How to remove empty strings from a MATLAB array of structs

Question

I have a MATLAB array of structs with a field called image_name. There are a few entries where

x(n).image_name = []

(i.e., the nth row of the struct array has an image_name that's empty)

I would like to remove them by trying something along the lines of

idx = [x.image_name] == []
x(idx) = [];

but can't get the indices of the empty strings. Every variation I try generates an error.

How can I find the row indices of the empty strings, so I can remove them?

Answer 1

You can use {} to convert the names to a cell array and then use isempty (within cellfun) to find the empty entries and remove them.

ismt = cellfun(@isempty,  {x.image_name});
x = x(~ismt);

Or in one line

x = x(~cellfun(@isempty, {x.image_name}));

Update

As mentioned by @Rody in the comments, using 'isempty' rather than constructing an anonymous function is significantly faster.

x = x(~cellfun('isempty', {x.image_name}));