Wrong calculation of fuel economy if missing odometer on fuel records

[pecataToshev]

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Platform

• Docker Image
• Windows Standalone Executable

Description
When calculating the fuel economy, the data is incorrect if there are missing odometer records attached to it.

e.g. on dates 2024-12-01 and 2024-09-28

I think it'd be correct if it's using the following formulas:
Δ(km) = ${currentOdometerForTheRecord} - ${previousOdometerInFuel}
Fuel Economy(l/100km) = sum(ConsumptionExcludingPreviousRecordWithOdometer) / Δ(km)

So the result will become something like this:

To calculate it I created a simple JS algorithm:

const nil = "---";
let res = []
for (let i = 0; i < data.length - 1; i++) {
    let fuelEconomy = nil;
    let delta = nil;
    let consumption = data[i]["Consumption(l)"];
    if (data[i]["Odometer(km)"] !== nil) {
        for (let ii = i + 1; ii < data.length; ii++) {
            if (data[ii]["Odometer(km)"] !== nil) {
                delta = data[i]["Odometer(km)"] - data[ii]["Odometer(km)"];
                break;
            }
            consumption += data[ii]["Consumption(l)"];
        }
    }
    if (delta !== nil) {
        fuelEconomy = (100 * consumption) / delta;
    }
    res.push({
        ...data[i],
        "Δ(km)": delta,
        "Fuel Economy(l/100km)": fuelEconomy,
    })
}

[hargata]

yeah...we're not sure if this is something that really needs fixing. The context behind making the odometer field optional is because of #619 where a user might not fill out the odometer at the point of fueling up but they are expected to fill out the odometer field eventually.

Your use-case doesn't seem right. What is the use case for only recording the odometer every 10-20 fuel ups?

[pecataToshev]

I often find myself in situations where accurately tracking my fuel usage is a challenge. For example:

1. Traveling in areas with limited or no internet access: I just save my fuel recipes and add them later, but often forget to note down the odometer reading at the time of fueling.
2. Adding historical fuel data: If I'm adding past fueling records that I didn't initially record in the app, it's difficult to accurately track my fuel efficiency because I might not have the original odometer readings for each of them.

I don't see why missing a single odometer reading on a fuel record should mess up all of the data with making the "delta" equal the odometer reading and basically making the fuel efficiency close to zero.

In the end this is a manual process and people might forget to do a step or two out of it

[hargata]

That makes sense, let me look into this

[pecataToshev]

Thanks, mate! Appreciate it! Let me know if I can help further.

[hargata]

kk, put in a fix for this, can you pull down the :edge tag docker image and try it?

[pecataToshev]

Works fine in the fuel:

However I think it might be slightly wrong in the Dashboard -> Vehicle Maintenance Report. Not sure if related to th current fix though.

[hargata]

that should be fixed now

[hargata]

Fix released.