How to speed up this code?

Question

Serbring 2019-10-9

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https://ww2.mathworks.cn/matlabcentral/answers/484320-how-to-speed-up-this-code

评论： Serbring 2019-10-11

Hi all,

I have several CANBUS .ASC files that I have to convert to .MAT files for further analysis. In particolar, I need a struct which contains some specified signals where the list is contained in a variable called Signals2Load, which in turn they are contained in a list of messages named Message2Load. Due to the fact that the functions canSignalImport and canSignalTimetable do not work (I am in contact the MathWorks support for this), I had to create my own code. Below, you will find the code. Unfortunately, it is pretty slow for a 1h log (more than 3e6 messages to analyse), it takes almost two hours for the conversion. What could I do for speeding up the code?

Thanks.

Best regards,

Michele

    message=canMessageImport([ASCFiles(iASC).folder '\' ASCFiles(iASC).name],'Vector',candb,'OutputFormat','timetable');
    messageStruct=table2struct(message);
    Duration=floor(seconds(message.Time(end)));
    CanData(iASC).Time=[0:DT:Duration];
    Message2Sel=find(contains({messageStruct.Name},Message2Load));
    if length(unique({messageStruct(Message2Sel).Name}))~=length(Message2Load)
        warning(['The following messages were not found ']);
        setdiff(Message2Load,unique({messageStruct(Message2Sel).Name}))
    end
    for i=1:length(Message2Sel)
        Sig=fieldnames(messageStruct(Message2Sel(i)).Signals);
        [Sig2Sel iSig2Load iSig]=intersect(Signals2Load,Sig);
        if isempty(iSig2Load)==0                           
            for iSigFound=1:length(Sig2Sel)
                Sigs{iSig2Load(iSigFound)}=[Sigs{iSig2Load(iSigFound)}; messageStruct(Message2Sel(i)).Signals.(Sig{iSig(iSigFound)})];
                Time{iSig2Load(iSigFound)}=[Time{iSig2Load(iSigFound)}; seconds(message.Time(Message2Sel(i)))];
            end
        end
    end

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Serbring 2019-10-9

编辑：Stephen23 2019-10-10

在 MATLAB Online 中打开

Annotazione-2019-10-09-143423.png

Here we go.

EDIT: external link removed and image uploaded.

I do not understand, in which line the Tabular.dotParenReference is called in my code. Considering the number of iterations, I suppose that this is caused by this line:

             Sigs{iSig2Load(iSigFound)}=[Sigs{iSig2Load(iSigFound)}; single(messageStruct(Message2Sel(i)).Signals.(Sig{iSig(iSigFound)}))];

Serbring 2019-10-11

在 MATLAB Online 中打开

Annotazione 2019-10-11 072207.png

Hi all,

I have updated the function and the code speed has improved, but it is still slow. In the attachment, you will see the results of the code profile. As you can see the slow processing time is caused by "matlab self time (built-in, overhead,...)".

According to the profile results, this line is the critical code line:

Pos2Paste=min(find(isnan(Sigs{iSig2Load(iSigFound)})))

which I have improved a bit by substituing it with this line (i do not have the results of the profile because the code is still running):

Pos2Paste=find(isnan(Sigs{iSig2Load(iSigFound)}),1); %(*)

As I understand, this line is critical because there are many calls and many function calls. I need this function, because, the signals in the messageStruct have a different timestep and therefore, I need a cell array rather then a simple array. So what I do is saving the signal found in each message in the first NaN element of each Sigs cell ellement.

Any suggestion for a further increase of the code is welcome.

Below an updated version of my code (the line is line (*) is not in this code and niether is the result of the profile.

for iASC=1:length(ASCFiles)    
    message=canMessageImport([ASCFiles(iASC).folder '\' ASCFiles(iASC).name],'Vector',candb,'OutputFormat','timetable');
    messageStruct=table2struct(message);
    MessTime=message.Time;
    Duration=floor(seconds(MessTime(end)));
    clear message
    CanData(iASC).Time=(0:DT:Duration);
    Message2Sel=find(contains({messageStruct.Name},Messages2Load));
    UniqueMessFound=unique({messageStruct(Message2Sel).Name});
    UniqueMessageCount=countcats(categorical({messageStruct(Message2Sel).Name},UniqueMessFound));
    for iSig=1:size(Signals2Load,1)
        Time{iSig}=NaN(UniqueMessageCount(strcmp(UniqueMessFound,Signals2Load{iSig,2})),1);
        Sigs{iSig}=NaN(size(Time{iSig}));
    end
        
    
    for i=1:length(Message2Sel)
        Sig=fieldnames(messageStruct(Message2Sel(i)).Signals);
        [Sig2Sel , iSig2Load , iSig]=intersect(Signals2Load,Sig);
        if isempty(iSig2Load)==0                           
            for iSigFound=1:length(Sig2Sel)
                Pos2Paste=min(find(isnan(Sigs{iSig2Load(iSigFound)})));
                try
                    Sigs{iSig2Load(iSigFound)}(Pos2Paste)=single(messageStruct(Message2Sel(i)).Signals.(Sig{iSig(iSigFound)}));
                catch
                    i;
                end
                Time{iSig2Load(iSigFound)}(Pos2Paste)=single(seconds(MessTime(Message2Sel(i))));
            end
        end
    end
end

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How to speed up this code?

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