Temperature tendency

[Thomas]

Hello
Do you have any idea or experience how to calculate outside temperature tendency?
I'm thinking about linear regression for last 1 hr where the angle of the regression line is the tendency.
Or simply sum (dT) for the last 60 minutes (maybe it's the same value).

Have you found any better algorithm?

[admin]

What is the use case for this? Why not use weather forecast for this? yr.no XML forecast has temperature values for each 6 hours which should be enough for most cases.

[Tokatubs]

What is the use case for this? Why not use weather forecast for this? yr.no XML forecast has temperature values for each 6 hours which should be enough for most cases.

Is this what you refer to Admin?

https://forum.logicmachine.net/showthrea...1#pid11521

[admin]

Yes, but it won't work over plain HTTP. Change socket.http to ssl.https and http to https.

[Thomas]

The idea is to show the tendency in visu as simple as possible. Just arrow up or down. The question is about best low-pass filter setting.
What algorithm is mostly used?

[Erwin van der Zwart]

Hi,

If you just need arrow up/down then comparing last value with new value is enough in my opinion, when last value is 19 and new is > then last value then tendency is "UP" and when new value is < last value then tendency is "DOWN", to make it more stable / less fluctuating you could make a average of last 5 values and compare it with new value.

BR,

Erwin

[admin]

You can use simple IIR filter to calculate average values:

Code:

ALPHA = 0.1 -- between 0 and 1, adjust as needed

function iir_filter(val, avg)
  return val * ALPHA + avg * (1 - ALPHA)
end

avg = 0
for val = 1, 10 do
  avg = iir_filter(val, avg)
end

log(avg)