Subtract a different number from every group n of values in a table

I am trying to find the perturbations in my data based on a 30 minute time average for 24 hour data.

My original data has 1728000 rows, divided by 48 is 36000. So each of the 36000 entries need to subtract value 1 from the other table, the next 36000 entries will subtract value 2. I have tried for loops and I can't get anything to work past the 36000 entries.

I need something to perform the following:

big_table.uprime(1:36000) = big_table.B_Ux_2(1:36000) - thirtymin.u30(1);

big_table.uprime(36001:72000) = big_table.B_Ux_2(36001:72000) - thirtymin.u30(2);

and so on

Answer 1

[ANKUR KUMAR]

You can use reshape to perform operations:

data=randi(20,1,1728000);
B=reshape(data,36000,[]);
B=B-ones(size(B,1),size(B,2)).*[1:size(B,2)];
data_new=reshape(B,size(data,1),[]);

[Stormi Noll]

Reshape can't be used on a table unless it's for a single column. I'm using a table because I have time/date data. The following loop worked, but it takes a long time. I have to do this for 5 minute data (interval = 6000) and it takes too long.

for i = (1:36000:1692001)

for j = (36000:36000:1728000)

for k = (1:48)

big_table.uprime(i:j) = big_table.B_Ux_2(i:j) - thirtymin.u30(k);

end

end

end

ps. I'm new to Matlab

[ANKUR KUMAR]

Could you please attach the variable (in a mat file). It will help us to help you.

[Stormi Noll]

B = reshape(big_table.B_Ux_2 ,6000, []);

for i = 1:288

B(:,i) = B(:,i) - fivemin.u5(i);

end

big_table.uprime5 = reshape(B, size(big_table, 1), []);

I used a combination of our methods. Thanks for the advice.

[ANKUR KUMAR]

Could you please accept the answer if it helps you.