Question

I have an array of structs and would like to set all empty attributes to NaN:

structArray = 
29x1 struct array with fields:
    value
    id

How do I set all struct.value attributes to NaN, if they are empty?

If they are empty the conversion [structArray.value] omits the empty elements…

Answer 1

Given this:

x(29).id = [];
x(29).value = [];

You can set the value of all .id fields like this

[x.value] = deal(nan);

To set only a particular subset of values define a mask of values to set and then use it in your assignment statement:

maskEmptyId = arrayfun(  @(a)isempty(a.id),  x  );
[x(maskEmptyId).id] = deal(nan);