[Haskell-cafe] a sort of chunk

[PICCA Frederic-Emmanuel]

Hello,

I need to write some code in order to do some computations with stack of images coming from hdf5 files.
Each computation done per images is quite intensive, so I want to do this on multiple cores of my computer (24 in my case)

A stack of images  is composed of  a list of files. each file contain n images.
So I decided to proceed like this: 

create a data type which represent a chunk of this stack.

data Chunk = Chunk { filename :: FilePath
                               , from :: Int
                               , to :: Int
                               }


And indeed the full stack is [Chunk]

Now  since I have n core, I need to split the full stack in equivalent chunk of images.

Just for example. at the begining I have this image stack

30476 images
[Chunk "/nfs/ruche-sixs/sixs-soleil/com-sixs/2019/Run3/FeSCO_Cu111/sample2_ascan_omega_00077.nxs" 0 698,Chunk "/nfs/ruche-sixs/sixs-soleil/com-sixs/2019/Run3/FeSCO_Cu111/sample2_ascan_omega_00078.nxs" 0 1104,Chunk "/nfs/ruche-sixs/sixs-soleil/com-sixs/2019/Run3/FeSCO_Cu111/sample2_ascan_omega_00079.nxs" 0 1510,Chunk "/nfs/ruche-sixs/sixs-soleil/com-sixs/2019/Run3/FeSCO_Cu111/sample2_ascan_omega_00080.nxs" 0 1914,Chunk "/nfs/ruche-sixs/sixs-soleil/com-sixs/2019/Run3/FeSCO_Cu111/sample2_ascan_omega_00081.nxs" 0 2318,Chunk "/nfs/ruche-sixs/sixs-soleil/com-sixs/2019/Run3/FeSCO_Cu111/sample2_ascan_omega_00082.nxs" 0 2720,Chunk "/nfs/ruche-sixs/sixs-soleil/com-sixs/2019/Run3/FeSCO_Cu111/sample2_ascan_omega_00083.nxs" 0 2169,Chunk "/nfs/ruche-sixs/sixs-soleil/com-sixs/2019/Run3/FeSCO_Cu111/sample2_ascan_omega_00084.nxs" 0 2445,Chunk "/nfs/ruche-sixs/sixs-soleil/com-sixs/2019/Run3/FeSCO_Cu111/sample2_ascan_omega_00085.nxs" 0 2720,Chunk "/nfs/ruche-sixs/sixs-soleil/com-sixs/2019/Run3/FeSCO_Cu111/sample2_ascan_omega_00086.nxs" 0 490,Chunk "/nfs/ruche-sixs/sixs-soleil/com-sixs/2019/Run3/FeSCO_Cu111/sample2_ascan_omega_00087.nxs" 0 812,Chunk "/nfs/ruche-sixs/sixs-soleil/com-sixs/2019/Run3/FeSCO_Cu111/sample2_ascan_omega_00088.nxs" 0 1133,Chunk "/nfs/ruche-sixs/sixs-soleil/com-sixs/2019/Run3/FeSCO_Cu111/sample2_ascan_omega_00089.nxs" 0 1454,Chunk "/nfs/ruche-sixs/sixs-soleil/com-sixs/2019/Run3/FeSCO_Cu111/sample2_ascan_omega_00090.nxs" 0 1773,Chunk "/nfs/ruche-sixs/sixs-soleil/com-sixs/2019/Run3/FeSCO_Cu111/sample2_ascan_omega_00091.nxs" 0 2090,Chunk "/nfs/ruche-sixs/sixs-soleil/com-sixs/2019/Run3/FeSCO_Cu111/sample2_ascan_omega_00092.nxs" 0 2406,Chunk "/nfs/ruche-sixs/sixs-soleil/com-sixs/2019/Run3/FeSCO_Cu111/sample2_ascan_omega_00093.nxs" 0 2720]

so i need to write a function which do something like chunksOf

chunksOf :: Int -> [Chunk] -> [[Chunk]]

In this case I need to create chunk of 1325 images, so the finla result should be

[ [Chunk "/nfs/ruche-sixs/sixs-soleil/com-sixs/2019/Run3/FeSCO_Cu111/sample2_ascan_omega_00077.nxs" 0 698,Chunk "/nfs/ruche-sixs/sixs-soleil/com-sixs/2019/Run3/FeSCO_Cu111/sample2_ascan_omega_00078.nxs" 0 627]
, [Chunk "/nfs/ruche-sixs/sixs-soleil/com-sixs/2019/Run3/FeSCO_Cu111/sample2_ascan_omega_00078.nxs" 627 1104, ...]
...
]

I would like your help in order to give me advices or help me find information whcih can help me implement this chunksOf method.

thanks for your help.

Frederic