Creating a function for median

Question

Francis Chabot 2021-2-9

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https://ww2.mathworks.cn/matlabcentral/answers/740487-creating-a-function-for-median

评论： dpb 2021-2-10

Hello,

I have a code that helps me calculate the median by SIC code that I'd like to modify to be able to use it as a function.

SICcode = xlsread('G-Score','Active','C3:C11');
ROA = xlsread('G-Score','Active','D3:D11');
SIC = [SICcode(:), ROA(:)];
splitapply(@median,SIC(:,2:end),findgroups(SIC(:,1)/100));
median(SIC(1,2:end));
tSIC=table(SIC(:,1),SIC(:,2:end),'VariableNames',{'SIC','Data'}) 
tSIC.Industry = fix(tSIC.SIC/100); 
tSIC = tSIC(:,[1 end 2]);
rowfun(@(v)median(v,'all'),tSIC,'GroupingVariables','Industry', ...
                    'InputVariables','Data', ...
                    'OutputVariableNames','Median')

So, with this code I am able to compute the median of an industry by the first 2 digit of the SIC code.

The things is I'd like to make a function that will helps me with two things:

Compute the ROA for more than one year, in this case 23 in total.
Create a function that will let me do the same thing for differents statistics (ROE, Total Assets, CFO...), in this case about 20 in total.

I know it doesn't need "a lot" of work to create a function with this code but at this point I can't make it works.

Any helps would be appreciated.

Best regards,

Frank

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Francis Chabot 2021-2-10

在 MATLAB Online 中打开

I did it differently this time.

Data = xlsread('G-Score','All Data');
ROA = Data(2788:5571,2:end);
SICcode = xlsread('G-Score','All','C2:C2785');
SICROA = [SICcode(:), ROA(:,1:end)];
splitapply(@nanmedian,SICROA(2:end,:),findgroups(SICROA(:,1)/100));

It's only when I come to use the splitapply that I can't due to these errors:

Error using vertcat
Dimensions of arrays being concatenated are not consistent.
Error in splitapply>localapply (line 253)
            finalOut{curVar} = vertcat(funOut{:,curVar});
Error in splitapply (line 132)
varargout = localapply(fun,splitData,gdim,nargout);

I know that it is possible because I can compute the median of each lines by doing it that way:

nanmedian(SICROA(2:end,2));

I find weird that it works by doing it separatly but when using it with the splitapply it won't work.

Best regards,

Frank

dpb 2021-2-10

It's the issue I told you about before that there will be different numbers of elements in the groupings if there aren't the same number of elements per group -- and so, since median works by colum, it may also have a different number of results by group.

That's why I told you you needed to use the anonyomous function in order to pass the 'all' parameter so it returns only the overall median of the group each call.

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