feat: add point-based time-series forecasting support and optimize bitshuffle, delta, and lorenzo decoders.

Author: philipredstone

Makefile

@@ -45,7 +45,8 @@ deps: node_modules/.stamp
 
 # testdata is regenerated whenever cmd/gen-testdata changes.
 TESTDATA_FILES := format/testdata/minimal.wmt format/testdata/extended.wmt \
-                  format/testdata/compacted.wmt format/testdata/crc_corrupted.wmt
+                  format/testdata/compacted.wmt format/testdata/crc_corrupted.wmt \
+                  format/testdata/multistep.wmt
 
 $(TESTDATA_FILES): cmd/gen-testdata/main.go
 	mkdir -p format/testdata

cmd/gen-testdata/main.go

@@ -35,6 +35,57 @@ func main() {
 	crcPath := filepath.Join(outDir, "crc_corrupted.wmt")
 	makeCRCCorrupted(extendedPath, crcPath)
 	fmt.Printf("wrote %s\n", crcPath)
+
+	multistepPath := filepath.Join(outDir, "multistep.wmt")
+	makeMultistep(multistepPath, pixSize, refTime, fixedNow)
+	fmt.Printf("wrote %s\n", multistepPath)
+}
+
+// 4 hourly steps × 2 variables. Pixel values encode (timeStep, variable) so a
+// reader can verify both slicing and per-variable routing.
+func makeMultistep(path string, pixSize int, refTime time.Time, now time.Time) {
+	const steps = 4
+	const hourMs = int64(3600 * 1000)
+	vars := []struct {
+		Name   string
+		Offset float32
+	}{
+		{"temp", 100},
+		{"wind", 200},
+	}
+
+	tiles := make([]encoder.Tile, 0, steps*len(vars))
+	for _, v := range vars {
+		for t := uint32(0); t < steps; t++ {
+			px := make([]float32, pixSize*pixSize)
+			for i := range px {
+				px[i] = v.Offset + float32(t)
+			}
+			tiles = append(tiles, encoder.Tile{
+				Variable: v.Name, TimeStep: t, Z: 0, X: 0, Y: 0, Pixels: px,
+			})
+		}
+	}
+
+	specs := make([]encoder.VariableSpec, 0, len(vars))
+	for _, v := range vars {
+		specs = append(specs, encoder.VariableSpec{Name: v.Name, Unit: "u"})
+	}
+	opts := encoder.Options{
+		TilePixelSizeLog2:     7,
+		MinZoom:               0,
+		MaxZoom:               0,
+		ReferenceForecastTime: refTime,
+		TimeCatalog: format.TimeCatalog{
+			Regular: true, StartMs: refTime.UnixMilli(), IntervalMs: hourMs, Count: steps,
+		},
+		BBox:         [4]float64{-180, -85, 180, 85},
+		Variables:    specs,
+		CreationTime: now,
+	}
+	if err := encoder.Encode(tiles, opts, path); err != nil {
+		die(err)
+	}
 }
 
 func makeMinimal(path string, pixSize int, refTime time.Time, now time.Time) {

cmd/wmtiles/web/index.html

@@ -27,7 +27,7 @@
 <div id="top">
   <label>parameter <select id="param" disabled><option>loading…</option></select></label>
   <label>height <select id="height" disabled><option>n/a</option></select></label>
-  <label>time <input id="time" type="range" min="0" max="0" value="0" step="1" disabled> <span id="timeLabel"></span></label>
+  <label>time <input id="time" type="range" min="0" max="0" value="0" step="any" disabled> <span id="timeLabel"></span></label>
   <label>vmin <input id="vmin" type="number" step="any" style="width:90px" disabled></label>
   <label>vmax <input id="vmax" type="number" step="any" style="width:90px" disabled></label>
   <span id="status">opening…</span>