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    I just played with the Ocaml code a bit and got the run time halved. The performance hit comes from using a regex to split the string rather than just splitting it. The Python version uses just string splitting.

    I generated a CSV with:

    awk 'BEGIN { while (count++<30000000)  print rand()","(rand()*10)","(rand()*100) }' > /tmp/data.csv
    

    I moved the Ocaml code over to Core in order to have access to String.split, which just splits on a character instead of a regexp, which is pretty expensive.

    The new code is here: https://gist.github.com/orbitz/05afcda28a33f784d2fe

    Original:

    $ ocamlfind ocamlopt -thread -package core,str -linkpkg -o sum-ocaml foo.ml
    $ time ./sum-ocaml data.csv 
    15000332.2443,150006471.834,1500135734.85
    
    real    1m0.173s
    user    0m57.158s
    sys 0m2.403s
    

    Modified:

    $ time ./sum-ocaml data.csv 
    15000332.2443,150006471.834,1500135734.85
    
    real    0m26.482s
    user    0m25.351s
    sys 0m0.912s
    

    And as comparison, the Python version on my system with my file:

    $ time python3 foo.py data.csv 
    15000332.24433928,150006471.83433944,1500135734.846217
    
    real    1m58.709s
    user    1m57.410s
    sys 0m0.796s
    
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      Well done. That’s more like what I would expect. Thanks!

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      I’m surprised Python is so fast and OCaml isn’t even faster than it is!

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        Looks like the performance closeness was due to apples and oranges. Changing the Ocaml code to a split function puts the Ocaml a more expected bit faster than the Python (on my system at least).

        https://lobste.rs/s/uk2o1q/four_mls_and_a_python/comments/64raes#c_64raes

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          Hrm? The Ocaml one was 3 seconds faster.

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          By skimming through the python code I don’t know what this code is expected to do. I only guess it is not very pythonic (for example it doesn’t use the built in csv module and does many things strangely)