Error "Function subindex is not defined for value of struct"

Hi all,

I'm trying to read in multiple .txt files (each file around 400-900MB) which contain sensor channels channels data.I created a readIn function import_file which gives one output which is struct array of size 1X1 struct with 20 fields and value 1Xno.lines double. This array has all the variables from the data file.

function [Signals] = import_file(filename,startRow)
% Function to read in all channel information from each file.
delimiter = {'\t',' '};
formatSpec = '%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f';
fileID = fopen(filename,'r');
dataArray = textscan(fileID,formatSPec,'Delimiter','MultipleDelimsAsOne',true,'EmptyValue',NaN,'HeaderLines',startRow-1,'ReturnOnError',false);

EXPORT = [dataArray{1:end}];
%Defining Individual channels as struct array
Signals.Time = EXPORT(:,2);
.
.
.
.
Signals.n2 = EXPORT(:,21);
fclose(fileID);

clear file ID;

The rest of program is

myfiles = dir('*.txt');
    for singlefile = myfiles' % forloop to read in each file
 Signals(singlefile) = import_file(file.name,startRow);% storing each file information as a structure inside signal.
end

When I try to run this program I get an error

Function 'subsindex'is not defined for values of class 'struct'

Error in RD_Test_Run(line 69)
Signals(singlefile) = import_files(singlefile.name,startRow);

Could someone please enlighten where I'm going wrong. Thank you in advance.

Answer 1

[Matt J]

 for i=1:length(myfiles)

    singlefile = myfiles(i).name % forloop to read in each file

    Signals{i}= import_file(singlefile,startRow);

 end

[Bharath]

Thanks a lot. That works. But it is taking lot of time to readin data. Is there any way by which I can fasten it up? Like say Preallocation? Because I'm confused how to implement it in my case ( Structures)

[Walter Roberson]

Before the loop you can add

Signals = cell(length(myfiles),1);

but this is probably not going to make a tremendous difference. textscan() just takes time.

Beware that your code is not correct. You have

dataArray = textscan(fileID,formatSPec,'Delimiter','MultipleDelimsAsOne',true'EmptyValue',NaN,'HeaderLines',startRow-1,'ReturnOnError',false);

when you should have

dataArray = textscan(fileID, formatSPec, 'Delimiter', delimiter, 'MultipleDelimsAsOne', true, 'EmptyValue', NaN, 'HeaderLines', startRow-1, 'ReturnOnError',false);

Are you sure you want MultipleDelimsAsOne in conjunction with EmptyValue ?? That makes it difficult to figure out which column a particular value was intended for.

[Bharath]

@Walter Roberson. Thanks for your answer. I'm sorry that was a typo. I edited it.