[Haskell-cafe] hmatrix-labeled: request for comments

Nikita Karetnikov nikita at karetnikov.org
Wed Feb 19 19:06:42 UTC 2014

I like how easy it is to import data in R and Octave.  (See [1] for a
typical workflow.)  Since I couldn’t find any matching library on
Hackage, I cooked up my own [2] in a couple of days.

Here’s an example.  Let’s start by creating a poorly formatted dataset:

$ cat > test.txt
   		         One         Two Longish   Four
     Foo  1       -2		3.0     4.0
Looooooong  5.0   6.0   -72.0		      8.0
	Baz 41.0 4.2324234e7  43.0 1.111111144E-12

Then we parse it with ‘readFile’, mangle the data a bit, and display in

λ> import qualified Data.Packed.LMatrix.IO as L
λ> import qualified Data.Packed.LMatrix as L
λ> do m <- L.readFile "test.txt"; return . L.trans . L.reverseRows $ L.map (+1) m
                       Baz Looooooong  Foo
    One               42.0        6.0  2.0
    Two        4.2324235e7        7.0 -1.0
Longish               44.0      -71.0  4.0
   Four 1.0000000000011111        9.0  5.0

Now I’m wondering how to make it better.  I’m planning to add the
documentation, augment the parser to accept CSV, and maybe support other
matrix libraries.  What’s missing?  Would you like to see it on Hackage?
And if not, why?

[1] http://astrostatistics.psu.edu/su09/lecturenotes/pca.html
[2] https://gitorious.org/hmatrix-labeled
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