Newbie question: openweather 5 day prediction filter (min temp value)

General
1

I'm a little bit lost here, I try to filter the lowest temp from the 5 day weather forecast to close some water valves if for example temp_min is below -5°..
Hereunder a small part (3 of 40) of the msg output from the 5 day weather forecast from openWeather API.

I just want to return all days when the (temp_min) is lower than -5° as a result. I was busy all day trying to get this result but I'm completely lost :-(.

Some insights would be appreciated.
I understand the basics of For loops and If then statements but it's really hard for me to apply this on real examples.

[
{"dt":1606489200,"main":{"temp":8.44,"feels_like":5.83,"temp_min":8.44,"temp_max":8.64,"pressure":1018}
,{"dt":1606500000,"main":{"temp":7.15,"feels_like":3.96,"temp_min":6.85,"temp_max":7.15,"pressure":1018}
,{"dt":1606510800,"main":{"temp":6.64,"feels_like":3.61,"temp_min":6.53,"temp_max":6.64,"pressure":1019}
]

2

Have a look the javascript Array.filter() method. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter

Have a play with that and see if you can work it out.

3

Hello Colin, thanks for your response and your help. I've made progress :slight_smile:
If I do this, It get the expected result. It seems that my first array was incomplete also btw..

const mintemps = [
{"dt":1606489200,"main":{"temp":8.44,"feels_like":5.83,"temp_min":8.44,"temp_max":8.64,"pressure":1018}},
{"dt":1606500000,"main":{"temp":7.15,"feels_like":3.96,"temp_min":6.85,"temp_max":7.15,"pressure":1018}},
{"dt":1606510800,"main":{"temp":6.64,"feels_like":3.61,"temp_min":6.53,"temp_max":6.64,"pressure":1019}}
]

const result = mintemps.filter(mintemps => mintemps.main.temp_min <7);

console.log(result);

Array [Object { dt: 1606500000, main: Object { temp: 7.15, feels_like: 3.96, temp_min: 6.85, temp_max: 7.15, pressure: 1018 } }, Object { dt: 1606510800, main: Object { temp: 6.64, feels_like: 3.61, temp_min: 6.53, temp_max: 6.64, pressure: 1019 } }]

4

You can also do this in the change node using JSONata expression.
e.g.

[{"id":"b0987c18.4dcc6","type":"change","z":"8d22ae29.7df6d","name":"","rules":[{"t":"set","p":"payload","pt":"msg","to":"payload[][main.temp_min < 7]","tot":"jsonata"}],"action":"","property":"","from":"","to":"","reg":false,"x":300,"y":2120,"wires":[["e8309938.fb1628"]]},{"id":"d8f3269b.a43d9","type":"inject","z":"8d22ae29.7df6d","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"[{\"dt\":1606489200,\"main\":{\"temp\":8.44,\"feels_like\":5.83,\"temp_min\":8.44,\"temp_max\":8.64,\"pressure\":1018}},{\"dt\":1606500000,\"main\":{\"temp\":7.15,\"feels_like\":3.96,\"temp_min\":6.85,\"temp_max\":7.15,\"pressure\":1018}},{\"dt\":1606510800,\"main\":{\"temp\":6.64,\"feels_like\":3.61,\"temp_min\":6.53,\"temp_max\":6.64,\"pressure\":1019}}]","payloadType":"json","x":130,"y":2120,"wires":[["b0987c18.4dcc6","e8309938.fb1628"]]},{"id":"e8309938.fb1628","type":"debug","z":"8d22ae29.7df6d","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","statusVal":"","statusType":"auto","x":490,"y":2040,"wires":[]}]

this will return all array items where temp_min is less than 7.

5

If you wanted just the timestamps back then if you then use .map() on the filtered result you can return just an array of timestamps.

6

I'll try that to Cid, thank you.

7

I'll have a look at .map () too. thank you (again :slight_smile:

8

If you just want the timestamps the Jsonata expression would be payload[][main.temp_min < 7].dt

9

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