MATLAB: JSON decode – lost information

jsonjsondecodeMATLABwebread

Let's say I get this string from the serverside;

{"1D2381B":["fd56c0fd-8882-4b8e-9941-0bd04489981e"],"BZ5ZZ65":["2c768773-7d5f-4d06-8fa1-6ce819dc383a"],"11852420":["b8953809-a264-41b3-a1c3-f3592cd51419"]}

I want to be able to parse and use this information. Matlab automagically decodes it… but it 'makes valid names' of my IDs.

As modifying an ID somewhat destroys it's utility. I'd like a way to prevent or otherwise recover the information. The function 'makeValidNames' returns a second argument, which says which entries were modified.

This information is lost in the JSON decode function. Can anyone help with a workaround, on how I can convert this without the destruction of information?

Best Answer

It's something I've complained about to Mathworks in the early days of jsondecode. In fact, you can use matlab jsonencode to encode a matlab.containers.Map that you would not be able to read back correctly with jsondecode due to that mangling of json keys.

I suggested that jsondecode returns a matlab.containers.Map instead which wouldn't require name mangling and the developer did say that it was something they were considering for a future release. Either they have decided against it or it's yet to be implemented.

I suggest that you raise a service request to Mathworks. The more people complain, the more likely it will change.

In the meantime, I'm afraid you'll have to delegate to a 3rd party parser or write your own. It's not that difficult to parse json actually.

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MATLAB: “str2mat is not recommended”, but what is recommended

You can just replace str2mat by char and it should work:

for ...
   ticklabels = char(ticklabels, char(paramDisplay(paramNum)));
end

If paramDisplay is already a string, you don't need to wrap it into char. You probably don't need the loop either, however I'm puzzled by your loop. The for line implies that that paramDisplay is a 2D array (since you're using size to get the number of columns), but in the body of the loop you're using linear indexing. With linear indexing, you're iterating over the rows first. So it doesn't make sense.

I'm also confused about what paramDisplay is. You use matrix indexing, yet it can be a matrix as that can't be an "array of parameter names". Is it a class?

If paramDisplay were a 1D cell array of strings of varying lengths:

ticklabels = char(paramDisplay{:}) %no need for loop

MATLAB: How to train (manually labeled) x-ray image data using CNN (labeled data in .json format)

Hi Fahad Parvez Mahdi,

Sorry for my late reply, It is because there are so many web link in your json file. Therefore, you have to decode them one by one.

Please refer to the code below, it will help you decode your json file. There are 50 web links.

fname = 'Dental X-Ray Image Dataset 1.json'; 
fid = fopen(fname); 
raw = fread(fid,inf); 
str = char(raw'); 
fclose(fid); 
k = strfind(str,'con');
k=k-3
k(1:2:end)=k(1:2:end)+1
w=1;
for i=1:2:length(k)
val(w) = jsondecode(str(k(i):k(i+1)));
w=w+1;
end

if you have any inquiries, you are always welcome.

Best Answer

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MATLAB: “str2mat is not recommended”, but what is recommended

MATLAB: How to train (manually labeled) x-ray image data using CNN (labeled data in .json format)

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