Heatmap: Left edge does not start at zero

[swharden]

Email from Feng Q.

It’s a bug？The coordinate system range was set, but the drawing exceeded the range of the coordinate system. You developed this control is very practical, very good, thank you very much！

[swharden]

Seems to be https://scottplot.net/cookbook/5.0/Heatmap/HeatmapInverted/ which I think is functioning as expected

[FengQingYangDad]

Thank you very much for your reply. Both X and Y coordinates are set in this coordinate system, the X coordinates are from 0 to 65, but the actual graph shows that the X-axis appears to start at -0.5. The same XY coordinate system has the phenomenon of outside the set range。

[swharden]

Thanks for the clarification @FengQingYangDad! I'll open this issue back up and we can take a closer look shortly and hopefully arrive at a good solution for the next release 👍

[FengQingYangDad]

thank you very much！

[swharden]

Default behavior is that the lower left cell is centered at (0, 0) resulting in the behavior you observe:

double[,] data = {
    { 1, 2, 3 },
    { 4, 5, 6 },
    { 7, 8, 9 },
};

myPlot.Add.Heatmap(data);

Set cell alignment to lower left for the bottom left corner of the heatmap to be at the origin:

double[,] data = {
    { 1, 2, 3 },
    { 4, 5, 6 },
    { 7, 8, 9 },
};

var hm = myPlot.Add.Heatmap(data);
hm.CellAlignment = Alignment.LowerLeft;

I'll add a cookbook recipe to make this feature more discoverable 👍