Filter löschen
Filter löschen

Detect changes between specific values in a tall array

4 Ansichten (letzte 30 Tage)
Francisco de Juan
Francisco de Juan am 26 Nov. 2021
I need to read through a column in a tall array and detect specific transitions in values.
Let’s say I have a tall vector of integers which indicate the operating modes of a machine. I would like to identify in which lines there are transitions of mode, i.e., 1 ->2, 2 ->4, 4 ->1. The valid transitions are known in advance.
I have tried with movmax, movmin and movmean with some success, but I would like to have a more robust solution. I guess this could be done with matlab.tall.movingWindow and some kind of simple anonymous function, maybe based on diff()?
In practical terms, so that this request can be better understood, I have a tall vector like the first column shown below. I would like to add tall columns to the right marking the initial and final line of each transition.
Tall 1->2 2->4 4->1 1->4
1 0 0 0 0
1 0 0 0 0
1 1 0 0 0
2 1 0 0 0
2 0 0 0 0
2 0 1 0 0
4 0 1 1 0
1 0 0 1 0
Thanks

Antworten (1)

Divyanshu
Divyanshu am 29 Feb. 2024
Hi Francisco,
I have made certain assumptions based on my understanding from the description. Here are the assumptions:
  • You have certain arrays, where 'Tall' array represents various modes of machine while '1->2','2->4' these are logical arrays which indicate whether the machine has made a transition into corresponding mode.
  • The desired output is kind of a vector/array which indicates the rows in which the transition has followed a certain pattern or sequence which is referred as 'Valid Transition'
You can refer the following sample MATLAB script which gives a 'Valid' column vector with values '1' corresponding to rows which have followed the pattern:
Tall = [1;1;1;2;2;2;4;1];
One_Two = [0;0;1;1;0;0;0;0];
Two_Four = [0;0;0;0;0;1;1;0];
Four_One = [0;0;0;0;0;0;1;1];
One_Four = [1;0;0;0;0;0;1;0];
Valid = [0;0;0;0;0;0;0;0];
t = [Tall,One_Two,Two_Four,Four_One,One_Four];
for i=1:height(Tall)
% lets assume 1->2,2->4,4->1 is valid transition.
cond1 = islogical(One_Two(i));
cond2 = islogical(Two_Four(i));
cond3 = islogical(Four_One(i));
if(cond1 && cond2 && cond3)
Valid(i) = 1;
else
Valid(i) = 0;
end
end
t = [t Valid];
Moreover, I have just checked that certain transitions like '1->2, 2->4 ' are done and have not considered the order, for which you can add more conditions as per the use-case and requirement.
  1 Kommentar
Francisco de Juan
Francisco de Juan am 4 Mär. 2024
Thank you for taking the time to respond to my question, even after so much time has passed.
However, I'm not entirely sure if I have been understood correctly. I was referring to MATLAB tall arrays, which are arrays with more rows than can fit in memory. Results are evaluated only when you request them explicitly using gather. Therefore, I don't believe that "height(Tall)" can be used, for example.

Melden Sie sich an, um zu kommentieren.

Tags

Produkte


Version

R2020b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by