Any way to subset data from a single Channel (Eg. using thingspeakread) in a MATLAB Visualisation?

Any pointers would be appreciated - I've been looking for a way to do this for hours now.

I have a single channel receiving data from multiple IOT devices including the device name (this is working just fine).

I'd like to plot a value (eg Temperature) over time by device on a single chart.

The bit I can't seem to do is find a way to retrieve data "Where DeviceID = xyz"

Any ideas please??

Answer 1

[Cris LaPierre]

If you have all the data in a single matrix, then the plot function will treat each column as a separate series. Does this get you what you want?

[N S]

Thx for the response - I did look at the matrix but I'm not sure how to create a matrix like that. I can only extract data from the channel using thingspeakread and that seems to be all or nothing - is there something I can do once I've gott the info to subset and construct a matrix??

[Cris LaPierre]

What is the command you are using to read the data? What is the datatype and size of your output?

[N S]

Hi - I haven't started to create anything yet as I couldn't find a way to do the subset of data as I need to.

The data is pretty simple, just a numeric value by date/time. Approx 1 data point per device per minute, somewhere around 10 devices eventually. Does that help?

[Cris LaPierre]

thinkSpeakRead returns the data as an array, table or timetable. From there, you can use normal indexing to select what to plot.

For an array, see here.

For tables and timetables, see here.