Home Assistant History Graph Y-Axis Labeling Bug

by SLV Team 49 views
Home Assistant History Graph Shows Wrong Doubled Y-Axis Labeling

Hey guys! Having some weird issues with the history graph in Home Assistant? Specifically, are you seeing doubled or incorrect y-axis labels? You're not alone! Let's dive into this issue and see what's going on.

The Issue: Doubled Y-Axis Labels

So, here's the deal: in some history graphs, the y-axis labels are showing up as the same value twice in a row. For instance, you might see "3" repeated, even though the actual data plotted on the graph goes below that value. It's like the graph is rounding things in a funky way, and it's definitely not giving us the accurate representation we need.

Why is this happening? Well, it seems like the rounding mechanism for the y-axis labels might be a bit off. When you have entities with values that go to several decimal places (like three in this case), the graph might be trying to round these values for display purposes. However, it could be rounding them incorrectly, leading to this doubled labeling issue. Instead of seeing something like 2.95, you end up with a repeated "3" on the y-axis. This can be super misleading when you're trying to analyze your data and get a clear picture of what's happening with your sensors.

What does this look like in practice? Imagine you're monitoring the minimum and maximum voltage of your battery cells using the sensor.victronpv_battery_cell_min_voltage and sensor.victronpv_battery_cell_max_voltage entities. You plot these on a history graph to see how they're behaving over time. But instead of a smooth, accurate scale on the y-axis, you see these doubled labels, making it hard to get a precise reading of the voltage levels. It's like trying to read a ruler where some of the markings are duplicated – not very helpful!

What can you do about it? As a user, there might not be a whole lot you can directly tweak to fix this. It seems to be an issue with how the history graph component itself handles the y-axis labeling. However, reporting the issue (which is what we're doing here!) helps the Home Assistant developers become aware of the problem and work on a solution in future updates. In the meantime, you might try adjusting the range of the graph or the number of decimal places displayed (if that's configurable) to see if it helps alleviate the issue, but no guarantees!

Steps to Reproduce

Want to see if you can recreate this issue yourself? Here's how:

  1. Set up entities with values up to 3 decimals: You'll need some sensors that report values with a few decimal places. Battery voltage sensors are a good example, but you could also use temperature sensors or any other sensor that provides precise readings.
  2. Plot them in a history graph: Add a history graph card to your Home Assistant dashboard and include the entities you set up in the previous step.
  3. Observe the y-axis labels: Check the y-axis labels on the graph. Do you see any instances where the same value is repeated, even though the data points on the graph suggest there should be more granular values?

If you follow these steps and encounter the doubled y-axis labeling issue, it's a good indication that you're experiencing the same bug. Make sure to document your findings and provide as much detail as possible when reporting the issue to the Home Assistant community.

Example YAML Configuration

Here's an example of the YAML configuration used to create the history graph in question:

type: vertical-stack
cards:
  - type: history-graph
    entities:
      - entity: sensor.victronpv_battery_cell_min_voltage
      - entity: sensor.victronpv_battery_cell_max_voltage
    hours_to_show: 10
    logarithmic_scale: false

This configuration sets up a simple history graph that displays the values of sensor.victronpv_battery_cell_min_voltage and sensor.victronpv_battery_cell_max_voltage over a period of 10 hours. The logarithmic_scale option is set to false, which means the y-axis will use a linear scale. If you're seeing the doubled y-axis labeling issue, this configuration can help you reproduce it and test any potential solutions.

Environment Details

  • Home Assistant Core Version: 2025.10.3
  • Browsers Affected: Firefox 144.0.2, Vivaldi 7.6.3797.63, Android App 2028.8.7-full

It's worth noting that this issue has been observed across multiple browsers, which suggests it's not a browser-specific problem. The fact that it also occurs in the Android app further reinforces this idea. This information can be helpful for the Home Assistant developers when they're investigating the bug and trying to identify the root cause.

Troubleshooting Steps Already Taken

Before reporting this issue, the following troubleshooting steps were performed:

  • Updated to the latest Home Assistant version: Ensures that the issue isn't already resolved in a newer release.
  • Cleared browser cache: Eliminates the possibility of cached data causing display problems.
  • Tried different browsers: Helps determine if the issue is browser-specific.
  • Reproduced in safe mode: Rules out conflicts with custom resources.

These steps are important because they help narrow down the possible causes of the issue and provide valuable information to the developers. By performing these checks, you can be more confident that you're reporting a genuine bug in Home Assistant itself.

Possible Causes and Workarounds

Okay, so we've established that there's a weird y-axis labeling issue in the history graph. But what could be causing it, and are there any temporary fixes we can try?

1. Rounding Errors: As mentioned earlier, the most likely culprit is the way Home Assistant is rounding the values for the y-axis labels. It might be using a simple rounding algorithm that doesn't account for the specific range of values being displayed, leading to the doubled labels. There isn't much you can do directly to change this, as it's an internal part of the history graph component.

2. Data Resolution: Another possibility is that the data being fed to the graph has a higher resolution than the graph can accurately display. For example, if your sensors are reporting values with six decimal places, but the graph only displays two, there might be some loss of precision that contributes to the labeling issue. You could try reducing the resolution of your sensor data (if possible) to see if it makes a difference. However, this might not be ideal if you need the higher precision for other purposes.

3. Graph Configuration: While it's unlikely to be the main cause, the way you've configured your history graph could be playing a role. For instance, if you're using a very narrow y-axis range, the rounding errors might be more pronounced. Try adjusting the min and max values for the y-axis (if that's configurable) to see if it helps. You could also experiment with different graph types or options to see if any of them avoid the issue.

4. Theme Issues: It's a long shot, but sometimes theme-related problems can cause unexpected display glitches. Try switching to a different Home Assistant theme to see if the y-axis labeling issue disappears. If it does, then you know the problem is related to your theme, and you can try tweaking its settings to fix it.

5. Wait for an Update: Ultimately, the best solution might be to simply wait for an update to Home Assistant that addresses the bug. The developers are usually pretty responsive to reported issues, so there's a good chance they'll fix it in a future release. In the meantime, you can use the workarounds above to try to mitigate the problem.

Conclusion

So, there you have it – a deep dive into the doubled y-axis labeling issue in Home Assistant's history graph. While it's definitely a frustrating bug, understanding the possible causes and workarounds can help you deal with it until a proper fix is released. And remember, reporting the issue to the Home Assistant community is always a good idea, as it helps the developers improve the platform for everyone. Keep an eye out for future updates, and happy graphing!