How do I read the last 3 Thinkspeak channel statuses into an array?

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Chris
Chris 2025-5-9
评论： Chris 2025-5-9
I am currently running a ThingSpeak Maltlab analysis that reads the latest channel status and acts on it. I am using this code, which works fine:
url='https://api.thingspeak.com/channels/mychan/feeds/last.json?api_key=mykey&status=true';
lastData=webread(url);
status = [lastData.status];
I am trying to figure out how to change this to read the last 3 channel statuses and put them into an array like status(i) where i goes from 1-3? This url returns the 3 statuses I want:
url = https:'//api.thingspeak.com/channels/mychan/status.json?api_key=mykey&results=3'
But I can't figure out how to get them into an array to work with. Does anyone know how to do this? Thanks.
  2 个评论
Image Analyst
Image Analyst 2025-5-9
编辑：Image Analyst 2025-5-9
Does anything in the url change when you "read the last 3 channel"? Like mychan or something? Or do you call the same URL, just in a loop after a time delay? Like
for timePoint = 1 : 3
lastData=webread(url);
status(timePoint) = lastData.status;
pause(2); % Pause 2 seconds.
end
What is the lastData variable? What does this show
lastData
whos lastData
Chris
Chris 2025-5-9
No, the channel and the key are identical. Here are the results I get if I use those urls in a browser (first for the last status, then for the last 3):
{
"created_at": "2025-05-09T14:07:20Z",
"entry_id": 1998612,
"field1": "-0.04087",
"field2": "506",
"field3": "0",
"field4": "0",
"field5": "1008",
"field6": "0",
"field7": "464",
"field8": "0",
"status": "000000"
}
When querried for last 3 statuses:
{
"channel": {
"name": "Boiler 2",
"latitude": "4x,xx",
"longitude": "-7x.xx",
"elevation": "11"
},
"feeds": [
{
"created_at": "2025-05-09T14:07:35Z",
"entry_id": 1998613,
"status": "000000"
},
{
"created_at": "2025-05-09T14:09:35Z",
"entry_id": 1998614,
"status": "000000"
},
{
"created_at": "2025-05-09T14:11:35Z",
"entry_id": 1998615,
"status": "000000"
}
]
}

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采纳的回答

Christopher Stapels
编辑：Christopher Stapels 2025-5-9
url = 'https://api.thingspeak.com/channels/mychan/status.json?api_key=mykey&results=3';
data = webread(url);
statusArray = {data.feeds.status};
Gives you a cell array of statuses (statusi?) :).
Full Disclosure: I did use a little Gen AI to help me on this one.
  3 个评论
显示 1更早的评论
Christopher Stapels
Christopher Stapels 2025-5-9
Have you tried the MATLAB AI Chat playground? Its uses MATLAB documentation, so it tends to be a little more focused on the MATLAB language.
Chris
Chris 2025-5-9
No, just Google's AI. I'll have to check this one out; I wasn't aware of it. Thanks again.

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