# Displaying forecasted data value on time series chart

**URL:** <https://forum.inductiveautomation.com/t/displaying-forecasted-data-value-on-time-series-chart/108685>\
**Category:** Ignition\
**Tags:** perspective, ignition81\
**Created:** [July 18, 2025, 7:59pm UTC](https://forum.inductiveautomation.com/t/displaying-forecasted-data-value-on-time-series-chart/108685 "2025-07-18T19:59:14Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![mjohnson0238](https://avatars.discourse-cdn.com/v4/letter/m/4bbf92/32.png) [@mjohnson0238](https://forum.inductiveautomation.com/u/mjohnson0238)\
**Post date:** [July 18, 2025, 7:59pm UTC](https://forum.inductiveautomation.com/t/displaying-forecasted-data-value-on-time-series-chart/108685/1 "2025-07-18T19:59:14Z")

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In perspective we have a Time Series chart displaying historical tag data:

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/7/2/720f2572e246e6d8f93fad8a446544a6a4cf2df5.png)  
Its show 10 days, then does a forecasted 24hrs. how can I show what the forecasted value would be?  
Here is how we are transforming the data on the chart to show forecasting:

```python
def transform(self, value, quality, timestamp):
	from java.util import Date
	from java.sql import Timestamp
	
	headers = system.dataset.getColumnHeaders(value)
	value = list(system.dataset.toPyDataSet(value))
	finalTime = system.date.parse(value[-1][0])
	initTime = system.date.parse(value[-338][0])
	init = value[-338][1]
	final = value[-1][1]
	rate = (final-init)/(1.0*system.date.hoursBetween(initTime, finalTime))
	newTime = Timestamp(system.date.addDays(finalTime, 1).getTime())
	new = long(final + (rate * 24))
	value.append([newTime, new])
	return system.dataset.toDataSet(headers, value)

```

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<div class="post-metadata">

**Author:** ![Transistor](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/transistor/32/3380_2.png) [@Transistor](https://forum.inductiveautomation.com/u/Transistor)\
**Post date:** [July 19, 2025, 12:09am UTC](https://forum.inductiveautomation.com/t/displaying-forecasted-data-value-on-time-series-chart/108685/2 "2025-07-19T00:09:22Z")

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And what's the problem? Does it not work? What on the chart is incorrect?