Charts: Fixed y-Axis?

Setup, Configuration and Use Items & Sitemaps
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1

Hi!

Is it possible to set a fixed scale for the y-axis of a chart item? For example, this is my chart for the weather temperature:
https://i.imgur.com/maCC1fI.png

The y-axis scale is based on the existing values and displays min → max. I’d like to fix the y-axis / temperature to display a scale from -10 to 30 °C.

Is that possible in any way?

Thanks!

2

No. With the built in charting what you see is what you get. If you want more control you need to look elsewhere for your charting needs. I highly recommend the InfluxDB+Grafana approach.

3

But I think there is some “dirty” method.
I created 2 new items

Number Chart_limit_low      "Linia ograniczająca niska" (group_temperature)
Number Chart_limit_high      "Linia ograniczająca wysoka" (group_temperature)

Added them to rrd4j.persist & mapdb.persist file and also to the same group like my outside temperature.
In sitemap created

Setpoint item=Chart_limit_low label="Linia ograniczająca niska [%.0f °C]"
Setpoint item=Chart_limit_high label="Linia ograniczająca wysoka [%.0f °C]"

for limit low set 0 and limit high set 25 and my chart looks better. Because this values remain same all the time so the chart “scale” let’s say will looks same all the time. I know that this is some around method but like for me works fine :slight_smile:

PNG
PNG1334×750 135 KB

This is my first post here - sorry if it’s not perfect :slight_smile:
I’m beginner but I would like to share my experience also.

4

Hi! I’m looking to implement the same solution. I have an air pollution sensor installed and I would like to show the maximum allowable value in the chart.
Could you pls. show how you defined the value in the persists?

Thx.

BR
Fregon

5

For rrd4j.persist like that.

// persistence strategies have a name and a definition and are referred to in the "Items" section
Strategies {
	// for rrd charts, we need a cron strategy
	everyMinute : "0 * * * * ?"
	everyHour : "0 0 * * * ?"
	everyDay : "0 0 0 * * ?"
	default = everyChange
}

Items {
	//* : strategy = everyChange, restoreOnStartup
	
	Lights, group_temperature, Contacts, Chart_limit_low, Chart_limit_high, Home_away, Chart_limit_low_2, Chart_limit_high_2, Contacts : strategy = everyUpdate, restoreOnStartup



}