reading Excel data from Matlab, slow process

Hi everyone,

Got a question...

I have my data stored as Excel files, I use 'xlread' command to read them, calculate the average, and then write the results again on the same Excel files. I have about 3000 files and each file has 1000 samples. These are the codes for my programme:

clc

clear d

clear all

format long

a=0;

b=0;

c=0;

h=1;

d = zeros(1000, 1);

for count=1:2632
        if a==45

           a=0;

           b=b+1;

       end

          for cell=11:1010

              format bank

                d(h,1)=xlsread(['D:\S9_G24' '\X' num2str(a) 'Y'

   num2str(b) 'Z' num2str(c) '.xls'],1,['B' num2str(cell)]);

                h=h+1;

                if h==1001

                    aver=mean2(d);

                    xlswrite(['D:\S9_G24' '\X' num2str(a) 'Y' 

num2str(b) 'Z' num2str(c) '.xls'],aver,1,'B1012');

                    a=a+1;

                    h=1;

                end

          end

end

Codes are fine, but the time it takes is extremely long. It is killing me as I am a bit in rush to get these results. Should I convert my data to a special format or something? I was wondering if anyone has got a good suggestion to speed up the process. I appreciate your help.

BW,

S:-)

[Jan]

Please do not post a question twice.

Answer 1

[Jan]

Do not read the input element by element but the complete column at once:

d = xlsread(sprintf('D:\S9_G24\X%dY%dZ%d.xls' a, b, c), ...
            1, sprintf('B%d:B%d', 10, 1010))

Some other notes:

• Do not use "cell" as name of a variable, because this overwrites an important Matlab command.
• The repeated application of "format bank" wastes time.
• Your input d is a vector. Then mean is more apropriate than mean2.

[S]

Thank you very much for your help.

Answer 2

[Steven]

To get around the fact that the xlsread & xlswrite commands are very slow you'll need to use ActiveX commands. They aren't complicated at all and are explained very clearly on the following website: http://www.orient-lodge.com/node/3430

[S]

Thanks Steve!

[Steven]

I'm changing all my m files as well.. one that used to run for 2 weeks now does the same job in 8hrs.