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Thread: Logic problem

  1. #1
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    Default Logic problem

    I am stuck on a logic problem.

    I have the following struct:
    Qt Code:
    1. struct MeasurementData
    2. {
    3. bool complete = false;
    4. std::bitset<3> mode;
    5. std::bitset<12> frame_counter;
    6. std::bitset<16> expo_time;
    7. std::bitset<16> expo_time_max;
    8. std::bitset<24> ntc_val0_ref_2_4V;
    9. std::bitset<24> ntc_val0_ref_2_1V;
    10. std::bitset<24> ntc_val0_temp_2_4V;
    11. std::bitset<24> ntc_val0_temp_2_1V;
    12. };
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    Where the field frame_counter is a progressive number incremented after each measurement (starting from value 0).
    To fill in the fields of the structure I analyze an input file where each row contains the values that I have to insert in the structure.
    So I create a vector of structures and I create a new struct each time I parse a new row

    Qt Code:
    1. std::vector<MeasurementData> frames;
    2. std::string line;
    3. while (std::getline(input, line))
    4. {
    5. processLine(line, frames); // <- Here I create a new struct instance and add it to the vector
    6. }
    7. input.close();
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    My need is to find the missing frame_counter values when processing the corresponding file line

    For example:
    In my file I have 48 rows, this implies the creation of 48 struct instances and the frame_counter should start at 0 and end at 47 but in my case I have 3 missing measurement

    frame_counter = 0 is missing
    frame_counter = 9 is missing
    frame_counter = 12 is missing

    I determine it by postprocessing the vector of structs. Is not what I want, I would determine it at the "file line processing" time but I can not find a good logic that solves my problem.

    Below is how I do it now:
    Qt Code:
    1. std::vector<MeasurementData> frames;
    2. std::vector<int> counters;
    3.  
    4. for (const auto& frame : frames) // frames is my structs vector
    5. {
    6. int counter = (int)(frame.frame_counter.to_ulong());
    7. counters.push_back(counter);
    8. }
    9.  
    10. // And search for missing frames (assuming vector is ordered)
    11. for (int i = 0; i < counters.size(); i++)
    12. {
    13. if (!std::binary_search(counters.begin(), counters.end(), i))
    14. {
    15. std::cout << "Frame " << i << " is missing" << std::endl;
    16. }
    17. }
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    Franco Amato

  2. #2
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    Default Re: Logic problem

    In my file I have 48 rows
    Is this the same kind of ASCII file you were reading in the last post you made about this kind of thing?

    If it is, why are you using these bitset structures to hold the values after you have parsed the lines? I think you are seriously confused about the range of values that the numbers in your file can have and how to represent them in your code.

    If you are reading an ASCII number from the file where that number can have a range of 0 - 4096, there is no need to represent it in your code as bitset<12>. A normal C++ unsigned 16-bit integer is adequate. A value with a 24-bit range (0 - 16777215) can be held in a 32-bit unsigned integer.

    You have your choice of everything from unsigned char to unsigned long long, and you can do any sort of standard arithmetic processing with them, something you can't do with bitset.

    My need is to find the missing frame_counter values when processing the corresponding file line
    So for your original question:

    1) Create an "expectedFrameCounter" variable outside the loop and initialize it to zero.
    2) Have your processLine() method return the frame_counter value it reads from the line
    3) Compare it to "expectedFrameCounter".
    4) If they match, no problem
    5) If they don't match, then add "expectedFrameCounter" to a list of "missing frames"
    (If more than one frame can be skipped, then add all of the values from "expectedFrameCounter" to the value returned by processLine() - 1).
    6) Set "expectedFrameCounter" to the value returned by processLine + 1 and continue.
    <=== The Great Pumpkin says ===>
    Please use CODE tags when posting source code so it is more readable. Click "Go Advanced" and then the "#" icon to insert the tags. Paste your code between them.

  3. #3
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    Default Re: Logic problem

    The algorithm you proposed does not work (I had thought of something similar at the beginning taking the loop index as expected frame counter)

    Here the explanation:

    Step 0) expected frame_counter: 0, real frame_counter 1 -> missing frame 0? YES, Your algorithm says YES <= OK
    Step 1) expected frame_counter: 1, real frame_counter 2 -> missing frame 1? NO, Your algorithm says YES
    Step 2) expected frame_counter: 2, real frame_counter 3 -> missing frame 2? NO, Your algorithm says YES
    Step 3) expected frame_counter: 3, real frame_counter 4 -> missing frame 3? NO, Your algorithm says YES
    Step 4) expected frame_counter: 4, real frame_counter 5 -> missing frame 4? NO, Your algorithm says YES
    Step 5) expected frame_counter: 5, real frame_counter 6 -> missing frame 5? NO, Your algorithm says YES
    Step 6) expected frame_counter: 6, real frame_counter 7 -> missing frame 6? NO, Your algorithm says YES
    Step 7) expected frame_counter: 7, real frame_counter 8 -> missing frame 7? NO, Your algorithm says YES
    Step 8) expected frame_counter: 8, real frame_counter 10 -> missing frame 8? NO, Your algorithm says YES
    Step 9) expected frame_counter: 9, real frame_counter 11 -> missing frame 9? YES, Your algorithm says YES <= ok
    ...
    etc
    ...

    As you can see, by analizing just 10 lines of the file I should get only 2 missing frames but I get all the lines
    Franco Amato

  4. #4
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    Default Re: Logic problem

    6) Set "expectedFrameCounter" to the value returned by processLine + 1 and continue.
    Are you doing this? After Step 0), if frame 0 is missing, then the expected frame counter for the next frame should be 2, not 1. At Step 0) the actual frame counter is 1, so the next expected frame would be 2 (real frame counter + 1), not 1 as you say in Step 1).

    You have also made an error starting with Step 1) about what value the missing frame should have. In Step 0), frame 0 is the missing one, frame 1 was found instead. In Step 1), you should be looking for frame 2, since that should be the next one after the frame that was found in the previous step. Instead, you ask "missing frame 1?" which is wrong. It should be "missing frame 2?" and the answer is NO.

    If you had implemented the algorithm correctly, the results would be:

    Step 0) expected frame_counter: 0, real frame_counter 1 -> missing frame 0? YES, Your algorithm says YES <= OK
    Step 1) expected frame_counter: 2, real frame_counter 2 -> missing frame 2? NO, Your algorithm says NO
    Step 2) expected frame_counter: 3, real frame_counter 3 -> missing frame 3? NO, Your algorithm says NO
    Step 3) expected frame_counter: 4, real frame_counter 4 -> missing frame 4? NO, Your algorithm says NO
    Step 4) expected frame_counter: 5, real frame_counter 5 -> missing frame 5? NO, Your algorithm says NO
    Step 5) expected frame_counter: 6, real frame_counter 6 -> missing frame 6? NO, Your algorithm says NO
    Step 6) expected frame_counter: 7, real frame_counter 7 -> missing frame 7? NO, Your algorithm says NO
    Step 7) expected frame_counter: 8, real frame_counter 8 -> missing frame 8? NO, Your algorithm says NO
    Step 8) expected frame_counter: 9, real frame_counter 10 -> missing frame 9? YES, Your algorithm says YES <= ok
    Step 9) expected frame_counter: 11, real frame_counter 11 -> missing frame 11? NO, Your algorithm says NO
    <=== The Great Pumpkin says ===>
    Please use CODE tags when posting source code so it is more readable. Click "Go Advanced" and then the "#" icon to insert the tags. Paste your code between them.

  5. The following user says thank you to d_stranz for this useful post:

    franco.amato (29th September 2022)

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