Type hint IntegratorLearner (#372)

* Add type-hints to adaptive/learner/integrator_learner.py

* Add type-hints to adaptive/tests/algorithm_4.py

* Add type-hints to adaptive/learner/integrator_coeffs.py

Author: basnijholt

adaptive/learner/integrator_coeffs.py

@@ -1,4 +1,5 @@
 # Based on an adaptive quadrature algorithm by Pedro Gonnet
+from __future__ import annotations
 
 from collections import defaultdict
 from fractions import Fraction
@@ -8,7 +9,7 @@
 import scipy.linalg
 
 
-def legendre(n):
+def legendre(n: int) -> list[list[Fraction]]:
     """Return the first n Legendre polynomials.
 
     The polynomials have *standard* normalization, i.e.
@@ -29,7 +30,7 @@ def legendre(n):
     return result
 
 
-def newton(n):
+def newton(n: int) -> np.ndarray:
     """Compute the monomial coefficients of the Newton polynomial over the
     nodes of the n-point Clenshaw-Curtis quadrature rule.
     """
@@ -86,7 +87,7 @@ def newton(n):
     return cf
 
 
-def scalar_product(a, b):
+def scalar_product(a: list[Fraction], b: list[Fraction]) -> Fraction:
     """Compute the polynomial scalar product int_-1^1 dx a(x) b(x).
 
     The args must be sequences of polynomial coefficients.  This
@@ -107,7 +108,7 @@ def scalar_product(a, b):
     return 2 * sum(c[i] / (i + 1) for i in range(0, lc, 2))
 
 
-def calc_bdef(ns):
+def calc_bdef(ns: tuple[int, int, int, int]) -> list[np.ndarray]:
     """Calculate the decompositions of Newton polynomials (over the nodes
     of the n-point Clenshaw-Curtis quadrature rule) in terms of
     Legandre polynomials.
@@ -133,7 +134,7 @@ def calc_bdef(ns):
     return result
 
 
-def calc_V(x, n):
+def calc_V(x: np.ndarray, n: int) -> np.ndarray:
     V = [np.ones(x.shape), x.copy()]
     for i in range(2, n):
         V.append((2 * i - 1) / i * x * V[-1] - (i - 1) / i * V[-2])

adaptive/learner/integrator_learner.py

@@ -5,6 +5,7 @@
 from collections import defaultdict
 from math import sqrt
 from operator import attrgetter
+from typing import TYPE_CHECKING, Callable
 
 import cloudpickle
 import numpy as np
@@ -25,7 +26,7 @@
     with_pandas = False
 
 
-def _downdate(c, nans, depth):
+def _downdate(c: np.ndarray, nans: list[int], depth: int) -> np.ndarray:
     # This is algorithm 5 from the thesis of Pedro Gonnet.
     b = coeff.b_def[depth].copy()
     m = coeff.ns[depth] - 1
@@ -45,7 +46,7 @@ def _downdate(c, nans, depth):
     return c
 
 
-def _zero_nans(fx):
+def _zero_nans(fx: np.ndarray) -> list[int]:
     """Caution: this function modifies fx."""
     nans = []
     for i in range(len(fx)):
@@ -55,7 +56,7 @@ def _zero_nans(fx):
     return nans
 
 
-def _calc_coeffs(fx, depth):
+def _calc_coeffs(fx: np.ndarray, depth: int) -> np.ndarray:
     """Caution: this function modifies fx."""
     nans = _zero_nans(fx)
     c_new = coeff.V_inv[depth] @ fx
@@ -135,27 +136,32 @@ class _Interval:
         "removed",
     ]
 
-    def __init__(self, a, b, depth, rdepth):
-        self.children = []
-        self.data = {}
+    def __init__(self, a: int | float, b: int | float, depth: int, rdepth: int) -> None:
+        self.children: list[_Interval] = []
+        self.data: dict[float, float] = {}
         self.a = a
         self.b = b
         self.depth = depth
         self.rdepth = rdepth
-        self.done_leaves = set()
-        self.depth_complete = None
+        self.done_leaves: set[_Interval] = set()
+        self.depth_complete: int | None = None
         self.removed = False
+        if TYPE_CHECKING:
+            self.ndiv: int
+            self.parent: _Interval | None
+            self.err: float
+            self.c: np.ndarray
 
     @classmethod
-    def make_first(cls, a, b, depth=2):
+    def make_first(cls, a: int, b: int, depth: int = 2) -> _Interval:
         ival = _Interval(a, b, depth, rdepth=1)
         ival.ndiv = 0
         ival.parent = None
         ival.err = sys.float_info.max  # needed because inf/2 == inf
         return ival
 
     @property
-    def T(self):
+    def T(self) -> np.ndarray:
         """Get the correct shift matrix.
 
         Should only be called on children of a split interval.
@@ -166,24 +172,24 @@ def T(self):
         assert left != right
         return coeff.T_left if left else coeff.T_right
 
-    def refinement_complete(self, depth):
+    def refinement_complete(self, depth: int) -> bool:
         """The interval has all the y-values to calculate the intergral."""
         if len(self.data) < coeff.ns[depth]:
             return False
         return all(p in self.data for p in self.points(depth))
 
-    def points(self, depth=None):
+    def points(self, depth: int | None = None) -> np.ndarray:
         if depth is None:
             depth = self.depth
         a = self.a
         b = self.b
         return (a + b) / 2 + (b - a) * coeff.xi[depth] / 2
 
-    def refine(self):
+    def refine(self) -> _Interval:
         self.depth += 1
         return self
 
-    def split(self):
+    def split(self) -> list[_Interval]:
         points = self.points()
         m = points[len(points) // 2]
         ivals = [
@@ -198,10 +204,10 @@ def split(self):
 
         return ivals
 
-    def calc_igral(self):
+    def calc_igral(self) -> None:
         self.igral = (self.b - self.a) * self.c[0] / sqrt(2)
 
-    def update_heuristic_err(self, value):
+    def update_heuristic_err(self, value: float) -> None:
         """Sets the error of an interval using a heuristic (half the error of
         the parent) when the actual error cannot be calculated due to its
         parents not being finished yet. This error is propagated down to its
@@ -214,7 +220,7 @@ def update_heuristic_err(self, value):
                 continue
             child.update_heuristic_err(value / 2)
 
-    def calc_err(self, c_old):
+    def calc_err(self, c_old: np.ndarray) -> float:
         c_new = self.c
         c_diff = np.zeros(max(len(c_old), len(c_new)))
         c_diff[: len(c_old)] = c_old
@@ -226,9 +232,9 @@ def calc_err(self, c_old):
                 child.update_heuristic_err(self.err / 2)
         return c_diff
 
-    def calc_ndiv(self):
+    def calc_ndiv(self) -> None:
         div = self.parent.c00 and self.c00 / self.parent.c00 > 2
-        self.ndiv += div
+        self.ndiv += int(div)
 
         if self.ndiv > coeff.ndiv_max and 2 * self.ndiv > self.rdepth:
             raise DivergentIntegralError
@@ -237,15 +243,15 @@ def calc_ndiv(self):
             for child in self.children:
                 child.update_ndiv_recursively()
 
-    def update_ndiv_recursively(self):
+    def update_ndiv_recursively(self) -> None:
         self.ndiv += 1
         if self.ndiv > coeff.ndiv_max and 2 * self.ndiv > self.rdepth:
             raise DivergentIntegralError
 
         for child in self.children:
             child.update_ndiv_recursively()
 
-    def complete_process(self, depth):
+    def complete_process(self, depth: int) -> tuple[bool, bool] | tuple[bool, np.bool_]:
         """Calculate the integral contribution and error from this interval,
         and update the done leaves of all ancestor intervals."""
         assert self.depth_complete is None or self.depth_complete == depth - 1
@@ -322,7 +328,7 @@ def complete_process(self, depth):
 
         return force_split, remove
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         lst = [
             f"(a, b)=({self.a:.5f}, {self.b:.5f})",
             f"depth={self.depth}",
@@ -334,7 +340,7 @@ def __repr__(self):
 
 
 class IntegratorLearner(BaseLearner):
-    def __init__(self, function, bounds, tol):
+    def __init__(self, function: Callable, bounds: tuple[int, int], tol: float) -> None:
         """
         Parameters
         ----------
@@ -368,16 +374,18 @@ def __init__(self, function, bounds, tol):
         plot : hv.Scatter
             Plots all the points that are evaluated.
         """
-        self.function = function
+        self.function = function  # type: ignore
         self.bounds = bounds
         self.tol = tol
         self.max_ivals = 1000
-        self.priority_split = []
+        self.priority_split: list[_Interval] = []
         self.data = {}
         self.pending_points = set()
-        self._stack = []
-        self.x_mapping = defaultdict(lambda: SortedSet([], key=attrgetter("rdepth")))
-        self.ivals = set()
+        self._stack: list[float] = []
+        self.x_mapping: dict[float, SortedSet] = defaultdict(
+            lambda: SortedSet([], key=attrgetter("rdepth"))
+        )
+        self.ivals: set[_Interval] = set()
         ival = _Interval.make_first(*self.bounds)
         self.add_ival(ival)
         self.first_ival = ival
@@ -387,10 +395,10 @@ def new(self) -> IntegratorLearner:
         return IntegratorLearner(self.function, self.bounds, self.tol)
 
     @property
-    def approximating_intervals(self):
+    def approximating_intervals(self) -> set[_Interval]:
         return self.first_ival.done_leaves
 
-    def tell(self, point, value):
+    def tell(self, point: float, value: float) -> None:
         if point not in self.x_mapping:
             raise ValueError(f"Point {point} doesn't belong to any interval")
         self.data[point] = value
@@ -426,7 +434,7 @@ def tell(self, point, value):
     def tell_pending(self):
         pass
 
-    def propagate_removed(self, ival):
+    def propagate_removed(self, ival: _Interval) -> None:
         def _propagate_removed_down(ival):
             ival.removed = True
             self.ivals.discard(ival)
@@ -436,7 +444,7 @@ def _propagate_removed_down(ival):
 
         _propagate_removed_down(ival)
 
-    def add_ival(self, ival):
+    def add_ival(self, ival: _Interval) -> None:
         for x in ival.points():
             # Update the mappings
             self.x_mapping[x].add(ival)
@@ -447,15 +455,15 @@ def add_ival(self, ival):
                 self._stack.append(x)
         self.ivals.add(ival)
 
-    def ask(self, n, tell_pending=True):
+    def ask(self, n: int, tell_pending: bool = True) -> tuple[list[float], list[float]]:
         """Choose points for learners."""
         if not tell_pending:
             with restore(self):
                 return self._ask_and_tell_pending(n)
         else:
             return self._ask_and_tell_pending(n)
 
-    def _ask_and_tell_pending(self, n):
+    def _ask_and_tell_pending(self, n: int) -> tuple[list[float], list[float]]:
         points, loss_improvements = self.pop_from_stack(n)
         n_left = n - len(points)
         while n_left > 0:
@@ -471,7 +479,7 @@ def _ask_and_tell_pending(self, n):
 
         return points, loss_improvements
 
-    def pop_from_stack(self, n):
+    def pop_from_stack(self, n: int) -> tuple[list[float], list[float]]:
         points = self._stack[:n]
         self._stack = self._stack[n:]
         loss_improvements = [
@@ -482,7 +490,7 @@ def pop_from_stack(self, n):
     def remove_unfinished(self):
         pass
 
-    def _fill_stack(self):
+    def _fill_stack(self) -> list[float]:
         # XXX: to-do if all the ivals have err=inf, take the interval
         # with the lowest rdepth and no children.
         force_split = bool(self.priority_split)
@@ -518,16 +526,16 @@ def _fill_stack(self):
         return self._stack
 
     @property
-    def npoints(self):
+    def npoints(self) -> int:
         """Number of evaluated points."""
         return len(self.data)
 
     @property
-    def igral(self):
+    def igral(self) -> float:
         return sum(i.igral for i in self.approximating_intervals)
 
     @property
-    def err(self):
+    def err(self) -> float:
         if self.approximating_intervals:
             err = sum(i.err for i in self.approximating_intervals)
             if err > sys.float_info.max: