# If number increases or decreases

**URL:** <https://discourse.nodered.org/t/if-number-increases-or-decreases/55420>\
**Category:** General\
**Created:** [19 December 2021 09:51 UTC](https://discourse.nodered.org/t/if-number-increases-or-decreases/55420 "2021-12-19T09:51:53Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![bigmac5753](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/bigmac5753/32/15733_2.png) [@bigmac5753](https://discourse.nodered.org/u/bigmac5753)\
**Post date:** [19 December 2021 09:51 UTC](https://discourse.nodered.org/t/if-number-increases-or-decreases/55420/1 "2021-12-19T09:51:53Z")

</div>

I have a flow that outputs a number that periodically changes. I want a node that states whether the number increased or decreased. ideally, I want a node that either:

a) outputs a msg stating the number either increased or decreased. or,  
b) has 2 outputs, one for number decreased, other for number increased

Does anyone know how this can be achieved?

TIA

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<div class="post-metadata">

**Author:** ![E1cid](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/e1cid/32/77971_2.png) [@E1cid](https://discourse.nodered.org/u/E1cid)\
**Post date:** [19 December 2021 10:07 UTC](https://discourse.nodered.org/t/if-number-increases-or-decreases/55420/2 "2021-12-19T10:07:44Z")

</div>

You would need to store the previous value and then compare to new value  
Here is an example using a function node.

```auto
[{"id":"a6ce57e9.6689e8","type":"inject","z":"c791cbc0.84f648","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"1.2","payloadType":"num","x":100,"y":1060,"wires":[["3fbc9b4c.cbba54"]]},{"id":"3fbc9b4c.cbba54","type":"function","z":"c791cbc0.84f648","name":"","func":"let prev = context.get(\"previous\") || 0;\nif( prev > msg.payload){\n msg.change = \"decrease\";\n}else if(prev < msg.payload){\n msg.change = \"increase\";\n}else{\n msg.change = \"unchanged\";\n}\ncontext.set(\"previous\", msg.payload)\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","x":320,"y":1120,"wires":[["e8823236e6e79e37"]]},{"id":"a2eef470.16b008","type":"inject","z":"c791cbc0.84f648","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"1.4","payloadType":"num","x":100,"y":1100,"wires":[["3fbc9b4c.cbba54"]]},{"id":"8029102f.62f728","type":"inject","z":"c791cbc0.84f648","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"1.6","payloadType":"num","x":100,"y":1140,"wires":[["3fbc9b4c.cbba54"]]},{"id":"e8823236e6e79e37","type":"debug","z":"c791cbc0.84f648","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","statusVal":"","statusType":"auto","x":530,"y":1100,"wires":[]},{"id":"1d5fa17768faa0ad","type":"function","z":"c791cbc0.84f648","name":"","func":"//create a look up table for sensors required and chart line name\nconst sensors = {\"201201/tempUoTwoBalco\": \"supplyTemp\", \n \"201201/tempUoThreeBalco\": \"returnTemp\"};\n//set the payload to data \nlet data = msg.payload.replace(\"NaN\", \"null\");\ntry {\n data = JSON.parse(data)\n}\ncatch(err) {\n data ={};\n}\n// set output to null\nlet temps = {};\nfor(const element of Object.values(sensors)){\n temps[element] = null;\n}\n// loop through data getting keys\nfor(const key1 in sensors){\n if( data[key1] ){ // checkif key in sensor lookup\n temps[sensors[key1]] = {}; //initialise object\n temps[sensors[key1]].payload = data[key1].value; // add payload\n temps[sensors[key1]].topic = sensors[key1]; // add topic\n }\n}\n// create return array\ntemps = Object.values(temps);\nreturn [temps];","outputs":1,"noerr":0,"initialize":"","finalize":"","x":470,"y":800,"wires":[["e8823236e6e79e37"]]},{"id":"f86aa943.42e648","type":"http request","z":"c791cbc0.84f648","name":"","method":"GET","ret":"txt","paytoqs":"body","url":"","tls":"","persist":true,"proxy":"","authType":"","x":480,"y":1040,"wires":[["e8823236e6e79e37"]]},{"id":"fb2e7c30.1a254","type":"html","z":"c791cbc0.84f648","name":"","property":"payload","outproperty":"payload","tag":"input","ret":"attr","as":"single","x":500,"y":960,"wires":[["7a1f9c4d.b6f23c","e8823236e6e79e37"]]},{"id":"f2a105a1.b216","type":"inject","z":"c791cbc0.84f648","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"{ \"201201/tempUoTwoBalco\": { \"value\": 63.1199951171875, \"route\": \"/vui/platforms/benshome/devices/201201/tempUoTwoBalco\", \"writable\": false }, \"201201/tempUoThreeBalco\": { \"value\": 74.12999725341797, \"route\": \"/vui/platforms/benshome/devices/201201/tempUoThreeBalco\", \"writable\": false }, \"201201/Oat\": { \"value\": 89.99999237060547, \"route\": \"/vui/platforms/benshome/devices/201201/Oat\", \"writable\": false }, \"201201/RmTmpSpt\": { \"value\": 79.99999237060547, \"route\": \"/vui/platforms/benshome/devices/201201/RmTmpSpt\", \"writable\": true }, \"201201/RmTmp\": { \"value\": NaN, \"route\": \"/vui/platforms/benshome/devices/201201/RmTmp\", \"writable\": false }, \"201201/UhCmd\": { \"value\": 0, \"route\": \"/vui/platforms/benshome/devices/201201/UhCmd\", \"writable\": false }, \"201201/GlblHtgDsbl\": { \"value\": 0, \"route\": \"/vui/platforms/benshome/devices/201201/GlblHtgDsbl\", \"writable\": false }}","payloadType":"str","x":310,"y":840,"wires":[["1d5fa17768faa0ad"]]},{"id":"7a1f9c4d.b6f23c","type":"function","z":"c791cbc0.84f648","name":"","func":"let cookie= 'atuserid={\"name\":\"atuserid\",\"val\":\"3160539b-a16a-456a-9537-1a363993b0a8\",\"options\":{\"end\":\"2023-01-03T15:46:25.274Z\",\"path\":\"/\"}}; public=h8ha1a8ajdhjotpnr2nmsg3hu5; atauthority={\"name\":\"atauthority\",\"val\":{\"authority_name\":\"cnil\",\"visitor_mode\":\"exempt\"},\"options\":{\"end\":\"2023-01-19T09:33:17.178Z\",\"path\":\"/\"}}';\n\nmsg.headers = {};\nmsg.headers['user-agent'] = 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/xx.0.xx.xx Safari/537.36';\nmsg.headers['accept-language']= 'fr-FR,fr;q=0.9,en-US;q=0.8,en;q=0.7,de;q=0.6';\nmsg.headers['cache-control'] = 'max-age=0';\nmsg.headers['content-type']= 'application/x-www-form-urlencoded';\nmsg.cookies = msg.responseCookies;\ndelete msg.responseCookies;\n\n\n\nlet data = msg.payload.slice(0,10).reduce((obj,e) => {obj[e.id] = e.value; return obj},{})\nnode.warn(data)\n\nmsg.url='https://www.prix-carburants.gouv.fr';\n\n msg.payload = data;\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","x":340,"y":1000,"wires":[["f86aa943.42e648"]]},{"id":"ba593c35.0e7ad8","type":"http request","z":"c791cbc0.84f648","name":"","method":"GET","ret":"txt","paytoqs":"body","url":"","tls":"","persist":true,"proxy":"","authType":"","x":420,"y":900,"wires":[["fb2e7c30.1a254"]]},{"id":"c3db1f81.260b9","type":"inject","z":"c791cbc0.84f648","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":160,"y":1000,"wires":[["7a1f9c4d.b6f23c"]]},{"id":"bb2f08f3.8ddad8","type":"function","z":"c791cbc0.84f648","name":"","func":"msg.headers = {};\nmsg.headers['user-agent'] = 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/xx.0.xx.xx Safari/537.36';\nmsg.headers['accept-language']= 'fr-FR,fr;q=0.9,en-US;q=0.8,en;q=0.7,de;q=0.6';\nmsg.url='https://www.prix-carburants.gouv.fr/';\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","x":350,"y":940,"wires":[["ba593c35.0e7ad8"]]},{"id":"d450f140.e9b4b","type":"inject","z":"c791cbc0.84f648","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":180,"y":940,"wires":[["bb2f08f3.8ddad8"]]}]

```

[https://nodered.org/docs/user-guide/context](https://nodered.org/docs/user-guide/context)

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<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [19 December 2021 10:09 UTC](https://discourse.nodered.org/t/if-number-increases-or-decreases/55420/3 "2021-12-19T10:09:55Z")

</div>

You can use a Switch node for this. Configure one output to pass if msg.payload \> previous value and one output for msg.payload \< previous value. If it is the same value then there will be no output.

![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/9/b/9bc45d7f25df48301cf9ee30b679b3dc1b6cf644.png)

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [17 February 2022 10:10 UTC](https://discourse.nodered.org/t/if-number-increases-or-decreases/55420/4 "2022-02-17T10:10:25Z")

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