using the int i as output name

Hi,everyone.I would like to ask a question about using the int i as output name , I hope someone could help me . such as for i=1:30; I have a function I would like to put 30 different input using for loop . just like input (i)=xxx ->my program->output (i)=xxxx I would like to have 30 input(some audio files 1.wav 2.wav 3.wav ............) and 30 output , output 1 output 2 output 3......, I have tried output(int i) that's not works , also int2str(i) not working too. could anyone tell me how to do that , thanks a lot .

Answer 1

[Walter Roberson]

http://matlab.wikia.com/wiki/FAQ#How_can_I_create_variables_A1.2C_A2.2C....2CA10_in_a_loop.3F

[Sobel Captain]

I'm sorry , I can't get the answer there , anyway I have finished the input part already . now I just need is when i=1 output1=???? i=2 output2=????? .......... and the output are not files are some values . I hope output 1-10 shown at the work space m I have tried to use the method you provide but not work , or maybe I missed .

[Walter Roberson]

The answer is "DO NOT DO IT".

There are a number of different things that you can do. One would be to assign to output{i}

For example,

for K = 1 : 10
  thisfilename = sprintf('Selfie%04d.tif', K);
  thisimage = imread(thisfilename);
  grayimage = rgb2gray(thisimage);
  output{K} = grayimage;
end

This would produce output{1}, output{2}, output{3} and so on, rather than trying to produce output1, output2, output3, and so on.

[Sobel Captain]

So it should be in cell ?

[Image Analyst]

It doesn't need to be a cell array - it depends what your output is. If the output is just a single number, or an array of numbers, you can use a numerical array instead of a cell array. If the output is a string of different lengths each time, then you'll need a cell array.

[Walter Roberson]

Yes, put it in a cell.

[Sobel Captain]

oh....another problems now i have 2 for loop now , outer loop i=1:10 inner loop k=1:3 and if my output want to be a cell ( output to cols and rows depends on i and k , such as i=1 k=1 fill in the 1:1 of the cell i=10 , k=3 , fill in the 10:3 ) so that's should be a 3x10 cell. and I tried to use( ans{i,k}=result; ) , the cell become 10x10 and so many blank values , is there anyway to do that , thanks a lot for your help , I am new to matlab .

Answer 2

[Thorsten]

This is a possible framework of how to process 30 files:

for i = 1:30

    input_filename = sprintf('%d.wav', i)
    % read input_fileame, compute output

    output_filename = sprintf('output%d', i)
    % write output to file

end

[Sobel Captain]

thanks a lot , but my output is not files is some values , I want it to be shown at the workspace(right side of matlab)

output_filename = sprintf('ans%d', i); output_filename=myans;

and I hope there are ans 1 ans 2 ...... ans 30 at the workspace ,myans is the result of the program, but I tried that method , not works

[Thorsten]

You can create dynamically named variables with eval, but this is not considered good programming practice:

 eval(['ans', int2str(i) '= myans;'])

Instead, if myans has a different size for different i, use

ans{i} = myans;

or, if myans has the same size for all i:

ans(i) = myans; % if myans is a single value

or

ans(i,:) = myans; % if myans is a 1xn vector

or

ans(i, :,:) = myans; % if myans is a n x matrix

and so on.

Answer 3

[Stephen23]

http://www.mathworks.com/help/matlab/matlab_prog/string-evaluation.html

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

[Ilham Hardy]

This is everywhere :D

[Stephen23]

Yep, because beginners keep dreaming it up as The Best Way To Program™.