How to restart the time for each trial? (help with a for loop in a table)

I have a table with two columns, TrialNumber and Minutes that I've attached.

I want each trial to start from 0. I was able to restart the the time for the entire table but not sure how to do it for each trial. Here is what I have so far:

u = unique(tt.TrialNumber);
for k = 1:length(u)
  b = find(tt.TrialNumber==u(k));
  Mins = (tt{:,2} - tt{1,2});
end

[Sargondjani]

It is not clear to me what you want: "I want each trial to start from 0"?

[Mirthand]

15	0
15	0.0263665500000001
15	0.0676836666666669
15	0.0677631000000001
15	0.0678337500000001
15	0.0678979666666670
15	0.0679582166666668
15	0.0680155833333336
15	0.0680712166666670
15	0.0681252833333335

Trial 15 would start like this where instead of starting from 2.6621, it starts from 0.

Then the next trial, 30, the minutes would restart from 0 as well.

Answer 1

[Prabhan Purwar]

Hi Mirthand,

Kindly have a look at the following example code using rowfun.

tt.TrialTime=cell2mat(rowfun(@(m)m-m(1),tt,'GroupingVariables','TrialNumber', ...
                                           'InputVariables','Minutes','OutputFormat','cell'));

Output

>>head(tt)

8×3 table

TrialNumber Minutes TrialTime

___________ _______ _________

15 2.594 0

15 2.6203 0.026367

15 2.6616 0.067684

15 2.6617 0.067763

15 2.6618 0.067834

15 2.6619 0.067898

15 2.6619 0.067958

15 2.662 0.068016

>> i30=find(tt.TrialNumber==30);

>> tt(i30:i30+7,:)

8×3 table

TrialNumber Minutes TrialTime

___________ _______ _________

30 5.8881 0

30 5.9285 0.040365

30 5.9602 0.072087

30 5.9603 0.072205

30 5.9604 0.072305

30 5.9605 0.072389

30 5.9606 0.072463

30 5.9607 0.072535

Hope it helps!

Thanks