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dataframeindexingjuliaany

Understanding with julia dataframes indexing

I am learning julia and i've just found this line:

if(any(mach_df[start_slot:(start_slot + task_setup_time), Symbol(machine)].== 0))

What does it mean?, I know any is a function that returns true if every value of the parameter is true but I just can't understand what is inside the brakets.

Regards

Solution

  • Let us work inside out:

    • mach_df[start_slot:(start_slot + task_setup_time), Symbol(machine)] selects you rows from the range start_slot:(start_slot + task_setup_time) and column named Symbol(machine) (Symbol is most likely not needed, but I would need to see your source code to tell you exacly); as a result you get a vector.
    • mach_df[start_slot:(start_slot + task_setup_time), Symbol(machine)] .== 0 gives you another vector that has true if the value in the LHS vector is 0.
    • the any part will return true if any of the values in the vector produced above is true.

    A more advanced (and efficient) way to write it would be:

    any(==(0), @view mach_df[start_slot:(start_slot + task_setup_time), Symbol(machine)])

    but I am not sure if you need performance in your use case.