MATLAB: Need help concatenating data with struct field name

struct

I have a struct (s) with Field (name) i'm looking to create a 'name' array so that i can concatenate it with data. the field 'name' is file names and the data is range values calculated from each file.

How can i place the files names in column (1) and the range values that go with each name in column (2)?

Best Answer

Create a cell array from the structure field:

names = {s.name}

This syntax uses a comma-separated list:

https://www.mathworks.com/help/matlab/matlab_prog/comma-separated-lists.html

https://www.mathworks.com/matlabcentral/answers/320713-how-to-operate-on-comma-separated-lists

Once you read them you will understand that my answer is equivalent to this:

C = {s(1).name, s(2).name, s(3).name,..., s(end).name}

Related Solutions

MATLAB: How to convert struct filed to cell array before R2016a

You could use the comma-separated list expansion

For example, if you had a struct with 3 fields as follows:

>>s(1).category = 'tree1';s(1).height = 37.4; s(1).name = 'birch1';

>>s(2).category = 'tree2';s(2).height = 37.5; s(2).name = 'birch2';

To convert the 'name' fields into a cell array A,

>>A = {S(:).name}

In your case, it would be:

>> myCell = {mystruct(:).name}

MATLAB: How to preallocate memory for a structure in MATLAB 7.6 (R2008a)

There is a way to preallocate memory for a structure in MATLAB 7.6 (R2008a) using the STRUCT and REPMAT commands.

EXAMPLE 1: A structure with two fields

s.field1

s.field2

field_names = {'field1','field2'}; % Cell with field names
empty_cells = repmat(cell(1),1,numel(field_names));
entries = {field_names{:} ; empty_cells{:}};
s = struct(entries{:});

EXAMPLE 2: A structure with a field with a subfield

s.field1.subfield

s = struct('field1',struct('subfield',cell(1)));

EXAMPLE 3: An array of structures

v(1).field1

...

v(100).field1

s = struct('field1',cell(1));
v = repmat(s,100,1);

Even though the data elements pointed to by the different fields in a structure are not stored contiguously, a benefit of preallocating structures is that you avoid the (possibly time-consuming) operation of dynamically growing the structure field header. Please refer to the following documentation page for more information:

http://www.mathworks.com/help/matlab/matlab_prog/memory-requirements-for-a-structure-array.html

Best Answer

Related Solutions

MATLAB: How to convert struct filed to cell array before R2016a

MATLAB: How to preallocate memory for a structure in MATLAB 7.6 (R2008a)

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