# How to count classes in an array to represent them in a Dashborad
**URL:** https://discourse.nodered.org/t/how-to-count-classes-in-an-array-to-represent-them-in-a-dashborad/31253
**Category:** Dashboard
**Created:** [7 August 2020 05:59 UTC](https://discourse.nodered.org/t/how-to-count-classes-in-an-array-to-represent-them-in-a-dashborad/31253 "2020-08-07T05:59:26Z")
**Posts on this page:** 11
**Page:** 1
### Author:  [@CesarLeiton](https://discourse.nodered.org/u/CesarLeiton)
#### Post date: [7 August 2020 05:59 UTC](https://discourse.nodered.org/t/how-to-count-classes-in-an-array-to-represent-them-in-a-dashborad/31253/1 "2020-08-07T05:59:26Z")
Hello,
I have this flow and I would like to count the number of persons in each image. For each object where class ="person", I would like to count 1.
Afterwards I would like to use it for a dashboard to see it in a histogram in a dashboard.
Could you help me?
---
### Author:  [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)
#### Post date: [7 August 2020 06:28 UTC](https://discourse.nodered.org/t/how-to-count-classes-in-an-array-to-represent-them-in-a-dashborad/31253/2 "2020-08-07T06:28:39Z")
One way...
Use a function node & use the `.filter` [function](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter) to return only the entries that have this.
Any help?
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### Author:  [@dceejay](https://discourse.nodered.org/u/dceejay)
#### Post date: [7 August 2020 09:12 UTC](https://discourse.nodered.org/t/how-to-count-classes-in-an-array-to-represent-them-in-a-dashborad/31253/3 "2020-08-07T09:12:18Z")
Which, of the several tfjs nodes, is this ? - My version - node-red-contrib-tfjs-coco-ssd - creates a msg.classes property that is an array of classes and counts.
(Note : - be warned that installing two similar tfjs nodes often causes conflicts withe underlying tfjs binary so you may need to uninstall one before installing another if you choose to do that)
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### Author:  [@CesarLeiton](https://discourse.nodered.org/u/CesarLeiton)
#### Post date: [7 August 2020 12:20 UTC](https://discourse.nodered.org/t/how-to-count-classes-in-an-array-to-represent-them-in-a-dashborad/31253/4 "2020-08-07T12:20:38Z")
Thanks for your answer. I am using this "[https://flows.nodered.org/node/node-red-contrib-tensorflow](https://flows.nodered.org/node/node-red-contrib-tensorflow)" node-red-contrib-tensorflow, which gives as output these metadata: object, class, bounding box coordenates and score.
I am not sure if I should try yours. We have a flow for predicting with cocossd classes of a picture obtained from an streaming ip video. And our goal would be to show in a dashboard the number of persons vs time in the incoming pictures.
Do you think I should use node-red-contrib-tfjs-coco-ssd?
Thank you in advance,
---
### Author:  [@CesarLeiton](https://discourse.nodered.org/u/CesarLeiton)
#### Post date: [7 August 2020 12:22 UTC](https://discourse.nodered.org/t/how-to-count-classes-in-an-array-to-represent-them-in-a-dashborad/31253/5 "2020-08-07T12:22:39Z")
Thanks for your quick answer. I am a beginner with JavaScript, I have to figure out how to implement the .filter function code.
I will try and let you know if it worked.
Many thanks again,
---
### Author:  [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)
#### Post date: [7 August 2020 12:28 UTC](https://discourse.nodered.org/t/how-to-count-classes-in-an-array-to-represent-them-in-a-dashborad/31253/6 "2020-08-07T12:28:26Z")
it'll be something like...
Function node code...
```auto
var filter = "person"; //what to find - note this could come from msg.payload or anywhere!
var filtered = msg.details.filter(el => el.class == filter); //filter to elements with .class equal to filter
msg.payload = filtered; //set payload to the filtered results
return msg; //send the payload to next node
```
this will give you an array of items where class == person
If you truly only want the count then change it to this...
```auto
var filter = "person"; //what to find - note this could come from msg.payload or anywhere!
var filtered = msg.details.filter(el => el.class == filter); //filter to elements with .class equal to filter
if(filtered && filtered.count)
msg.payload = filtered.count; //set payload to the count found
else
msg.payload = 0;
return msg; //send the payload to next node
```
EDIT:
these are untested - ymmv
---
### Author:  [@CesarLeiton](https://discourse.nodered.org/u/CesarLeiton)
#### Post date: [8 August 2020 07:40 UTC](https://discourse.nodered.org/t/how-to-count-classes-in-an-array-to-represent-them-in-a-dashborad/31253/7 "2020-08-08T07:40:36Z")
Many thanks Steve! I will let you know the result 🙂
---
### Author:  [@CesarLeiton](https://discourse.nodered.org/u/CesarLeiton)
#### Post date: [8 August 2020 08:56 UTC](https://discourse.nodered.org/t/how-to-count-classes-in-an-array-to-represent-them-in-a-dashborad/31253/8 "2020-08-08T08:56:21Z")
Hello again,
I have introduced the code in a node function:
And it seems like it does not filter the elements with .class equal to filter, because I added a new node msg.details, after the function node and it still shows in the pane objects with different class type than person (boat, for example).
Regarding with the counting part. I tried as well to check it taking the information to a dashboard, but it is always showing 0, even if in the debug pane you can see that it is detecting "person".
Perhaps I am not configuring correctly the dashboard settings.
---
### Author:  [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)
#### Post date: [8 August 2020 10:46 UTC](https://discourse.nodered.org/t/how-to-count-classes-in-an-array-to-represent-them-in-a-dashborad/31253/9 "2020-08-08T10:46:14Z")
As I alluded to, it was untested code. I should have used `.length` not `.count`
Change the code to this...
```auto
var filter = "person"; //what to find - note this could come from msg.payload or anywhere!
var filtered = msg.details.filter(el => el.class == filter); //filter to elements with .class equal to filter
if(filtered && filtered.length) {
msg.payload = filtered.length; //set payload to the count found
} else {
msg.payload = 0;
}
msg.filtered = filtered; //pass the filtered array in the msg for future capabilities
return msg; //send the msg to the next node
```
NOTE: I have added the property `.filtered` to the `msg` so if you want to display the score or access the bounding box - the filtered results will be already in the msg for you (just ignore this property if not needed)
---
### Author:  [@CesarLeiton](https://discourse.nodered.org/u/CesarLeiton)
#### Post date: [8 August 2020 11:17 UTC](https://discourse.nodered.org/t/how-to-count-classes-in-an-array-to-represent-them-in-a-dashborad/31253/10 "2020-08-08T11:17:00Z")
Thank you very much! It wasvery helpful
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### Author:  [@system](https://discourse.nodered.org/u/system)
#### Post date: [7 September 2020 11:17 UTC](https://discourse.nodered.org/t/how-to-count-classes-in-an-array-to-represent-them-in-a-dashborad/31253/11 "2020-09-07T11:17:03Z")
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