Handling Variables with Same Name in Aggregation Functions

[younes199511]

Hi everyone,
I'm currently working with eKuiper and I have a question regarding handling variables with the same name when using aggregation functions. The goal is to find a way to filter data of the same variable name to avoid incorrect results.
For example, let's say I have two events with a variable named "temperature" and I want to calculate the average temperature across both events. However, when I use the aggregation function, it treats both "temperature" variables as the same, leading to incorrect results.

In the following graph rule, i try to compare the average of two temperatures (with same name Temperature) collected from two different devices using EdgeX Foundry but couldn't find a way to filter the inputs of each AVG function.

{
    "id": "rule1Graph",
    "name": "rule1",
    "graph": {
        "nodes": {
            "demo": {
                "type": "source",
                "nodeType": "edgex",
                "props": {
                    "format": "json"
                }
            },
            "compFilter": {
                "type": "operator",
                "nodeType": "filter",
                "props": {
                    "expr": "(`Temperature` != nil AND meta(`Temperature`->deviceName)=\"Modbus-1\") or (`Temperature` != nil AND meta(`Temperature`->deviceName)=\"Modbus-2\")"
                }
            },
            "window": {
                "type": "operator",
                "nodeType": "window",
                "props": {
                    "type": "tumblingwindow",
                    "unit": "ss",
                    "size": 30
                }
            },
            "avgfunc": {
                "type": "operator",
                "nodeType": "aggfunc",
                "props": {
                    "expr": "cast(avg(Temperature) > avg(Temperature), \"boolean\") as comp_result"
                }
            },
            "pick": {
                "type": "operator",
                "nodeType": "pick",
                "props": {
                    "fields": [
                        "comp_result"
                    ]
                }
            },
            "logOut": {
                "type": "sink",
                "nodeType": "log",
                "props": {}
            },
            "edgexOut": {
                "type": "sink",
                "nodeType": "edgex",
                "props": {
                    "connectionSelector": "edgex.redisMsgBus",
                    "protocol": "redis",
                    "server": "localhost",
                    "port": 6379,
                    "topic": "edgex/rules-events",
                    "type": "redis",
                    "messageType": "event",
                    "contentType": "application/json",
                    "deviceName": "ekuiper",
                    "profileName": "ekuiper"
                }
            }
        },
        "topo": {
            "sources": [
                "demo"
            ],
            "edges": {
                "demo": [
                    "compFilter"
                ],
                "compFilter": [
                    "window"
                ],
                "window": [
                    "avgfunc"
                ],
                "avgfunc": [
                    "pick"
                ],
                "pick": [
                    "logOut",
                    "edgexOut"
                ]
            }
        }
    }
}

Thank you for your help

[younes199511]

Hello everyone,
I've posted a question regarding handling variables with same name in aggregation functions but haven't received any responses yet. I would really appreciate any guidance or assistance on this matter. If anyone has insights or suggestions, I'd be grateful for your input.
Thank you in advance for your help!

[ngjaying]

Sorry that we forgot to take a look at this. It looks like you have Temperature from two devices. I assume they are in different message, correct? {Temperature: 12, device: 1} then {Temperature: 13, device: 2}. Can you do a pick to rename them right after the source node demo.

       "renamePick": {
              "type": "operator",
              "nodeType": "pick",
              "props": {
                  "fields": [
                      "case when meta(`Temperature`->deviceName)=\"Modbus-1\") then Temperature end as temp1",
                      "case when meta(`Temperature`->deviceName)=\"Modbus-2\") then Temperature end as temp2"
                  ]
              }
          },

Then use temp1 and temp2 in the following node.

[younes199511]

Thank you for the solution! It worked like a charm and solved my problem. I really appreciate your help. Thanks again!

[ngjaying]

My pleasure. Sorry for the delay.