Subtract data from two columns and show result in 3rd column

 I have the following data in an excel sheet

   A      B     C
 736     373 
 734     371 
 725     364 
 719     361 
 711     353 
 706     347 
 699     342 
 689     337 
 680     327 
 676     318

So basically I want to run this as A(1) - B(1),A(2) - B(2)..A(n) -B(n) and it should create the outputs at C1, C2...Cn respectively. Can anyone help me on this?

[per isakson]

This is an Excel question. See the Excel Help.

[KRUNAL]

I want to write a script that can do this kind of subtraction. Is it possible?

[Jasmine]

Yes, this is possible. But why wouldn't you just use Excel?

Anyway you need to read the data into MATLAB

data = xlsread('filename')
for i=1:size(data,1)
   output(i) = data(i,1)-data(i,2)
end
fulldata = cat(2,data,output)
xlswrite('filename',fulldata)

Or something like that anyway... syntax may be slightly off, as I haven't tested it.

[Benjamin]

thanks for this helpful answer.

But in every loop, if the size of the matrix (output here) changes Matlab gives error of different matrix sizes. Is there anysolution for that.

FYI: my Matlab code generates a matrix of [A] = n*2 and in every loop (for i = 1:10) n changes. I would like to store all A results in another B matrix.

Answer 1

[Joseph Cheng]

Read in the data using xlsread() and write it with xlswrite

 A = xlsread(____);
 A(:,3) = A(:,1)-A(:,2);
 xlswrite(____)

[KRUNAL]

My file name is dstfile and I tried running this code with columns AA and AB as below :

for i=2:11

X = xlsread(dstfile,'AA: AB');
X(:,3) = X(:,1)-X(:,2);
xlswrite (dstfile,'AC');

end

But it shows me error as

Error using xlsread : Data range 'AA: AB' is invalid.

[Joseph Cheng]

there is an extra space between the : and AB. you should have 'AA:AB'

[KRUNAL]

Hey I got this answer.Just made some minor yet important changes and it worked.My next issue in this I want to put a condition in this like if

B- A > some number ,

it should write "check values again"

else it should write "no change" in column AC instead of the difference value

[Joseph Cheng]

For this i would, have

 C = B- A;
 ind = C== some number; %1's where you want to check values again.

 C = cell(size(C)); %make a cell array so you can have different length text.
 C(ind) = {'check values again'}; %for the indexes (marked with logical 1) put in this text.
 C(~ind) = {'no change'}; %for !ind (inverse) put no change.

then write it to column AC.

[KRUNAL]

I didn't quite get you Joseph. 1st of all tell me how should I convert and make

A(:,3) = A(:,1)-A(:,2)

to 

C = B- A;
form?

[KRUNAL]

Did you mean this:

 for i=2:11

X = xlsread(dstfile);
X(:,3) = X(:,2)-X(:,1);
Y = int2str (X(:,3));
ind = Y >= 350; %1's where you want to check values again.
Y = cell(size (Y)); %make a cell array so you can have different length text.
Y(ind)= {'check values again'}; %for the indexes (marked with logical 1) put in this text.
Y(~ind)= {'no change'}; %for !ind (inverse) put no change.
xlswrite (dstfile,Y,sheet,'AC');
end

If I write this way, I get output as "no change" in AC, AD and AE column

[Joseph Cheng]

Why is there a for loop? does dstfile change base on the loop? Also if it outputs is in AC, AD, and AE what is the size of the Y array? is it one column or 3?

Answer 2

[KRUNAL]

I wrote the code as follows :

 for i=2:11

X = xlsread(dstfile);
X(:,3) = X(:,2)-X(:,1);
Y = num2str (X(:,3));
if (Y > 300)
 Y = {'ok'};
 xlswrite (dstfile,Y,sheet,'AC');
else
Y = {'Check'};
 xlswrite (dstfile,Y,sheet,'AC');
end

 end

But it is updating only cell AC1 and it is writing "check" in that cell.Can anyone suggest where I am going wrong?

[Joseph Cheng]

because in your if statement you're not going through each Y index. additionally the step above you're going Y = num2str so you're converting it to a string and ask the "STRING" if it is greater than 300.

[KRUNAL]

ok..got my mistake. Finally the code is running..thank you