Deleting the i-th entry from all fields of a struct

I'm using a struct to hold data on a large sample of patients. Each field corresponds to an attribute or property of the patients. There are some patients whom I wish to remove from the dataset (from the struct). How can I do this?

For example, suppose I wish to remove the i-th patient from the struct. This means I need to delete the i-th values from each field of the struct. I don't know how to do that.

Here is how I'm creating my struct (from a 135737x11 matrix "M"):

patients = struct( 'id', M(:,11), ...
             'PSAtests', M(:,1), ...
             'PSAestimate', M(:,3), ...
             'PSA', M(:,10), ...
             'isActual', 1-M(:,4), ...
             'age', M(:,5), ...
             'cancer', M(:,6), ...
             'cancerAge', M(:,7), ...
             'biopsy', M(:,8), ...
             'biopsyAge', M(:,9) );

Ideally, if I wished to remove all patients over the age of 80, I could do so by something like the following:

patients(patients.age>80) = []

Any ideas? Or if I'm going about this the wrong way, please suggest an alternative data handling strategy. I welcome any comments.

Answer 1

[Daniel Underwood]

For the answer to this question, see the answer to the following question:

http://www.mathworks.com/matlabcentral/answers/4577-convert-matrix-to-vector-of-structs

Answer 2

[David Young]

Have a look at the section in the manual on "Organizing Data in Structure Arrays", also available here.

You can change the organisation of your data to element-by-element, which probably makes sense for a collection of patient records, by creating an array of structures like this:

for k = 1:size(M,1)
    patients(k) = struct( ...
        'id', M(k,11), ...
        'PSAtests', M(k,1), ...
        'PSAestimate', M(k,3), ...
        'PSA', M(k,10), ...
        'isActual', 1-M(k,4), ...
        'age', M(k,5), ...
        'cancer', M(k,6), ...
        'cancerAge', M(k,7), ...
        'biopsy', M(k,8), ...
        'biopsyAge', M(k,9) );
end

Then you can delete a set of records with a small modification of your proposed command:

patients([patients.age] > 80) = [];

(Note the square brackets.)

If you want to retain your existing data structure (perhaps to save memory), then I think that to delete a patient you have to write a loop which deletes the entry from each array in the structure in turn.