Creating a data structure by a loop.

Hi everyone, I found some code to make a data structure in matlab, my code is below: So far I have imported a bunch of data from excel as 177x10 matrices (ignore the wavelengths one). So I am trying to create data structures where I can start each structure with the names us_mari., us_urban., us_rural. and us_tropo. and have ten different column matrices within each data structure using field names found in the list_nam. My code below will give one of the structures I want:

wavelengths=xlsread('USstandard_collection.xlsx','sheet1','B14:B190');
usmari_data=xlsread('USstandard_collection.xlsx','sheet1','C14:L190');
usrural_data=xlsread('USstandard_collection.xlsx','sheet1','Q14:Z190');
usurban_data=xlsread('USstandard_collection.xlsx','sheet1','AU14:BD190');
ustropo_data=xlsread('USstandard_collection.xlsx','sheet1','AF14:AO190');

list_nam = {'hwy101_left','beach','field_of_rocks','sears','la_cumbre_golf_course',...
    'dirt_patch_right','hwy101_rightside','parking_lot_flower','middle_school_parking_lot',...
    'stadium'}

for iter=1:length(list_nam)
    us_mari.(list_nam{iter})=usmari_data(:,iter);
end

result:

>> us_mari

us_mari = 

                    hwy101_left: [177x1 double]
                          beach: [177x1 double]
                 field_of_rocks: [177x1 double]
                          sears: [177x1 double]
          la_cumbre_golf_course: [177x1 double]
               dirt_patch_right: [177x1 double]
               hwy101_rightside: [177x1 double]
             parking_lot_flower: [177x1 double]
      middle_school_parking_lot: [177x1 double]
                        stadium: [177x1 double]

My current code only works for the mari data and I also want to do it over the other three: urban, rural, and tropo, so my code I'm working on so far to create 4 datasets in a loop is below:

name_of_data_structure = {'us_mari', 'us_rural', 'us_urban', 'us_tropo'}
data_matrix = {usmari_data, usrural_data, usurban_data, ustropo_data}

for  itt = 1:length(name_of_data_structure)
    for iter=1:length(list_nam)
        name_of_data_structure(itt).(list_nam{iter})=data_matrix(itt)(:,iter);
    end
end

but I get the following error:

Error: File: spectral_data.m Line: 21 Column: 54
()-indexing must appear last in an index expression.

Thanks for all the help and if you see anything else wrong, please let me know! Ben

Answer 1

[Azzi Abdelmalek]

Use {}

name_of_data_structure(itt).(list_nam(iter))=data_matrix{itt}(:,iter}

[Ben]

Thank you that solved that issue, I just have one more question, now I get this error,

Field assignment to a non-structure array object.

    Error in spectral_data (line 21)
            name_of_data_structure(itt).(list_nam{iter})=data_matrix{itt}(:,iter);

Thank you, for what you have done so far, it has helped a lot!

[Ben]

I actually got it to work for the most part using this.

name_of_data_structure = {'us_mari', 'us_rural', 'us_urban', 'us_tropo'}
data_matrix = {usmari_data, usrural_data, usurban_data, ustropo_data}

for  itt = 1:length(name_of_data_structure)
    name_of_data_structure{itt} = struct()
    for iter=1:length(list_nam)
        name_of_data_structure{itt}.(list_nam{iter})=data_matrix{itt}(:,iter);
    end
end

but for some reason, in order to get anything I need to write name_of_data_structure{1}.beach, when I wanted for example was us_rural.beach

Thanks, Ben