Matlab struct function (structure array)

grammar

s = struct
s = struct(field,value)
s = struct(field1,value1,...,fieldN,valueN)
s = struct([])
s = struct(obj)

explain

s = struct    % Create a scalar without any fields  (1×1)  Structure .

s = struct(field,value) 
% Create an array of structures with specified fields and values .
%value  The input parameter can be any data type , For example, numerical value 、 Boolean value 、 Character or cell array 

% If value Not a cellular array , perhaps value Is a scalar cell array , be s Is a scalar structure 
% for example ,s = struct('a',[1 2 3])  Create a 1×1 Structure , among s.a = [1 2 3]

% If value Is a non scalar cell array , be s Is the dimension and value The same structure array .s Each element of contains  value  The corresponding element of 
% for example ,s = struct('x',{'a','b'},'y','c')  return  s(1).x = 'a'、s(2).x = 'b'、s(1).y = 'c'  and  s(2).y = 'c'

% If value Is an empty cell array  {}, be  s  It's empty  (0×0)  Structure 

s = struct(field1,value1,...,fieldN,valueN)  Create multiple fields 
% aggregate value1,...,valueN Any non scalar cell array in must have the same dimension 

% If value All inputs of are not cell arrays , perhaps value All inputs as cell arrays in are scalars , be s Is a scalar structure 

% If all value All inputs are non scalar cell arrays , be s Has the same dimension as a non scalar cell array 
% For any array whose type is scalar cell array or any other data type  value,struct take value  Insert the content of s In the relevant fields of all elements of 

% If anything value The input is an empty cell array {}, The output s It's empty  (0×0)  Structure 
% To specify an empty field and keep the values of other fields , Please switch to [] As value Input 

s = struct([])  Create an empty without any fields  (0×0)  Structure 

s = struct(obj)  Create include and  obj  The scalar structure of the field name and value corresponding to the attribute of 
%struct  Functions do not convert  obj, It's going to be  s  Create a new structure . This structure does not retain class information , So dedicated 、 Protected and hidden properties in  s  Become a public field 
%struct  Function will warn you when you use this syntax 

Input parameters

filed ： Field name
Field name , Specify as character vector or string scalar . Valid field names begin with a letter , It can contain letters 、 Numbers and underscores . The maximum length of a field name is namelengthmax Value returned by function

value： value
value , Specify as an array of any type . If value Any input is a non scalar cell array , Then all non scalar cell array inputs must have the same dimension . If value Any input is an empty cell array {}, The output is an empty structure array . To specify a single empty field , Please use [].

obj： object
object , Specify as a scalar or an array of objects .struct Function will obj The attribute of is copied into the field of the new scalar structure .struct Functions cannot create structures based on most basic data types . for example , If obj have double or char data type , be struct An error message will be sent . however ,struct The attributes of the table or schedule will be returned as a structure .

Example

example 1: Store relevant data variables in the structure

% Create a structure by adding fields using dot notation 
data.x = linspace(0,2*pi);
data.y = sin(data.x);
data.title = 'y = sin(x)'

The results are shown below ：

% Draw sine wave , Here, reference by field name  x  and  y  Array of values , Then add the title 
plot(data.x,data.y)
title(data.title)

The results are shown below ：

example 2: A structure with one field

% Create a non scalar structure containing a field 
field = 'f';
value = {'some text';
         [10, 20, 30];
         magic(5)};
s = struct(field,value)

% View the content of each element 
s.f

The results are shown below ：

% Accessing fields of non scalar structures （ for example  s.f） when ,MATLAB Return a comma separated list 
% In this example ,s.f  Equivalent to  s(1).f, s(2).f, s(3).f

example 3: A structure with multiple fields

field1 = 'f1';  value1 = zeros(1,10);
field2 = 'f2';  value2 = {'a', 'b'};
field3 = 'f3';  value3 = {pi, pi.^2};
field4 = 'f4';  value4 = {'fourth'};

s = struct(field1,value1,field2,value2,field3,value3,field4,value4)

%value2  and  value3  The cell array of is  1×2  Array , therefore  s  It's also  1×2  Array 
% because  value1  It's a numerical array, not a cellular array , therefore  s(1).f1  and  s(2).f1  Have the same content 
% Similarly , because  value4  The cell array of has a single element , therefore  s(1).f4  and  s(2).f4  Have the same content 

The results are shown below ：

example 4: Structure with empty fields

% Create a structure containing an empty field . Use  []  Specify the value of the empty field 
s = struct('f1','a','f2',[])

The results are shown below ：

example 5: Fields containing cell arrays

field = 'mycell';
value = {
   {'a','b','c'}};
s = struct(field,value)

The results are shown below ：

example 6: Empty structure

% Create an empty structure with multiple fields 
s = struct('a',{},'b',{},'c',{})

The results are shown below ：

example 7: Nested structure

% Create a nested structure , among a Is a structure with a field , This field contains another structure 
a.b = struct('c',{},'d',{})
% see  a.b  The name of the field 
fieldnames(a.b)

The results are shown below ：