# Combining arrays into an array of arrays OR removing empty string elements from an array

**URL:** <https://discourse.nodered.org/t/combining-arrays-into-an-array-of-arrays-or-removing-empty-string-elements-from-an-array/80578>\
**Category:** General\
**Created:** [15 August 2023 11:37 UTC](https://discourse.nodered.org/t/combining-arrays-into-an-array-of-arrays-or-removing-empty-string-elements-from-an-array/80578 "2023-08-15T11:37:00Z")\
**Posts on this page:** 9\
**Page:** 1

<div class="post-metadata">

**Author:** ![gettmad](https://avatars.discourse-cdn.com/v4/letter/g/48db29/32.png) [@gettmad](https://discourse.nodered.org/u/gettmad)\
**Post date:** [15 August 2023 11:37 UTC](https://discourse.nodered.org/t/combining-arrays-into-an-array-of-arrays-or-removing-empty-string-elements-from-an-array/80578/1 "2023-08-15T11:37:00Z")

</div>

Hello,

This is more of a coding question then a direct concern with Node-RED however I would greatly appreciate the help.

I am using Node-RED to publish topics to MQTT from a report. As a result I am required to manipulate the data in order to obtain a properly displayed format in MQTT Explorer.

Right now, I have successfully manipulated the data & it comes up correctly in MQTT Explorer however I am trying to implement a 'Delete' function which clears all topics from the client. In order to do this I now need to change the way my data is being Published which requires it to be in either an Array of Arrays OR I must remove the empty string elements from some of the arrays.

This is the code for my publish function:

```auto
var versionInf = msg.payload;
flow.set('versionInf', msg.payload);

for (var b = 0; b < versionInf.length; b+=2) {
    var topic = 'FANUC Robot/Version Information/' + versionInf[b]; // Append the index to make the topic unique
    var payload = versionInf[b+1]
    node.send({ topic: topic, payload: payload });
}

return null

```

The data enters the function node (publish node) in the following format:

```auto
["Update Version "," None"]

```

However when I use the join node once again to attempt to combine the data into an array of arrays, some of the contents give 3 element array while others give a 2 element array as follow:

```auto
["DCS"," "," V3.5.12"]

```

I would like to either: Use a function which removes of the empty string elements within the array or to use a function which combines the arrays into a single array without using the join node which returns some 3 element arrays.

Thank you for your assistance. I can provide further details upon request.

---

<div class="post-metadata">

**Author:** ![zenofmud](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/zenofmud/32/316_2.png) [@zenofmud](https://discourse.nodered.org/u/zenofmud)\
**Post date:** [15 August 2023 14:13 UTC](https://discourse.nodered.org/t/combining-arrays-into-an-array-of-arrays-or-removing-empty-string-elements-from-an-array/80578/2 "2023-08-15T14:13:20Z")

</div>

> [@gettmad](#):
>
> however I am trying to implement a 'Delete' function which clears all topics from the client.

Some device `publishes` a msg that has a topic and data. The `broker` then sends that msg to any device that has `subscribed` to that topic. If you only want to remove that msg from teh broker, you need to publish another msg with that topic and a zero byte payload.

If you want to learn more about MQTT then see this tutorial [MQTT Essentials - All Core Concepts Explained](https://www.hivemq.com/mqtt-essentials/)

---

<div class="post-metadata">

**Author:** ![gettmad](https://avatars.discourse-cdn.com/v4/letter/g/48db29/32.png) [@gettmad](https://discourse.nodered.org/u/gettmad)\
**Post date:** [15 August 2023 14:26 UTC](https://discourse.nodered.org/t/combining-arrays-into-an-array-of-arrays-or-removing-empty-string-elements-from-an-array/80578/3 "2023-08-15T14:26:54Z")

</div>

Hello Zenofmud,

I am indeed deleting the topics correctly by sending an empty payload with QoS 0 and retain set to true.

The main issue lies in the organization of my data. I am unaware of how to use an iterative for loop to combine several arrays into either and array of arrays and/or one big array OR how to clear empty elements of the individual arrays so that I can get it into the form i desire.

Thanks for your response.

---

<div class="post-metadata">

**Author:** ![zenofmud](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/zenofmud/32/316_2.png) [@zenofmud](https://discourse.nodered.org/u/zenofmud)\
**Post date:** [15 August 2023 14:30 UTC](https://discourse.nodered.org/t/combining-arrays-into-an-array-of-arrays-or-removing-empty-string-elements-from-an-array/80578/4 "2023-08-15T14:30:37Z")

</div>

When you say several arrays can you give me an example of the data?

Actually can you provide the flow with some test data that shows the issue

---

<div class="post-metadata">

**Author:** ![gettmad](https://avatars.discourse-cdn.com/v4/letter/g/48db29/32.png) [@gettmad](https://discourse.nodered.org/u/gettmad)\
**Post date:** [16 August 2023 18:44 UTC](https://discourse.nodered.org/t/combining-arrays-into-an-array-of-arrays-or-removing-empty-string-elements-from-an-array/80578/5 "2023-08-16T18:44:10Z")

</div>

Here is the requested flow & the text file I am pulling the data from.

```auto
[
    {
        "id": "743cc0234f1851f1",
        "type": "tab",
        "label": "Flow 1",
        "disabled": false,
        "info": "",
        "env": []
    },
    {
        "id": "f51f30daa9fe8fb7",
        "type": "group",
        "z": "743cc0234f1851f1",
        "name": "MANUAL TRIGGER",
        "style": {
            "stroke": "#ff0000",
            "fill": "#ffffff",
            "label": true,
            "label-position": "n",
            "color": "#000000"
        },
        "nodes": [
            "3f781378483a51f6",
            "182a62f9469aa974",
            "99e9e83ff0d516e3",
            "e345179f4c3923e0"
        ],
        "x": 254,
        "y": 109,
        "w": 192,
        "h": 157
    },
    {
        "id": "3f781378483a51f6",
        "type": "file in",
        "z": "743cc0234f1851f1",
        "g": "f51f30daa9fe8fb7",
        "name": "TEST",
        "filename": "C:\\Users\\PC\\Documents\\TEST.txt",
        "filenameType": "str",
        "format": "utf8",
        "chunk": false,
        "sendError": false,
        "encoding": "none",
        "allProps": false,
        "x": 350,
        "y": 175,
        "wires": [
            [
                "99e9e83ff0d516e3"
            ]
        ]
    },
    {
        "id": "182a62f9469aa974",
        "type": "inject",
        "z": "743cc0234f1851f1",
        "g": "f51f30daa9fe8fb7",
        "name": "",
        "props": [
            {
                "p": "payload"
            },
            {
                "p": "topic",
                "vt": "str"
            }
        ],
        "repeat": "",
        "crontab": "",
        "once": false,
        "onceDelay": 0.1,
        "topic": "",
        "payload": "",
        "payloadType": "date",
        "x": 360,
        "y": 150,
        "wires": [
            [
                "3f781378483a51f6"
            ]
        ]
    },
    {
        "id": "99e9e83ff0d516e3",
        "type": "split",
        "z": "743cc0234f1851f1",
        "g": "f51f30daa9fe8fb7",
        "name": "",
        "splt": "\\n",
        "spltType": "str",
        "arraySplt": 1,
        "arraySpltType": "len",
        "stream": false,
        "addname": "",
        "x": 370,
        "y": 200,
        "wires": [
            [
                "e345179f4c3923e0"
            ]
        ]
    },
    {
        "id": "e345179f4c3923e0",
        "type": "join",
        "z": "743cc0234f1851f1",
        "g": "f51f30daa9fe8fb7",
        "name": "",
        "mode": "custom",
        "build": "array",
        "property": "payload",
        "propertyType": "msg",
        "key": "topic",
        "joiner": " ",
        "joinerType": "str",
        "accumulate": false,
        "timeout": "",
        "count": "",
        "reduceRight": false,
        "reduceExp": "",
        "reduceInit": "",
        "reduceInitType": "num",
        "reduceFixup": "",
        "x": 370,
        "y": 225,
        "wires": [
            [
                "d1065ab4c4fd42cd"
            ]
        ]
    },
    {
        "id": "3331fd4615f9b442",
        "type": "function",
        "z": "743cc0234f1851f1",
        "name": "Publish",
        "func": "var versionInf = msg.payload;\nflow.set('versionInf', msg.payload);\n\nfor (var b = 0; b < versionInf.length; b++) {\n var topic = 'TEST/Information/' + versionInf[b][0]; // Append the index to make the topic unique\n var payload = versionInf[b][1]\n node.send({ topic: topic, payload: payload });\n \n }\n\nreturn null",
        "outputs": 1,
        "timeout": "",
        "noerr": 0,
        "initialize": "",
        "finalize": "",
        "libs": [],
        "x": 1275,
        "y": 225,
        "wires": [
            [
                "f8934eaf1f046d87"
            ]
        ]
    },
    {
        "id": "d1065ab4c4fd42cd",
        "type": "split",
        "z": "743cc0234f1851f1",
        "name": "Split to new line",
        "splt": "\\n",
        "spltType": "str",
        "arraySplt": 1,
        "arraySpltType": "len",
        "stream": false,
        "addname": "",
        "x": 580,
        "y": 225,
        "wires": [
            [
                "03ff8d8ce3dbbe69"
            ]
        ]
    },
    {
        "id": "6cfe2b4b8cc16828",
        "type": "join",
        "z": "743cc0234f1851f1",
        "name": "",
        "mode": "custom",
        "build": "array",
        "property": "payload",
        "propertyType": "msg",
        "key": "topic",
        "joiner": "\\n",
        "joinerType": "str",
        "accumulate": false,
        "timeout": "",
        "count": "",
        "reduceRight": false,
        "reduceExp": "",
        "reduceInit": "",
        "reduceInitType": "num",
        "reduceFixup": "",
        "x": 1090,
        "y": 225,
        "wires": [
            [
                "c3259815b458bb9b"
            ]
        ]
    },
    {
        "id": "fba61b48e8d791d5",
        "type": "function",
        "z": "743cc0234f1851f1",
        "name": "Replacing ",
        "func": "msg.payload = msg.payload.split(' ').join(':');\nmsg.payload = msg.payload.split(' ').join(':');\nreturn msg;",
        "outputs": 1,
        "timeout": 0,
        "noerr": 0,
        "initialize": "",
        "finalize": "",
        "libs": [],
        "x": 790,
        "y": 225,
        "wires": [
            [
                "0209096a4abcaad1"
            ]
        ]
    },
    {
        "id": "0209096a4abcaad1",
        "type": "split",
        "z": "743cc0234f1851f1",
        "name": "Split over : ",
        "splt": ":",
        "spltType": "str",
        "arraySplt": 1,
        "arraySpltType": "len",
        "stream": false,
        "addname": "",
        "x": 950,
        "y": 225,
        "wires": [
            [
                "6cfe2b4b8cc16828"
            ]
        ]
    },
    {
        "id": "03ff8d8ce3dbbe69",
        "type": "function",
        "z": "743cc0234f1851f1",
        "name": "Replacing ",
        "func": "msg.payload = msg.payload.split(' :').join(':');\nmsg.payload = msg.payload.split('/').join('-');\nreturn msg;",
        "outputs": 1,
        "timeout": 0,
        "noerr": 0,
        "initialize": "",
        "finalize": "",
        "libs": [],
        "x": 595,
        "y": 250,
        "wires": [
            [
                "fba61b48e8d791d5"
            ]
        ]
    },
    {
        "id": "c3259815b458bb9b",
        "type": "join",
        "z": "743cc0234f1851f1",
        "name": "",
        "mode": "custom",
        "build": "array",
        "property": "payload",
        "propertyType": "msg",
        "key": "topic",
        "joiner": "\\n",
        "joinerType": "str",
        "accumulate": false,
        "timeout": "",
        "count": "",
        "reduceRight": false,
        "reduceExp": "",
        "reduceInit": "",
        "reduceInitType": "num",
        "reduceFixup": "",
        "x": 1090,
        "y": 250,
        "wires": [
            [
                "3331fd4615f9b442",
                "70df2e550e8e6350"
            ]
        ]
    },
    {
        "id": "70df2e550e8e6350",
        "type": "debug",
        "z": "743cc0234f1851f1",
        "name": "debug 387",
        "active": true,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "false",
        "statusVal": "",
        "statusType": "auto",
        "x": 1170,
        "y": 375,
        "wires": []
    },
    {
        "id": "f8934eaf1f046d87",
        "type": "mqtt out",
        "z": "743cc0234f1851f1",
        "name": "",
        "topic": "",
        "qos": "",
        "retain": "",
        "respTopic": "",
        "contentType": "",
        "userProps": "",
        "correl": "",
        "expiry": "",
        "broker": "c2f9ab517722afa0",
        "x": 1425,
        "y": 225,
        "wires": []
    },
    {
        "id": "c2f9ab517722afa0",
        "type": "mqtt-broker",
        "name": "",
        "broker": "127.0.0.1",
        "port": "1883",
        "clientid": "MQTT Explorer",
        "autoConnect": true,
        "usetls": false,
        "protocolVersion": "4",
        "keepalive": "60",
        "cleansession": true,
        "autoUnsubscribe": true,
        "birthTopic": "",
        "birthQos": "0",
        "birthPayload": "",
        "birthMsg": {},
        "closeTopic": "",
        "closeQos": "0",
        "closePayload": "",
        "closeMsg": {},
        "willTopic": "",
        "willQos": "0",
        "willPayload": "",
        "willMsg": {},
        "userProps": "",
        "sessionExpiry": ""
    }
]

```

[TEST.txt](https://discourse.nodered.org/uploads/short-url/ySqmQKfm8a0CcT6iqrCAtJEAFc1.txt) (623 Bytes)

Let me know if you have further requests/questions regarding the flow or the desired behavior.

Thanks,

Jordan Madgett

---

<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:** [16 August 2023 20:24 UTC](https://discourse.nodered.org/t/combining-arrays-into-an-array-of-arrays-or-removing-empty-string-elements-from-an-array/80578/6 "2023-08-16T20:24:11Z")

</div>

That is one messed up text file format, not much consistency.  
This example may help

```auto
[{"id":"182a62f9469aa974","type":"inject","z":"743cc0234f1851f1","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":360,"y":150,"wires":[["e4bf02867c4a6690"]]},{"id":"e4bf02867c4a6690","type":"template","z":"743cc0234f1851f1","name":"","field":"payload","fieldType":"msg","format":"handlebars","syntax":"mustache","template":"LR HandlingTool 4324/543\nS/W Serial No. : 6243 \nController ID : F888 \nRobot No. : A8888 \nManufacturing ID : \nAA Rate abcd/7F, CGES \nLT Tate 200iD/7F V1.30D/33 \nAAaor AA : V10.03 \nTart. DDD. Parameter: V3.00\nANT. Mot. Parameter : V3.00\nDCS : V3.5.12\nSt0p pattern : A\nSoftware Edition No.: D8.SSP/34 \nUpdate Version : No\nCustomization Ver. : No\nRoot Version : V8.30226 \nBoot MONITOR : V8.30P/31\nTeach Peadant : 8AAF/11A\nBrdsser Plugins : V2.34222\nTF Dore Firmware : V2.304/31\nMedia from AAA 12/36/2034","output":"str","x":360,"y":180,"wires":[["d1065ab4c4fd42cd"]]},{"id":"d1065ab4c4fd42cd","type":"split","z":"743cc0234f1851f1","name":"Split to new line","splt":"\\n","spltType":"str","arraySplt":1,"arraySpltType":"len","stream":false,"addname":"","x":560,"y":180,"wires":[["03ff8d8ce3dbbe69"]]},{"id":"03ff8d8ce3dbbe69","type":"function","z":"743cc0234f1851f1","name":"Replacing ","func":"msg.payload = msg.payload.replace(/:/g, \" \")\nmsg.payload = msg.payload.split(/\\s+\\s+/)\nmsg.topic = \"TEST/Information/\" + msg.payload[0].trim()\nmsg.payload = msg.payload[1].trim()\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":720,"y":180,"wires":[["70df2e550e8e6350"]]},{"id":"70df2e550e8e6350","type":"debug","z":"743cc0234f1851f1","name":"debug 387","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":770,"y":240,"wires":[]}]

```

I have simulated the file read with a template node, as it makes life easier when sharing flow examples.

---

<div class="post-metadata">

**Author:** ![gettmad](https://avatars.discourse-cdn.com/v4/letter/g/48db29/32.png) [@gettmad](https://discourse.nodered.org/u/gettmad)\
**Post date:** [17 August 2023 11:42 UTC](https://discourse.nodered.org/t/combining-arrays-into-an-array-of-arrays-or-removing-empty-string-elements-from-an-array/80578/7 "2023-08-17T11:42:36Z")

</div>

Thanks E1cid.

You sure are right, however unfortunately I do not have control over its format.

This does indeed help give me some ideas however the way I am looking to 'delete' the MQTT topics basically requires me to have my data in an array format. I am looking to split the data, left side vs right side (you could say over the ':' however this trait is not consistent). This is why I was looking to combine them into an array of arrays and to remove of the empty strings.

I am quite new to the scene, are you aware of how to recursively remove of empty string elements within arrays?

I appreciate your help! You triggered some ideas & I will keep slugging. I am tampering with lots of data which I have no control over in order to cleanly publish it to MQTT and to also be able to 'delete' it from MQTT on a timed cycle.

---

<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:** [17 August 2023 13:27 UTC](https://discourse.nodered.org/t/combining-arrays-into-an-array-of-arrays-or-removing-empty-string-elements-from-an-array/80578/8 "2023-08-17T13:27:42Z")

</div>

if this is not correct you need to give what outputs you want and what will be skipped, so we are clear.

```auto
[{"id":"182a62f9469aa974","type":"inject","z":"743cc0234f1851f1","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":360,"y":150,"wires":[["e4bf02867c4a6690"]]},{"id":"e4bf02867c4a6690","type":"template","z":"743cc0234f1851f1","name":"","field":"payload","fieldType":"msg","format":"handlebars","syntax":"mustache","template":"LR HandlingTool 4324/543\nS/W Serial No. : 6243 \nController ID : F888 \nRobot No. : A8888 \nManufacturing ID : \nAA Rate abcd/7F, CGES \nLT Tate 200iD/7F V1.30D/33 \nAAaor AA : V10.03 \nTart. DDD. Parameter: V3.00\nANT. Mot. Parameter : V3.00\nDCS : V3.5.12\nSt0p pattern : A\nSoftware Edition No.: D8.SSP/34 \nUpdate Version : No\nCustomization Ver. : No\nRoot Version : V8.30226 \nBoot MONITOR : V8.30P/31\nTeach Peadant : 8AAF/11A\nBrdsser Plugins : V2.34222\nTF Dore Firmware : V2.304/31\nMedia from AAA 12/36/2034","output":"str","x":360,"y":180,"wires":[["d1065ab4c4fd42cd"]]},{"id":"d1065ab4c4fd42cd","type":"split","z":"743cc0234f1851f1","name":"Split to new line","splt":"\\n","spltType":"str","arraySplt":1,"arraySpltType":"len","stream":false,"addname":"","x":560,"y":180,"wires":[["03ff8d8ce3dbbe69"]]},{"id":"03ff8d8ce3dbbe69","type":"function","z":"743cc0234f1851f1","name":"Replacing ","func":"msg.payload = msg.payload.replace(/:/g, \" \")\nmsg.payload = msg.payload.split(/\\s+\\s+/)\nmsg.topic = \"TEST/Information/\" + msg.payload[0].trim()\nmsg.payload = msg.payload[1].trim()\nif(msg.payload == \"\"){\n msg = null;\n}\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":720,"y":180,"wires":[["70df2e550e8e6350"]]},{"id":"70df2e550e8e6350","type":"debug","z":"743cc0234f1851f1","name":"debug 387","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":770,"y":240,"wires":[]}]

```

---

<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:** [16 October 2023 13:28 UTC](https://discourse.nodered.org/t/combining-arrays-into-an-array-of-arrays-or-removing-empty-string-elements-from-an-array/80578/9 "2023-10-16T13:28:23Z")

</div>

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