign.C.Types
 
 -----------------------------------------------------------------
 
@@ -371,6 +373,16 @@ fromComplex z = (r,i) where
 comp :: Vector Double -> Vector (Complex Double)
 comp v = toComplex (v,constant 0 (dim v))
 
+-- | loads a matrix efficiently from formatted ASCII text 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
+    res <- createMatrix RowMajor r c
+    c_gslReadMatrix charname // mat dat res // check "gslReadMatrix" []
+    --free charname  -- TO DO: free the auxiliary CString
+    return res
+foreign import ccall "aux.h matrix_fscanf" c_gslReadMatrix:: Ptr CChar -> TM
+
 -------------------------------------------------------------------------
 
 -- Generic definitions
diff --git a/lib/Data/Packed/Internal/aux.h b/lib/Data/Packed/Internal/aux.h
index 83111e5..73334e3 100644
--- a/lib/Data/Packed/Internal/aux.h
+++ b/lib/Data/Packed/Internal/aux.h
@@ -26,3 +26,5 @@ int diagR(KRVEC(d),RMAT(r));
 int diagC(KCVEC(d),CMAT(r));
 
 const char * gsl_strerror (const int gsl_errno);
+
+int matrix_fscanf(char*filename, RMAT(a));
diff --git a/lib/Data/Packed/Matrix.hs b/lib/Data/Packed/Matrix.hs
index 404fde7..2b93348 100644
--- a/lib/Data/Packed/Matrix.hs
+++ b/lib/Data/Packed/Matrix.hs
@@ -25,9 +25,10 @@ module Data.Packed.Matrix (
     fromBlocks,
     flipud, fliprl,
     subMatrix, takeRows, dropRows, takeColumns, dropColumns,
+    extractRows,
     ident, diag, diagRect, takeDiag,
     liftMatrix, liftMatrix2,
-    format, dispR, readMatrix, fromArray2D
+    format, dispR, readMatrix, fromFile, fromArray2D
 ) where
 
 import Data.Packed.Internal
@@ -209,3 +210,8 @@ dispC d m = disp m (shfc d)
 -- | creates a matrix from a table of numbers.
 readMatrix :: String -> Matrix Double
 readMatrix = fromLists . map (map read). map words . filter (not.null) . lines
+
+-- | rearranges the rows of a matrix according to the order given in a list of integers. 
+extractRows :: Field t => [Int] -> Matrix t -> Matrix t
+extractRows l m = fromRows $ extract (toRows $ m) l
+    where extract l is = [l!!i |i<-is]
-- 
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