spread reviews before sibling check

anki/sched.py

@@ -18,6 +18,7 @@ from anki.hooks import runHook
 class Scheduler(object):
     name = "std"
     haveCustomStudy = True
+    _spreadRev = True
 
     def __init__(self, col):
         self.col = col
@@ -873,6 +874,25 @@ select id from cards where did in %s and queue = 2 and due <= ? limit ?)"""
         # interval capped?
         return min(interval, conf['maxIvl'])
 
+    def _fuzzedIvl(self, ivl):
+        min, max = self._fuzzIvlRange(ivl)
+        return random.randint(min, max)
+
+    def _fuzzIvlRange(self, ivl):
+        if ivl < 2:
+            return [1, 1]
+        elif ivl == 2:
+            return [2, 3]
+        elif ivl < 7:
+            fuzz = int(ivl*0.25)
+        elif ivl < 30:
+            fuzz = max(2, int(ivl*0.15))
+        else:
+            fuzz = max(4, int(ivl*0.05))
+        # fuzz at least a day
+        fuzz = max(fuzz, 1)
+        return [ivl-fuzz, ivl+fuzz]
+
     def _constrainedIvl(self, ivl, conf, prev):
         "Integer interval after interval factor and prev+1 constraints applied."
         new = ivl * conf.get('ivlFct', 1)
@@ -890,6 +910,8 @@ select id from cards where did in %s and queue = 2 and due <= ? limit ?)"""
 
     def _adjRevIvl(self, card, idealIvl):
         "Given IDEALIVL, return an IVL away from siblings."
+        if self._spreadRev:
+            idealIvl = self._fuzzedIvl(idealIvl)
         idealDue = self.today + idealIvl
         conf = self._revConf(card)
         # find sibling positions

tests/test_sched.py

@@ -5,6 +5,10 @@ from tests.shared import  getEmptyDeck
 from anki.utils import  intTime
 from anki.hooks import addHook
 
+def checkRevIvl(d, targetIvl):
+    min, max = d.sched._fuzzIvlRange(targetIvl)
+    return min <= targetIvl <= max
+
 def test_basics():
     d = getEmptyDeck()
     d.reset()
@@ -148,7 +152,7 @@ def test_learn():
     d.sched.answerCard(c, 3)
     assert c.type == 2
     assert c.queue == 2
-    assert c.ivl == 4
+    assert checkRevIvl(d, 4)
     # revlog should have been updated each time
     assert d.db.scalar("select count() from revlog where type = 0") == 5
     # now failed card handling
@@ -302,8 +306,8 @@ def test_reviews():
     d.sched.answerCard(c, 2)
     assert c.queue == 2
     # the new interval should be (100 + 8/4) * 1.2 = 122
-    assert c.ivl == 122
-    assert c.due == d.sched.today + 122
+    assert checkRevIvl(d, 122)
+    assert c.due == d.sched.today + c.ivl
     # factor should have been decremented
     assert c.factor == 2350
     # check counters
@@ -315,8 +319,8 @@ def test_reviews():
     c.flush()
     d.sched.answerCard(c, 3)
     # the new interval should be (100 + 8/2) * 2.5 = 260
-    assert c.ivl == 260
-    assert c.due == d.sched.today + 260
+    assert checkRevIvl(d, 260)
+    assert c.due == d.sched.today + c.ivl
     # factor should have been left alone
     assert c.factor == 2500
     # ease 4
@@ -325,8 +329,8 @@ def test_reviews():
     c.flush()
     d.sched.answerCard(c, 4)
     # the new interval should be (100 + 8) * 2.5 * 1.3 = 351
-    assert c.ivl == 351
-    assert c.due == d.sched.today + 351
+    assert checkRevIvl(d, 351)
+    assert c.due == d.sched.today + c.ivl
     # factor should have been increased
     assert c.factor == 2650
     # leech handling
@@ -767,6 +771,7 @@ def test_cram_resched():
 
 def test_adjIvl():
     d = getEmptyDeck()
+    d.sched._spreadRev = False
     # add two more templates and set second active
     m = d.models.current(); mm = d.models
     t = mm.newTemplate("Reverse")