Index exceeds matrix dimensions

please how do I solve the problem of "Index exceeds matrix dimensions".

it keeps return an error on this line "datStruct = importdata(fileNameArray(i).name);" showing that fileNamearray has a strcuture of 0x1 and the index i has a 1x1 structure

below is my code

% shear strain 10A_4_4_55+2_4 right cell

clc;clear;

fileNameArray = dir('*.dat');


for i = 1:50
    datStruct = importdata(fileNameArray(i).name);
    a1 (:,i)= datStruct.data(1173,:); 
    a2 (:,i)= datStruct.data(1175,:); 
    a3 (:,i)= datStruct.data(1167,:); 
    a4 (:,i)= datStruct.data(1181,:);
    a5 (:,i)= datStruct.data(1197,:);
    a6 (:,i)= datStruct.data(1213,:); 
    a7 (:,i)= datStruct.data(1250,:); 
    a8 (:,i)= datStruct.data(1309,:); 
    a9 (:,i)= datStruct.data(1369,:); 
    a10 (:,i)= datStruct.data(1425,:);
    a11 (:,i)= datStruct.data(1448,:);
    a12 (:,i)= datStruct.data(1469,:); 
    a13 (:,i)= datStruct.data(1478,:);
    a14 (:,i)= datStruct.data(1476,:);
    a15 (:,i)= datStruct.data(1474,:); 
    a16 (:,i)= datStruct.data(1445,:); 
    a17 (:,i)= datStruct.data(1410,:);
    a18 (:,i)= datStruct.data(1372,:);
    a19 (:,i)= datStruct.data(1311,:); 
    a20 (:,i)= datStruct.data(1233,:); 
    
end;

 


 
%{ 
    
 nucleus

    a1 (:,i)= datStruct.data(1275,:); 
    a2 (:,i)= datStruct.data(1277,:); 
    a3 (:,i)= datStruct.data(1281,:); 
    a4 (:,i)= datStruct.data(1285,:);
    a5 (:,i)= datStruct.data(1315,:);
    a6 (:,i)= datStruct.data(1317,:); 
    a7 (:,i)= datStruct.data(1321,:); 
    a8 (:,i)= datStruct.data(1325,:); 
    a9 (:,i)= datStruct.data(1359,:); 
    a10 (:,i)= datStruct.data(1363,:);
    a11 (:,i)= datStruct.data(1367,:);
    a12 (:,i)= datStruct.data(1398,:); 
    a13 (:,i)= datStruct.data(1402,:);
    a14 (:,i)= datStruct.data(1433,:);
    a15 (:,i)= datStruct.data(1435,:); 
    a16 (:,i)= datStruct.data(1439,:); 

%}

[Stephen Cobeldick]

Numbering variables like that is a sign that you are doing something wrong.

Using indexing makes code simpler and more reliable.

Answer 1

[David K.]

It appears that for some reason fileNameArray is not being populated with values in the line

fileNameArray = dir('*.dat');

Make sure that you that the .dat files you are looking for are in your working folder. If they are in a folder within the working folder you may need to try

dir('*/*.dat')

or

dir('**/*.dat')

[Killian Onwudiwe]

Thank you David K. My working folder has the files I am looking for (though they are in xlsx form) I have also tried to convert it to csv files but yet it gives me the same challenge

[David K.]

The problem is that the string

'*.dat'

literally means to search for all files that are of the type .dat so if the files you want are not .dat files then it will not work. Since you say the files you need are .xlsx, you want your command to be

fileNameArray = dir('*.xlsx');

I would suggest typing that into the command line first so you can be sure all the files are being read in as expected before running it in the script.

[Killian Onwudiwe]

thank you this worked fine for me but gives me another error

Attempt to reference field of non-structure array.

Error in normalcell (line 11)

a1 (:,i)= datStruct.data(1173,:);

P.S. I am a newbie in programming and really dont have deep understanding.

Thank you for helping

[Walter Roberson]

importdata() sometimes returns pure numeric arrays instead of a structure. I avoid using importdata(). You should consider using xlsread() or readtable(); if you have R2019a or later you might be able to use readmatrix()