How do I find out a struct is empty?

150 visualizaciones (últimos 30 días)
Sean
Sean el 27 de Sept. de 2023
Editada: Sean el 28 de Sept. de 2023
There are instances in a .mat file where there is information and no information within a particular struct. I'm trying to figure out how to identify that within the struct where there is no furture information avaliable, it's an empty struct.
Let's say a .mat file contains below
A = struct;
A.B = '1';
A.C = '2';
A.D = '3';
but there is another file that contains only what's below
A = struct;
Depending on what which file, or mutiple files that contain various numbers of variables, how do I check if a struct is empty so that I'll be able to initialize the data that is not empty into EditFields of an application.

Respuesta aceptada

Voss
Voss el 27 de Sept. de 2023
It looks like you want to find out whether a struct has any fields or not, for which you can use isempty(fieldnames(A))
A = struct;
A.B = '1';
A.C = '2';
A.D = '3';
isempty(fieldnames(A))
ans = logical
0
A = struct;
isempty(fieldnames(A))
ans = logical
1
  2 comentarios
Voss
Voss el 27 de Sept. de 2023
Editada: Voss el 27 de Sept. de 2023
Whether the struct is empty is another question, as empty and non-empty struct arrays can have fields or no fields.
A = struct('B',{}); % empty struct array with one field ('B')
is_empty_struct = isempty(A), has_no_fields = isempty(fieldnames(A))
is_empty_struct = logical
1
has_no_fields = logical
0
A = struct('B',{1 2 3}); % non-empty (size 1-by-3) struct array with one field ('B')
is_empty_struct = isempty(A), has_no_fields = isempty(fieldnames(A))
is_empty_struct = logical
0
has_no_fields = logical
0
A = rmfield(A,'B'); % non-empty struct array with no fields
is_empty_struct = isempty(A), has_no_fields = isempty(fieldnames(A))
is_empty_struct = logical
0
has_no_fields = logical
1
A = A([]); % empty struct array with no fields
is_empty_struct = isempty(A), has_no_fields = isempty(fieldnames(A))
is_empty_struct = logical
1
has_no_fields = logical
1
Sean
Sean el 28 de Sept. de 2023
Editada: Sean el 28 de Sept. de 2023
Thank you for helping me out, I tried to implement it, but I implemented a try catch statement and works.

Iniciar sesión para comentar.

Más respuestas (0)

Categorías

Más información sobre Structures en Help Center y File Exchange.

Productos


Versión

R2018b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by