MATLAB: Comparison of the fields of two structures with a condition

struct

I need to compare values of two fields of two different structures but with a condition on two other fields of these structures.

suppose that these are the two structures that I want to compare:

a=struct('field1',{},'field2',{},'field3',{})
b=struct('field1',{},'field3',{},'field4',{})

(Of course they're both filled)

I want to comapre values of a.field1 and b.field1 if they are equal then I'll calculate a.field2 – b.field2, after that I have to find max(a.field2 – b.field2)

how can I do it ?

Best Answer

If all the fields are scalar, you don't need any special function. I'm assuming that there can be at most one i and j for which a(i).field1 == b(j).field1. If not, you need to explain which (i, j, or both) can be duplicate and what needs to be done in that case

[~, ia, ib] = intersect([a.field1], [b.field2]); %find location of matching field1 elements of both structure array
maxValue = max([a(ia).field2] - [b(ib).field2])

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MATLAB: Comparing two structures and find the common

common_fields = intersect( fieldnames(structure1), fieldnames(structure2));
for fn = common_fields
    this = fn{1};
    new_struct(1).(this) = structure1.(this);
    new_struct(2).(this) = structure2.(this);
end

MATLAB: How to get jsondecode to preserve map keys (numerical keys are prefixed with ‘x’)

Hello,

From my understanding, you are using jsondecode() to decode an object and then used a jsonencode() to encode it back.

You are trying to decode a JSON object, which gets decoded in MATLAB as a MATLAB struct. A valid field name for struct can start only with letters and can contain letters, digits and underscores.

In this case, the field names ("1", "a.b") being provided are not valid field names for struct so makeValidName function modifies these field names and returns a valid field name when the object is used along with jsondecode(). This has been stated as a limitation for jsondecode() documentation. The makeValidName function constructs valid MATLAB identifiers from input strings, where the field names "1", "a.b" are modified to "x1", "a_b".

The expectation of jsondecode() function is a valid JSON object with valid field names (for struct) should be passed as input.

As a workaround, you may use the containers.Map which returns the map object from the inputs 'keySet' and 'valueSet'. In your case, the 'keySet ' could be the actual field name that you want to store and the struct value can be passed onto the 'valueSet' argument.

The following answer from the community might be of relevance to you:

https://www.mathworks.com/matlabcentral/answers/435390-json-decode-lost-information

Best Answer

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MATLAB: Comparing two structures and find the common

MATLAB: How to get jsondecode to preserve map keys (numerical keys are prefixed with ‘x’)

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