fix(playground): read the characters of one drawing in the same task

playground/shapes.js

@@ -477,6 +477,21 @@
     };
   }
 
+  // Shapes that are a letter or a digit depending on the task: a vertical
+  // line (l, I, 1), a ring (O, o, 0) and a Z (Z, z, 2).
+  const TWINS = new Set(["l", "I", "1", "O", "o", "0", "Z", "z"]);
+  // Characters written together are read together: next to a digit that is
+  // clearly a digit, a twin is read as a digit too, and next to a clear
+  // letter as a letter. "12" drawn on the Letters task used to read l, 2.
+  function agree(groups, parts, opts) {
+    const clear = parts.filter((p) => p && p.label && !TWINS.has(p.label));
+    const digits = clear.some((p) => p.task === "symbols");
+    const letters = clear.some((p) => p.task === "chars");
+    if (digits === letters) return parts;
+    const task = digits ? "symbols" : "chars";
+    return parts.map((p, i) => (p && p.label && TWINS.has(p.label) && p.task !== task ? recogniseOne(groups[i], { ...opts, task }) : p));
+  }
+
   // strokes: arrays of {x, y}. opts.size: the drawing area's height in
   // pixels. opts.task: "chars" or "symbols". Returns one character, or, for
   // characters written side by side, { sequence: [one per character] }.
@@ -486,7 +501,7 @@
     const { groups, gap } = characters(clean, opts.size || 170);
     if (groups.length < 2 || opts.ranking) return recogniseOne(clean, opts);
     const whole = recogniseOne(clean, opts);
-    const parts = groups.map((g) => recogniseOne(g, opts));
+    const parts = agree(groups, groups.map((g) => recogniseOne(g, opts)), opts);
     const allRead = parts.every((p) => p && p.label);
     // A clear gap means separate characters. A narrow one (a sloppy H whose
     // bar misses a stem) is one character if it reads as one.

tests/test_playground_shapes.py

@@ -540,6 +540,39 @@ def test_two_letters_side_by_side(pair):
     assert read.count(pair) >= 7, read
 
 
+def test_the_reported_12_on_the_letters_task_reads_1_2():
+    # Reported: drawn on the Letters task, the 1 was read as the letter l.
+    got = recognise([{"strokes": _reported("12"), "task": "chars", "size": 215}])
+    assert [c["label"] for c in got[0]["sequence"]] == ["1", "2"]
+
+
+@pytest.mark.parametrize(
+    "first,second,task,want",
+    [
+        # A clear digit makes its neighbour a digit: O is 0 next to a 2.
+        ("2", "O", "chars", "20"),
+        # A clear letter makes a vertical line the letter l, even on numbers.
+        ("b", "l", "symbols", "bl"),
+    ],
+)
+def test_characters_written_together_are_read_together(first, second, task, want):
+    rng = random.Random(want + task)
+    line = {"l": [path((0.5, 0.02), (0.52, 0.98))]}
+    sketches = {**SKETCHES, **MULTI, **line}
+    cases = []
+    for _ in range(8):
+        a = draw(sketches[first], rng, height=90, left=40)
+        right = max(p["x"] for st in a for p in st) + 18
+        cases.append(
+            {
+                "strokes": a + draw(sketches[second], rng, height=90, left=right),
+                "task": task,
+            }
+        )
+    read = ["".join(c["label"] or "?" for c in g["sequence"]) for g in recognise(cases)]
+    assert read.count(want) >= 7, read
+
+
 def test_one_character_with_a_gap_between_its_strokes_stays_one():
     # An H whose bar stops short of both stems, and a = and a ÷.
     rng = random.Random(9)