how to create for loop in matlab?

Hi All,

I have thousands of images each date has 7 bands. I need to create for-loop to calculate

MNDWI=(b4-b6)/(b4+b6)

here is example of the images

'MOD09A1.A2000057.h21v05.006.2015136062042.hdf_sur_refl_b01_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000057.h21v05.006.2015136062042.hdf_sur_refl_b02_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000057.h21v05.006.2015136062042.hdf_sur_refl_b03_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000057.h21v05.006.2015136062042.hdf_sur_refl_b04_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000057.h21v05.006.2015136062042.hdf_sur_refl_b05_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000057.h21v05.006.2015136062042.hdf_sur_refl_b06_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000057.h21v05.006.2015136062042.hdf_sur_refl_b07_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000065.h21v05.006.2015136062016.hdf_sur_refl_b01_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000065.h21v05.006.2015136062016.hdf_sur_refl_b02_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000065.h21v05.006.2015136062016.hdf_sur_refl_b03_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000065.h21v05.006.2015136062016.hdf_sur_refl_b04_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000065.h21v05.006.2015136062016.hdf_sur_refl_b05_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000065.h21v05.006.2015136062016.hdf_sur_refl_b06_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000065.h21v05.006.2015136062016.hdf_sur_refl_b07_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000073.h21v05.006.2015136060905.hdf_sur_refl_b01_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000073.h21v05.006.2015136060905.hdf_sur_refl_b02_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000073.h21v05.006.2015136060905.hdf_sur_refl_b03_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000073.h21v05.006.2015136060905.hdf_sur_refl_b04_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000073.h21v05.006.2015136060905.hdf_sur_refl_b05_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000073.h21v05.006.2015136060905.hdf_sur_refl_b06_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000073.h21v05.006.2015136060905.hdf_sur_refl_b07_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000081.h21v05.006.2015136075413.hdf_sur_refl_b01_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000081.h21v05.006.2015136075413.hdf_sur_refl_b02_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000081.h21v05.006.2015136075413.hdf_sur_refl_b03_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000081.h21v05.006.2015136075413.hdf_sur_refl_b04_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000081.h21v05.006.2015136075413.hdf_sur_refl_b05_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000081.h21v05.006.2015136075413.hdf_sur_refl_b06_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000081.h21v05.006.2015136075413.hdf_sur_refl_b07_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000089.h21v05.006.2015136062547.hdf_sur_refl_b01_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000089.h21v05.006.2015136062547.hdf_sur_refl_b02_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000089.h21v05.006.2015136062547.hdf_sur_refl_b03_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000089.h21v05.006.2015136062547.hdf_sur_refl_b04_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000089.h21v05.006.2015136062547.hdf_sur_refl_b05_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000089.h21v05.006.2015136062547.hdf_sur_refl_b06_clip.tif_mosaico_ream.tif'
'MOD09A1.A2000089.h21v05.006.2015136062547.hdf_sur_refl_b07_clip.tif_mosaico_ream.tif'

Thank you in Advance

Reyadh

[per isakson]

I cannot even guess how to retrieve b4 and b6 !

[reyadh Albarakat]

Hi per isakson,

each date has 7 bands for example this image MOD09A1.A2000057 which I posted above, has 7 bands. if you read the entire line of each image you will find band number. Here is one of the images, Band no in BOLD (MOD09A1.A2000057.h21v05.006.2015136062042.hdf_sur_refl_ b01_clip.tif_mosaico_ream.tif)

Thank you

Reyadh

[per isakson]

I still don't understand how to find the two numbers to put into this expression

(b4-b6)/(b4+b6)

Answer 1

[hamed amini]

look into sprintf function

>> variable_numbers1 = [1 2 3 ... 1000];
>> variable_numbers2 = [2001 2002 2003 ... 2001000];
>> for i=1:1000
>> eval(sprintf('image_bank.image%d = imread(''fixed_string%d_fixed_string%d.tiff'');',i,variable_numbers1(i),variable_numbers2(i)));
>> end

[Jan]

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

Prefer:

image_bank.image = cell(1, 1000);
for i = 1:1000
  filename = sprintf('fixed_string%d_fixed_string%d.tiff', ...
                      i, variable_numbers1(i));
  image_bank.image{i} = imread(filename);
end

[hamed amini]

Thanks for the link.