how to use unique command for the structured array

How do I use unique command for a structured array and do the that only based on data of one part of that array. for example:

"a" is a struct array with fields:

      z
      fit

and

a(1).fit = [5;7]
a(2).fit = [3;8]
a(3).fit = [5;7]

a(1).z = 'Sunday'
a(2).z = 'Monday'
a(3).z = 'Tuesday'

I want to delete the repetitive raw 3, i.e. "a(3).fit = [5;7]" from structure array and its related raw which is "a(3).z = 'Tuesday'" to have :

    a(1).fit = [5;7]
    a(2).fit = [3;8]

    a(1).z = 'Sunday'
    a(2).z = 'Monday'

[Guillaume]

a.fit(1) = [5;7]

is not valid matlab (you're assigning two elements 5 and 7 to a single element fit(1)). The same is true of a.z(1) = somevector.

Did you actually mean

a(1).fit = [5;7]
a(2).fit = [3;8]
a(3).fit = [5;7]

which would make a a 3x1 or 1x3 struct array with scalar fields?

[meh alipoo]

Thank you for your comment you are true I edit my mistake

Answer 1

[Guillaume]

Assuming you actually meant a structure such as the one created by:

a = struct('fit', {[5;7], [3;8], [5;7]}, 'z', {'Sunday', 'Monday', 'Tuesday'})

Then the following will work:

[~, idx] = unique([a.fit].', 'rows', 'stable');  %stable optional if you don't care about the order.
 a = a(idx)

[a.fit] concatenates the columns in each a.fit to make a single matrix (so all the columns must be the same size). It's then transposed so that unique can work on the rows (formerly columns). The 2nd return value of unique gives you the indices of the rows that were kept, which are the indices of the structure elements to keep.