calculate how many state changes and time ThingSpeak

good morning!, I'm learning in MatlLab and ThingSpeak, and I'm a bit lost ... I have a variable that changes state from 0 to 1. And I want to know how I can calculate the times it changes state, and the time that remains for Example in state 1. Can you help me? Thank you so much

Answer 1

[Simran]

Hi @cesc bonet,

I see that you want to calculate the number of times your data’s state changes and the duration a variable remains in that specific state. To do so you can follow these steps:

1.) Retrieve your data from “ThingSpeak”.

% Define your channel ID and read API key 
channelID = YOUR_CHANNEL_ID; 
readAPIKey = 'YOUR_READ_API_KEY'; 
% Read data from ThingSpeak 
data = thingSpeakRead(channelID, 'ReadKey', readAPIKey, 'Fields', 1, 'NumPoints', 8000); 

2.) Once you have your data, you can calculate the number of times the variable changes state from 0 to 1 or 1 to 0 as follows.

% Calculate state changes 
stateChanges = diff(data) ~= 0; 
numStateChanges = sum(stateChanges); 

3.) Now for calculating time spent by the variable in say state 1, you can find the indices where the variable is 1 and compute the time difference.

% Assume your data is sampled at regular intervals (e.g., every minute) 
samplingInterval = 1; % in minutes 

% Find indices where the state is 1 
stateOneIndices = find(data == 1); 

% Calculate the total time in state 1 
totalTimeInStateOne = numel(stateOneIndices) * samplingInterval; 

I did this with an example data, and the results were up and running.

You can refer to the following documentation:

“thingspeak”-

https://www.mathworks.com/help/releases/R2021a/thingspeak/index.html

“thingSpeak Read” –

https://www.mathworks.com/help/releases/R2021a/supportpkg/android/ref/thingspeakread.html

“diff” function – https://www.mathworks.com/help/releases/R2021a/matlab/ref/diff.html

“find” function -

https://www.mathworks.com/help/releases/R2021a/matlab/ref/find.html