We released a new version of MATLAB^® and it’s available now for every ThingSpeak user. MATLAB R2016b includes many new features that make it easy to work with time-stamped tabular data, manipulate, compare, and store text data efficiently, and find, fill, and remove missing data.

With multiple sensors around my house or office, I want to be able to send data to multiple ThingSpeak channels. But, when I want to perform data analysis, I have a hard time working with data from multiple channels. The channels do not have the same time stamps and are out-of-sync with each other.

With R2016b of MATLAB, I am able to use the new timetable data container. Once the data is a stored as a timetable, I can perform powerful operations such as retime, synchronize, and rmmissing.

In this example, I have two sensors outside of my office here in Natick, MA. One sensor is a temperature sensor that is sending data to ThingSpeak channel 163540. My other sensor is writing humidity data to channel 163545. Both channels are public. My goal is to plot temperature versus humidity over one time series. To accomplish this, I will use timetable and synchronize inside of a new MATLAB Visualization on ThingSpeak.

% Read from the temperature channel
temperatureTT = thingSpeakRead(163540,'Fields',1,'NumPoints',100,'outputFormat','timetable');

% Read from the humidity channel
humidityTT = thingSpeakRead(163545,'Fields',1,'NumPoints',100,'outputFormat','timetable');

% Synchronize two timestables and fill in missing data using linear interpolation
TT = synchronize(temperatureTT,humidityTT,'union','linear')

% Plot Temperature and Humidity over time
plotyy(TT.Timestamps,TT.Temperature,...
       TT.Timestamps,TT.Humidity);
        
title('Temperature and Humidity Synchronized From Two Channels')
xlabel('Temperature and Humidity in Natick, MA')
legend('Temperature','Humidity')

The first part of the script reads in ThingSpeak data from two different channels and stores the data in two timetables. Once the data is stored in a timetable, I am able to take advantage of synchronize. With synchronize, I can combine both timetables with one time series and fill in missing data using linear interpolation. This results in a plot that shows my data over time without any missing data. To create the plot, I signed into ThingSpeak, selected Apps, and created a new MATLAB Visualization with my MATLAB code.

All ThingSpeak users are able to try this example or explore the other new MATLAB features directly on ThingSpeak. I will leave my temperature (163540) and humidity (163545) channels public, so you can try out timetable example without having to connect devices to ThingSpeak.

Allie Fauer, a designer from New York, has released another awesome Instructable tutorial on how to build a “To Do List Reminder Light”. This project is very creative and easy to build on your own. Allie tracks her tasks on an app called Todoist. With a little help of the MATLAB Analysis app on ThingSpeak, Allie is able to analyze her tasks and alert herself of anything overdue. She gently reminds herself with a glowing “Remembrall” globe.

Allie uses the MATLAB Analysis app on ThingSpeak to check her to do list and see if anything is overdue. If a task is overdue, the MATLAB code writes the task overdue into a ThingSpeak channel. The MATLAB code is very straightforward and does a bit of analysis on her task list to see what is overdue. To get the MATLAB Analysis code to keep checking her task last, she schedules the MATLAB code using the TimeControl app on ThingSpeak.

Allie also has other ideas on how to make use of her status light:

• Alert you when you’ve forgotten to water your plants
• Tell you when you’re out or range of important objects like your keys or wallet
• Combine with IFTTT to alert you when you’ve forgotten to respond to emails or phone notifications

To build your own Remembrall light, follow the step-by-step tutorial on Instructables.

We launched MATLAB Analysis and Visualizations on ThingSpeak last year and have noticed a sharp increase in IoT analytics being used in your projects. We are seeing everything from analyzing squirrel behaviour to analyzing traffic patterns. As we are all learning how to use MATLAB in our IoT projects, we need to take notice of MATLAB Central.

MATLAB Central is “a place where you can get answers.” We have over 100,000 community members and MathWorks employees all sharing projects and files, experience, and answering questions. And, ThingSpeak is showing up on MATLAB Answers and File Exchange. This is great news for the ThingSpeak Community. If you already have a MathWorks user account and use it on ThingSpeak, you already have access to MATLAB Central. All you have to do is sign in. If you are new to MathWorks, you can sign up for a free user account to gain access to MATLAB Central and other features of ThingSpeak.

Check out Ned Gulley’s post, “Going Way Back with MATLAB Central” to learn about how the MATLAB community has formed over the years.

Cheers to MATLAB Central hitting the 15th year mark! We are happy to be a part of the story.