CODEWITHSUNDEEP
arraysmatlaboop
Paul
Paul

Reputation: 1184

how to get array of properties from array of objects in matlab

I am using an array of objects in my program, and each object has several attributes. I want to be able to extract separate arrays from this array of objects, one array for each attribute. here is a snippet of the relevant code:

dailyDataMatrix(m,n)=dailyData('',''); %creates an mxn array of dailyData objects
for i=1:m
  for j=1:n
  dailyDataMatrix(i,j)=dailyData(datainput1, datainput2)%dailyData constructor, sets attributes
  end
end
dailyDataMatrix.attribute

But when I try to access a certain attribute as in the code above, say of type string, I get a strange result. Instead of getting an array of strings, I get something else. When I try to print it, rather than printing an array, it prints a series of individual values

ans = 'string1' ans = 'string2' ...

When I try to call 

size(dailyDataMatrix.attribute)
className = class(dailyDataMatrix.attribute)

I get "error using size: too many input arguments" and "error using class: The CLASS function must be called from a class constructor."

However, when I write this as 

thing=dailyDataMatrix.attribute
className = class(thing)
size(thing)

I get the response classname = 'double' and size = 1x1.

Why is this not returning an array the same size as dailyDataMatrix? And an aside question is why the two different ways of writing the code above give different results? and how can I get the result that I want?

Thanks, Paul

Upvotes: 2

Views: 1666

Answers (1)

Navan
Navan

Reputation: 4477

You can capture all the outputs using a cell array or using square brackets if the types are same. For regular array when all values are of same type use,

thing=[dailyDataMatrix.attribute];

If the types are different you can use

thing = cell(1,N); % N is the number of elements in dailyDataMatrix
[thing{:}] = dailyDataMatrix.attribute;

Upvotes: 3

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