# Chart can't display several columns in table

**URL:** <https://community.influxdata.com/t/chart-cant-display-several-columns-in-table/15359>\
**Category:** Dashboards\
**Tags:** influxdb, flux\
**Created:** [July 23, 2020, 12:49pm UTC](https://community.influxdata.com/t/chart-cant-display-several-columns-in-table/15359 "2020-07-23T12:49:04Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![asmith](https://sea1.discourse-cdn.com/flex023/user_avatar/community.influxdata.com/asmith/32/8251_2.png) [@asmith](https://community.influxdata.com/u/asmith)\
**Post date:** [July 23, 2020, 12:49pm UTC](https://community.influxdata.com/t/chart-cant-display-several-columns-in-table/15359/1 "2020-07-23T12:49:04Z")

</div>

I have a \_value field and using map() have created an additional field (\_value\_2)  
The resulting table looks like …

|\_time|\_value|\_value\_2|  
|13:02:39|12.5|0.015|  
|13:02:40|18.5|0.033|  
|13:02:41|21.5|0.055|  
|13:02:42|20|0.075|  
|13:02:43|22|0.097|

But only **\_value** appears on the chart.

The chart obviously defaults to displaying \_value. But when you click on the option you can select to display \_value\_2. But you can’t select both. Surely users are going to want to do this?

The code I’m using is…

> from(bucket: “Power\_Meter”)  
> |\> range(start: v.timeRangeStart, stop: v.timeRangeStop)  
> |\> filter(fn: (r) =\> r.\_field =~ /KWH/)  
> |\> map(fn: (r) =\> ({ r with \_value\_2: r.\_value /1000.0 }))  
> |\> increase(columns: [“\_value\_2”])  
> |\> difference(nonNegative: false, columns: [“\_value”])  
> |\> keep(columns: [“\_value\_2”, “\_value”, “\_time”])

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<div class="post-metadata">

**Author:** ![Anaisdg](https://sea1.discourse-cdn.com/flex023/user_avatar/community.influxdata.com/anaisdg/32/6401_2.png) [@Anaisdg](https://community.influxdata.com/u/Anaisdg)\
**Post date:** [July 24, 2020, 7:59pm UTC](https://community.influxdata.com/t/chart-cant-display-several-columns-in-table/15359/2 "2020-07-24T19:59:23Z")

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Hello @asmith,  
Welcome! Yes this is a major shift/difference between InfluxQL and Flux.  
This issue is related:

> <https://github.com/influxdata/flux/issues/2539>
>
> Every now and then, I run into a use case where it would be really useful to hav…e the ability to unpivot data. For example, I defined this custom \`minMaxMean()\` function that uses \`reduce()\` to output the min, max, and mean values for each table. The issue is that, as-is, I can't 1) visualize the results in the UI or 2) write them back to the db because the output schema doesn't meet the requirements for writing back into InfluxDB.
> 
> \`\`\`js
> import "experimental"
> 
> minMaxMean = (tables=\<-) =\>
> tables
> |\> reduce(
> identity: {count: 0, sum: 0.0, min: 0.0, max: 0.0, mean:0.0},
> fn: (r, accumulator) =\> ({ r with
> count: accumulator.count + 1,
> sum: r.\_value + accumulator.sum,
> min: if accumulator.count == 0 then r.\_value else if r.\_value \< accumulator.min then r.\_value else accumulator.min,
> max: if accumulator.count == 0 then r.\_value else if r.\_value \> accumulator.max then r.\_value else accumulator.max,
> mean: if accumulator.count == 0 then r.\_value else (r.\_value + accumulator.sum) / float(v: accumulator.count + 1)
> })
> )
> |\> drop(columns: \["count", "sum"\])
> \`\`\`
> 
> To accomplish those things, I have to create multiple filtered streams, then union them back together:
> 
> \`\`\`js
> data = from(bucket: v.bucket)
> |\> range(start: v.timeRangeStart, stop: v.timeRangeStop)
> |\> filter(fn: (r) =\> r.\_measurement == "mem")
> |\> filter(fn: (r) =\> r.\_field == "used\_percent")
> |\> window(every: v.windowPeriod)
> |\> minMaxMean()
> |\> duplicate(column: "\_stop", as: "\_time")
> |\> window(every: inf)
> 
> min = data |\> map(fn: (r) =\> ({r with \_value: r.min, \_metricType: "min"})) |\> drop(columns: \["max", "mean"\])
> max = data |\> map(fn: (r) =\> ({r with \_value: r.max, \_metricType: "max"})) |\> drop(columns: \["min", "mean"\])
> mean = data |\> map(fn: (r) =\> ({r with \_value: r.mean, \_metricType: "mean"})) |\> drop(columns: \["min", "max"\])
> 
> union(tables: \[min, max, mean\])
> |\> experimental.group(columns: \["\_metricType"\], mode: "extend")
> \`\`\`
> 
> This could be simplified with an \`unpivot()\` function.
> 
> \`\`\`
> unpivot(
> columns: \["col1", "col2", "col3"\],
> columnDst: "\_metricType",
> valueDst: "\_value"
> )
> \`\`\`
> 
> So given the following input data:
> 
> | \_time | col1 | col2 | col3 |
> | ----- | ---- | ---- | ---- |
> | 0001 | val1.1 | val2.1 | val3.1 |
> | 0002 | val1.2 | val2.2 | val3.2 |
> | 0003 | val1.3 | val2.3 | val3.3 |
> 
> \`unpivot()\` would output:
> 
> | \_time | \_metricType | \_value |
> | ----- | ----------- | ------ | 
> | 0001 | col1 | val1.1 |
> | 0001 | col2 | val2.1 |
> | 0001 | col3 | val3.1 |
> | 0002 | col1 | val1.2 |
> | 0002 | col2 | val2.2 |
> | 0002 | col3 | val3.2 |
> | 0003 | col1 | val1.3 |
> | 0003 | col2 | val2.3 |
> | 0003 | col3 | val3.3 |

However, here is a workaround:

```auto
data = from(bucket: "Power_Meter")
 |> range(start: v.timeRangeStart, stop: v.timeRangeStop)
 |> filter(fn: (r) => r._field =~ /KWH/)
value_1 = data |> difference(nonNegative: false)
value_2 = data
 |> map(fn: (r) => ({ r with
   _value: r._value / 1000.0,
   _field: "KWH/1k"
 }))
 |> increase()
union(tables: [value_1, value_2])

```

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<div class="post-metadata">

**Author:** ![asmith](https://sea1.discourse-cdn.com/flex023/user_avatar/community.influxdata.com/asmith/32/8251_2.png) [@asmith](https://community.influxdata.com/u/asmith)\
**Post date:** [July 24, 2020, 8:39pm UTC](https://community.influxdata.com/t/chart-cant-display-several-columns-in-table/15359/3 "2020-07-24T20:39:44Z")

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Yes I can see what you are doing and I wondered how to do it.

Thanks so much!  
That trick of using the ‘data’ variable twice is very very useful.

Can different cells share the same ‘data’ variable?

That way I can read ‘data’ once, but can have different cells which display different aspects of it.

Also I would like to up-vote the need for an unpivot() function.

Unpivot() is EXACTLY what I searched for and would be a much more elegant way to manipulate the table.

Better still, a chart should be able to display multiple columns!

That would deliver such powerful functionality no?

---

<div class="post-metadata">

**Author:** ![asmith](https://sea1.discourse-cdn.com/flex023/user_avatar/community.influxdata.com/asmith/32/8251_2.png) [@asmith](https://community.influxdata.com/u/asmith)\
**Post date:** [August 4, 2020, 10:25am UTC](https://community.influxdata.com/t/chart-cant-display-several-columns-in-table/15359/4 "2020-08-04T10:25:51Z")

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Hi @Anaisdg, I’m still very much interested in my follow-on question …  
“Can different cells share the same ‘data’ variable”?

The use case :  
Within my dash I have 10 cells. Each cell queries the same time range with the same tags and filters for different variables.  
I believe it would be more efficient to query all the data once. And then each cell only has to filter data already retrieved and in the ‘data’ variable.

Would this work? Or is the data variable on the server not the client?

Does that makes sense?

Cheers

Andrew