DateTimeTickUnits: The X-axis of `DateTime` mixture 24-hour and 12-hour notation.

ScottPlot Version: 4.1.58.0

Operating System: Windows10

Application Type: WinForms

Question: The X-axis of DateTime mixture 24-hour and 12-hour notation.

Zoom in on a graph displaying DateTime data on the X-axis with the mouse wheel or right-click.

In this case, the 24-hour and 12-hour displays show different times, depending on whether they zoom to the nearest second or include milliseconds.

It appears that 24-hour notation is used for zooms that display up to seconds, and 12-hour notation is used for zooms that also display milliseconds.

Is this as expected?

pattern	Actual output	comment
(A) Zooms that display up to seconds.	1985/09/23 23:59:59	As expected.
(B) Zooms that also display milliseconds.	1985/09/23 11:59:59.5	The time format expects 23:59:59.5.

• In case (A): https://github.com/ScottPlot/ScottPlot/blob/07ab190973cbf8697ff8bdc98b4e6475ce40ea03/src/ScottPlot4/ScottPlot/Ticks/DateTimeTickUnits/DateTimeTickUnitBase.cs#L34-L39

• In case (B): https://github.com/ScottPlot/ScottPlot/blob/07ab190973cbf8697ff8bdc98b4e6475ce40ea03/src/ScottPlot4/ScottPlot/Ticks/DateTimeTickUnits/SecondsAndLess/DateTimeTickDecisecond.cs#L25-L30

Maybe HH is correct in (B) instead of hh?

The reproduced code is as follows:

<div>

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

        ExecuteRecipe(formsPlot1.Plot);
    }

    private void ExecuteRecipe(Plot plt)
    {
        // original source: https://github.com/ScottPlot/ScottPlot/blob/07ab190973cbf8697ff8bdc98b4e6475ce40ea03/src/ScottPlot4/ScottPlot.Cookbook/Recipes/Axis.cs#L208-L222

        // create data sample data
        var myDates = new DateTime[1000]; // Change: 100 --> 1000
        for (var i = 0; i < myDates.Length; i++)
            myDates[i] = new DateTime(1985, 9, 24).AddMinutes(10 * i); // Change: .AddDays(7 * i) --> .AddMinutes(10 * i)

        // Convert DateTime[] to double[] before plotting
        var xs = myDates.Select(x => x.ToOADate()).ToArray();
        var ys = DataGen.RandomWalk(myDates.Length);
        plt.AddScatter(xs, ys);

        // Then tell the axis to display tick labels using a time format
        plt.XAxis.DateTimeFormat(true);
    }
}

</div>

[bclehmann]

I actually have a better option, we can check if the configured locale uses 24 hour time and swap out hh for HH. Otherwise we leave it as is. It’s a hack, but it’s not as breaking (or broken) a breaking change.

[MareMare]

Sorry for the late reply.

However here the user would still have to override 12 DateTimeUnit classes just to change some formatting rules, which seems excessive.

Yeah, you are right. I was a bit shallow in my thinking.

So I think for the timebeing I’m just going to create a PR that enforces 24-hour clock, and then at some point we might circle back on letting people write their times differently.

Thank you for creating the PR.