help with inefficient code

Hi, I have those lines in my script that they purpuse is to fix jumps in a clock (it runs on a table). for instance this is the data:

1913834560

1993310708

177158681 + 1993310708

270995495 + 1993310708

2036984230 + 1993310708

2057526148 + 1993310708

2064917157 + 1993310708

2089319288 + 1993310708

6799572 [phone] + 1993310708

13663870 [phone] + 1993310708

in this case the jump is in the bolt line and the correction will be to add the bolt value to all the later values until the next jump (as sown in the bold summing), and so on.

I write this code, but it takes forever to run on ~500K lines, any ideas to improve it?

thanks!

prev = 0;       %time linearity 
sum = 0;
for i = 2:height(T1(:,1))
  if prev > T1.time(i)
    sum = sum + prev;
  end
  prev = T1.time(i);
  T1.time(i) = T1.time(i)+sum;
end

Answer 1

[Les Beckham]

Try this.

There may be a more efficient approach but I'm pretty sure this will be faster than what you have now.

T1.time = [
1913834560  
1993310708 
177158681 
270995495 
2036984230
2057526148
2064917157
2089319288
6799572 
13663870 ];

del = diff(T1.time);
idx = find(del<0);
sum = zeros(size(T1.time));
for i=1:length(idx)
    sum(idx(i)+1:end) = sum(idx(i)+1:end) + T1.time(idx(i)-1);
end

T1.time_adjusted = T1.time + sum; 

% plot to visualize results
plot(1:length(T1.time), T1.time, 1:length(T1.time), T1.time_adjusted)
grid on

[sani]

thanks! it run much faster than before!

[Les Beckham]

You are welcome. Glad that it helped.