Trac #34847: modernize some for loops in cython files

changing things like
{{{
for i from 0 <= i < n
}}}
to
{{{
for i in range(n)
}}}

There remains many, as can be seen using
{{{
git grep " from .*<=" src/sage/
}}}

URL: https://trac.sagemath.org/34847
Reported by: chapoton
Ticket author(s): Frédéric Chapoton
Reviewer(s): David Coudert

src/sage/combinat/expnums.pyx

@@ -87,17 +87,17 @@ def expnums(int n, int aa):
     mpz_init_set_si(bell[1], aa)
     cdef int i
     cdef int k
-    for i from 1 <= i < n:
+    for i in range(1, n):
         mpz_init(bell[i+1])
         mpz_mul(bell[i+1], a, bell[1])
-        for k from 0 <= k < i:
+        for k in range(i):
             mpz_add(bell[i-k], bell[i-k], bell[i-k+1])
 
         z = Integer.__new__(Integer)
         mpz_set(z.value, bell[1])
         r.append(z)
 
-    for i from 1 <= i <= n:
+    for i in range(1, n + 1):
         mpz_clear(bell[i])
     sig_free(bell)
 

src/sage/libs/coxeter3/coxeter.pyx

@@ -980,7 +980,7 @@ cdef class CoxGroupElement:
 
         cdef Length i = 0
         cdef CoxGroupElement res
-        for i from 0 <= i < list.size():
+        for i in range(list.size()):
             res = self._new()
             res.word = list[i]
             coatoms.append(res)

src/sage/media/channels.pyx

@@ -17,12 +17,12 @@ def _separate_channels(_data, _width, _nchannels):
     if width == 1:
         # handle the one byte case
 
-        for n from 0 <= n < l:
+        for n in range(l):
             channel_data[n % nchannels].append(ord(data[n])-127)
 
     elif width == 2:
         a = 32768
-        for n from 0 <= n < l:
+        for n in range(l):
             # compute the value as an integer
             x = <int> (data[2*n]) + 256 * <int>(data[2*n + 1])
             #x -= 65536*(x > a)

src/sage/probability/probability_distribution.pyx

@@ -307,11 +307,10 @@ cdef class SphericalDistribution(ProbabilityDistribution):
             sage: T.get_random_element()  # rel tol 4e-16
             (0.07961564104639995, -0.05237671627581255, 0.9954486572862178)
         """
-
         cdef int i
         v = [0]*self.dimension
         gsl_ran_dir_nd(self.r, self.dimension, self.vec)
-        for i from 0 <= i<self.dimension:
+        for i in range(self.dimension):
             v[i] = self.vec[i]
         return vector(sage.rings.real_double.RDF, v) #This could be made more efficient by directly constructing the vector, TODO.
 

src/sage/quivers/algebra_elements.pxi

@@ -219,7 +219,7 @@ cdef int negdeglex(path_mon_t M1, path_mon_t M2) except -2:
         if M1.s_len < M2.s_len:
             return -1
         return 1
-    for index from 0 <= index < M1.path.length:
+    for index in range(M1.path.length):
         item1 = biseq_getitem(M1.path, index)
         item2 = biseq_getitem(M2.path, index)
         sig_check()
@@ -256,7 +256,7 @@ cdef int deglex(path_mon_t M1, path_mon_t M2) except -2:
         if M1.s_len < M2.s_len:
             return 1
         return -1
-    for index from 0 <= index < M1.path.length:
+    for index in range(M1.path.length):
         item1 = biseq_getitem(M1.path, index)
         item2 = biseq_getitem(M2.path, index)
         sig_check()

src/sage/schemes/elliptic_curves/descent_two_isogeny.pyx

@@ -2,15 +2,15 @@ r"""
 Descent on elliptic curves over `\QQ` with a 2-isogeny
 """
 
-#*****************************************************************************
+# ***************************************************************************
 #       Copyright (C) 2009 Robert L. Miller <rlmillster@gmail.com>
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
 # the Free Software Foundation, either version 2 of the License, or
 # (at your option) any later version.
-#                  http://www.gnu.org/licenses/
-#*****************************************************************************
+#                  https://www.gnu.org/licenses/
+# ***************************************************************************
 
 from cysignals.memory cimport sig_malloc, sig_free
 from cysignals.signals cimport sig_on, sig_off
@@ -316,7 +316,7 @@ cdef bint Zp_soluble_siksek(mpz_t a, mpz_t b, mpz_t c, mpz_t d, mpz_t e,
         result = 0
         (<nmod_poly_factor_struct *>f_factzn)[0].num = 0 # reset data struct
         qq = nmod_poly_factor(f_factzn, f)
-        for i from 0 <= i < f_factzn.num:
+        for i in range(f_factzn.num):
             if f_factzn.exp[i]&1:
                 result = 1
                 break
@@ -327,15 +327,15 @@ cdef bint Zp_soluble_siksek(mpz_t a, mpz_t b, mpz_t c, mpz_t d, mpz_t e,
 
         nmod_poly_zero(f)
         nmod_poly_set_coeff_ui(f, 0, 1)
-        for i from 0 <= i < f_factzn.num:
-            for j from 0 <= j < (f_factzn.exp[i]>>1):
+        for i in range(f_factzn.num):
+            for j in range(f_factzn.exp[i]>>1):
                 nmod_poly_mul(f, f, &f_factzn.p[i])
 
         (<nmod_poly_factor_struct *>f_factzn)[0].num = 0 # reset data struct
         nmod_poly_factor(f_factzn, f)
         has_roots = 0
         j = 0
-        for i from 0 <= i < f_factzn.num:
+        for i in range(f_factzn.num):
             if nmod_poly_degree(&f_factzn.p[i]) == 1 and 0 != nmod_poly_get_coeff_ui(&f_factzn.p[i], 1):
                 has_roots = 1
                 roots[j] = pp_ui - nmod_poly_get_coeff_ui(&f_factzn.p[i], 0)
@@ -393,7 +393,7 @@ cdef bint Zp_soluble_siksek(mpz_t a, mpz_t b, mpz_t c, mpz_t d, mpz_t e,
 
         result = 0
         mpz_init(tt)
-        for i from 0 <= i < j:
+        for i in range(j):
             mpz_mul_ui(tt, aaa, roots[i])
             mpz_add(tt, tt, bbb)
             mpz_mul_ui(tt, tt, roots[i])
@@ -454,7 +454,7 @@ cdef bint Zp_soluble_siksek(mpz_t a, mpz_t b, mpz_t c, mpz_t d, mpz_t e,
         has_roots = 0
         has_single_roots = 0
         j = 0
-        for i from 0 <= i < f_factzn.num:
+        for i in range(f_factzn.num):
             if nmod_poly_degree(&f_factzn.p[i]) == 1 and 0 != nmod_poly_get_coeff_ui(&f_factzn.p[i], 1):
                 has_roots = 1
                 if f_factzn.exp[i] == 1:
@@ -473,7 +473,7 @@ cdef bint Zp_soluble_siksek(mpz_t a, mpz_t b, mpz_t c, mpz_t d, mpz_t e,
             mpz_init(cc)
             mpz_init(dd)
             mpz_init(ee)
-        for i from 0 <= i < j:
+        for i in range(j):
             fmpz_poly_zero(f1)
             fmpz_poly_zero(linear)
             fmpz_poly_set_coeff_mpz(f1, 0, e)
@@ -558,7 +558,7 @@ cdef bint Zp_soluble_siksek_large_p(mpz_t a, mpz_t b, mpz_t c, mpz_t d, mpz_t e,
 
         f = ntl.ZZ_pX([1], P)
         for factor, exponent in f_factzn:
-            for j from 0 <= j < (exponent/2):
+            for j in range(exponent // 2):
                 f *= factor
 
         f /= f.leading_coefficient()
@@ -631,7 +631,7 @@ cdef bint Zp_soluble_siksek_large_p(mpz_t a, mpz_t b, mpz_t c, mpz_t d, mpz_t e,
 
         result = 0
         mpz_init(tt)
-        for i from 0 <= i < j:
+        for i in range(j):
             mpz_mul(tt, aaa, roots[i])
             mpz_add(tt, tt, bbb)
             mpz_mul(tt, tt, roots[i])
@@ -712,7 +712,7 @@ cdef bint Zp_soluble_siksek_large_p(mpz_t a, mpz_t b, mpz_t c, mpz_t d, mpz_t e,
             mpz_init(cc)
             mpz_init(dd)
             mpz_init(ee)
-        for i from 0 <= i < j:
+        for i in range(j):
             fmpz_poly_zero(f1)
             fmpz_poly_zero(linear)
             fmpz_poly_set_coeff_mpz(f1, 0, e)
@@ -958,7 +958,7 @@ cdef int count(mpz_t c_mpz, mpz_t d_mpz, mpz_t *p_list, unsigned long p_list_len
 
     # Set up coefficient array, and static variables
     cdef mpz_t *coeffs = <mpz_t *> sig_malloc(5 * sizeof(mpz_t))
-    for i from 0 <= i <= 4:
+    for i in range(5):
         mpz_init(coeffs[i])
     mpz_set_ui(coeffs[1], 0)     #
     mpz_set(coeffs[2], c_mpz)    # These never change
@@ -969,7 +969,7 @@ cdef int count(mpz_t c_mpz, mpz_t d_mpz, mpz_t *p_list, unsigned long p_list_len
     # local solubility over RR)
     cdef mpz_t *p_div_d_mpz = <mpz_t *> sig_malloc((p_list_len+1) * sizeof(mpz_t))
     n_primes = 0
-    for i from 0 <= i < p_list_len:
+    for i in range(p_list_len):
         if mpz_divisible_p(d_mpz, p_list[i]):
             mpz_init(p_div_d_mpz[n_primes])
             mpz_set(p_div_d_mpz[n_primes], p_list[i])
@@ -987,7 +987,7 @@ cdef int count(mpz_t c_mpz, mpz_t d_mpz, mpz_t *p_list, unsigned long p_list_len
     mpz_set_ui(n2, 0)
     while mpz_cmp(j, n_divisors) < 0:
         mpz_set_ui(coeffs[4], 1)
-        for i from 0 <= i < n_primes:
+        for i in range(n_primes):
             if mpz_tstbit(j, i):
                 mpz_mul(coeffs[4], coeffs[4], p_div_d_mpz[i])
         if verbosity > 3:
@@ -1012,7 +1012,7 @@ cdef int count(mpz_t c_mpz, mpz_t d_mpz, mpz_t *p_list, unsigned long p_list_len
         if not found_global_points:
             # Test whether the quartic is everywhere locally soluble:
             els = 1
-            for i from 0 <= i < p_list_len:
+            for i in range(p_list_len):
                 if not Qp_soluble(coeffs[4], coeffs[3], coeffs[2], coeffs[1], coeffs[0], p_list[i]):
                     els = 0
                     break
@@ -1035,11 +1035,11 @@ cdef int count(mpz_t c_mpz, mpz_t d_mpz, mpz_t *p_list, unsigned long p_list_len
                         print("\nDone calling ratpoints for large point search")
         mpz_add_ui(j, j, 1)
     mpz_clear(j)
-    for i from 0 <= i < n_primes:
+    for i in range(n_primes):
         mpz_clear(p_div_d_mpz[i])
     sig_free(p_div_d_mpz)
     mpz_clear(n_divisors)
-    for i from 0 <= i <= 4:
+    for i in range(5):
         mpz_clear(coeffs[i])
     sig_free(coeffs)
     return 0
@@ -1202,16 +1202,16 @@ def two_descent_by_two_isogeny_work(Integer c, Integer d,
         p_list_len = 1
         n_factor_init(&fact)
         n_factor(&fact, mpz_get_ui(d_mpz), proof)
-        for i from 0 <= i < fact.num:
+        for i in range(fact.num):
             p = fact.p[i]
             if p != 2:
                 mpz_init_set_ui(p_list_mpz[p_list_len], p)
                 p_list_len += 1
         n_factor(&fact, mpz_get_ui(d_prime_mpz), proof)
-        for i from 0 <= i < fact.num:
+        for i in range(fact.num):
             p = fact.p[i]
             found = 0
-            for j from 0 <= j < p_list_len:
+            for j in range(p_list_len):
                 if mpz_cmp_ui(p_list_mpz[j], p)==0:
                     found = 1
                     break
@@ -1233,7 +1233,7 @@ def two_descent_by_two_isogeny_work(Integer c, Integer d,
         if P not in primes: primes.append(P)
         p_list_len = len(primes)
         p_list_mpz = <mpz_t *> sig_malloc(p_list_len * sizeof(mpz_t))
-        for i from 0 <= i < p_list_len:
+        for i in range(p_list_len):
             P = Integer(primes[i])
             mpz_init_set(p_list_mpz[i], P.value)
     if d_neg:
@@ -1257,7 +1257,7 @@ def two_descent_by_two_isogeny_work(Integer c, Integer d,
           global_limit_small, global_limit_large, verbosity, selmer_only,
           n1_prime.value, n2_prime.value)
 
-    for i from 0 <= i < p_list_len:
+    for i in range(p_list_len):
         mpz_clear(p_list_mpz[i])
     sig_free(p_list_mpz)
 

src/sage/schemes/toric/divisor_class.pyx

@@ -329,7 +329,7 @@ def _ToricRationalDivisorClass_unpickle_v1(parent, entries,
     v._init(degree, parent)
     cdef Rational z
     cdef Py_ssize_t i
-    for i from 0 <= i < degree:
+    for i in range(degree):
         z = Rational(entries[i])
         mpq_set(v._entries[i], z.value)
     v._is_immutable = not is_mutable

src/sage/structure/list_clone.pyx

@@ -1278,7 +1278,7 @@ cdef class ClonableIntArray(ClonableElement):
         if self._list is not NULL:
             raise ValueError("resizing is forbidden")
         self._alloc_(len(lst))
-        for i from 0 <= i < self._len:
+        for i in range(self._len):
             self._list[i] = lst[i]
 
         self._is_immutable = immutable
@@ -1390,7 +1390,7 @@ cdef class ClonableIntArray(ClonableElement):
         cdef int i
         cdef list L = <list> PyList_New(self._len)
         cdef object o
-        for i from 0<=i<self._len:
+        for i in range(self._len):
             o = PyInt_FromLong(self._list[i])
             Py_INCREF(o)
             PyList_SET_ITEM(L, i, o)
@@ -1524,7 +1524,7 @@ cdef class ClonableIntArray(ClonableElement):
             False
         """
         cdef int i
-        for i from 0 <= i < self._len:
+        for i in range(self._len):
             if item == self._list[i]:
                 return True
         return False
@@ -1545,7 +1545,7 @@ cdef class ClonableIntArray(ClonableElement):
             ValueError: list.index(x): x not in list
         """
         cdef int i
-        for i from 0 <= i < self._len:
+        for i in range(self._len):
             if item == self._list[i]:
                 return i
         raise ValueError("list.index(x): x not in list")
@@ -1664,7 +1664,7 @@ cdef class ClonableIntArray(ClonableElement):
         res._parent = self._parent
         if self:
             res._alloc_(self._len)
-            for i from 0 <= i < res._len:
+            for i in range(self._len):
                 res._list[i] = self._list[i]
         if HAS_DICTIONARY(self):
             res.__dict__ = self.__dict__.copy()

src/sage/symbolic/expression.pyx

@@ -7000,7 +7000,7 @@ cdef class Expression(Expression_abc):
         # the following is a temporary fix for GiNaC bug #9505
         if is_a_mul(ss._gobj): # necessarily n=1 here
             res = self
-            for i from 0 <= i < ss._gobj.nops():
+            for i in range(ss._gobj.nops()):
                 res = res.coefficient(new_Expression_from_GEx(self._parent, ss._gobj.op(i)))
             return res
         sig_on()
@@ -10135,7 +10135,7 @@ cdef class Expression(Expression_abc):
                 sig_off()
             return new_Expression_from_GEx(self._parent, ex)
         elif is_a_mul(self._gobj):
-            for i from 0 <= i < self._gobj.nops():
+            for i in range(self._gobj.nops()):
                 oper = self._gobj.op(i)
                 if not is_a_power(oper):
                     vec.push_back(oper)
@@ -10225,7 +10225,7 @@ cdef class Expression(Expression_abc):
                 sig_off()
             return new_Expression_from_GEx(self._parent, ex)
         elif is_a_mul(self._gobj):
-            for i from 0 <= i < self._gobj.nops():
+            for i in range(self._gobj.nops()):
                 oper = self._gobj.op(i)
                 if is_a_power(oper):
                     ex = oper.op(0)
@@ -10318,7 +10318,7 @@ cdef class Expression(Expression_abc):
             return (new_Expression_from_GEx(self._parent, ex.op(0)),
                     new_Expression_from_GEx(self._parent, ex.op(1)))
         elif is_a_mul(self._gobj):
-            for i from 0 <= i < self._gobj.nops():
+            for i in range(self._gobj.nops()):
                 oper = self._gobj.op(i)
                 if is_a_power(oper):   # oper = ex^power
                     ex = oper.op(0)

src/sage/symbolic/pynac_function_impl.pxi

@@ -42,7 +42,7 @@ cpdef call_registered_function(unsigned serial,
     cdef GEx res
     cdef GExVector vec
     if nargs == 0 or nargs > 3:
-        for i from 0 <= i < len(args):
+        for i in range(len(args)):
             vec.push_back((<Expression>args[i])._gobj)
         res = g_function_evalv(serial, vec, hold)
     elif nargs == 1: