Inputting values into a vector using an if statement

Hey there, I am having some troubles with getting a vector out of my code, currently I am only getting a single r value from my code:

Data1.mat is a 1x1 structure with 5 vectors included: A HomeUse, A RawData, a Time stamp, an atmp vector and a srad vector.

%%

clc

clear all

%%

data=load('Data1.mat');

A=40; %m^2

PR=.86; % no unit

r_baseline=.15; % percent

Batter_Capacity=14; % kWh

Price_Elec=0.16; % $0.16/kWh

Tot_Sys_Cost=20000; % $$$$$$$$$$

Time=data.Time;

HomeUse=data.HomeUse;

atmp=data.atmp;

srad=data.srad;

r=reshape(1:length(atmp),[26304,1]);

%%

for i=1:length(atmp)

if atmp(i)>25

r=.15-(atmp(i)-25).*0.0038;

else

r=r;

end

end

Answer 1

[Atsushi Ueno]

I think this is what you would like to do.

% for i=1:length(atmp)
%     if atmp(i)>25
%         r=.15-(atmp(i)-25).*0.0038;
%     else
%         r=r;
%     end
% end
r=.15-(atmp(atmp>25)-25).*0.0038;

[Tru Jacobson]

I am recieving a 1958x1 array instead of the same size of the original vectors. I am guessing that the if statement is a bit funky. Any ideas?

[Atsushi Ueno]

Do you mean "when atmp = [24, 26, 10, 30, 5], r shall be [1; 0.1462; 3; 0.1310; 5]" ?

atmp = rand(1958,1) * 50; % temporary data for example
% r = reshape(1:length(atmp),[1958,1]); % use transpose instead of reshape
r = (1:length(atmp))'; % see https://jp.mathworks.com/help/matlab/ref/transpose.html
%%
for i=1:length(atmp)
    if atmp(i)>25
        r(i) = .15-(atmp(i)-25).*0.0038; % you mean when atmp>25 r is calculated
    else
        r(i) = i; % r=r; you mean when atmp<=25 r is just an index number
    end
end

The code above can be reduced like the code below.

atmp = rand(1958,1) * 50; % temporary data for example
r = (1:length(atmp))';
r(atmp>25)=.15-(atmp(atmp>25)-25).*0.0038;