Merge pull request #19781 from mwtoews/foreach-item

MAINT: refactor "for ... in range(len(" statements

8 files changed, 72 insertions, 75 deletions

diff --git a/numpy/core/records.py b/numpy/core/records.py
index b3474ad01..2c20b7d45 100644
--- a/numpy/core/records.py
+++ b/numpy/core/records.py
@@ -664,17 +664,17 @@ def fromarrays(arrayList, dtype=None, shape=None, formats=None,
     if nn > 0:
         shape = shape[:-nn]
 
+    _array = recarray(shape, descr)
+
+    # populate the record array (makes a copy)
     for k, obj in enumerate(arrayList):
         nn = descr[k].ndim
         testshape = obj.shape[:obj.ndim - nn]
+        name = _names[k]
         if testshape != shape:
-            raise ValueError("array-shape mismatch in array %d" % k)
+            raise ValueError(f'array-shape mismatch in array {k} ("{name}")')
 
-    _array = recarray(shape, descr)
-
-    # populate the record array (makes a copy)
-    for i in range(len(arrayList)):
-        _array[_names[i]] = arrayList[i]
+        _array[name] = obj
 
     return _array
 
diff --git a/numpy/core/tests/test_umath_complex.py b/numpy/core/tests/test_umath_complex.py
index ad09830d4..af5bbe59e 100644
--- a/numpy/core/tests/test_umath_complex.py
+++ b/numpy/core/tests/test_umath_complex.py
@@ -134,8 +134,7 @@ class TestClog:
         x = np.array([1+0j, 1+2j])
         y_r = np.log(np.abs(x)) + 1j * np.angle(x)
         y = np.log(x)
-        for i in range(len(x)):
-            assert_almost_equal(y[i], y_r[i])
+        assert_almost_equal(y, y_r)
 
     @platform_skip
     @pytest.mark.skipif(platform.machine() == "armv5tel", reason="See gh-413.")
@@ -365,8 +364,7 @@ class TestCpow:
         x = np.array([1+1j, 0+2j, 1+2j, np.inf, np.nan])
         y_r = x ** 2
         y = np.power(x, 2)
-        for i in range(len(x)):
-            assert_almost_equal(y[i], y_r[i])
+        assert_almost_equal(y, y_r)
 
     def test_scalar(self):
         x = np.array([1, 1j,         2,  2.5+.37j, np.inf, np.nan])
@@ -419,8 +417,7 @@ class TestCabs:
         x = np.array([1+1j, 0+2j, 1+2j, np.inf, np.nan])
         y_r = np.array([np.sqrt(2.), 2, np.sqrt(5), np.inf, np.nan])
         y = np.abs(x)
-        for i in range(len(x)):
-            assert_almost_equal(y[i], y_r[i])
+        assert_almost_equal(y, y_r)
 
     def test_fabs(self):
         # Test that np.abs(x +- 0j) == np.abs(x) (as mandated by C99 for cabs)
@@ -466,9 +463,10 @@ class TestCabs:
             return np.abs(complex(a, b))
 
         xa = np.array(x, dtype=complex)
-        for i in range(len(xa)):
-            ref = g(x[i], y[i])
-            check_real_value(f, x[i], y[i], ref)
+        assert len(xa) == len(x) == len(y)
+        for xi, yi in zip(x, y):
+            ref = g(xi, yi)
+            check_real_value(f, xi, yi, ref)
 
 class TestCarg:
     def test_simple(self):
diff --git a/numpy/f2py/f2py2e.py b/numpy/f2py/f2py2e.py
index a14f068f1..f2093d76c 100755
--- a/numpy/f2py/f2py2e.py
+++ b/numpy/f2py/f2py2e.py
@@ -359,33 +359,34 @@ def buildmodules(lst):
     cfuncs.buildcfuncs()
     outmess('Building modules...\n')
     modules, mnames, isusedby = [], [], {}
-    for i in range(len(lst)):
-        if '__user__' in lst[i]['name']:
-            cb_rules.buildcallbacks(lst[i])
+    for item in lst:
+        if '__user__' in item['name']:
+            cb_rules.buildcallbacks(item)
         else:
-            if 'use' in lst[i]:
-                for u in lst[i]['use'].keys():
+            if 'use' in item:
+                for u in item['use'].keys():
                     if u not in isusedby:
                         isusedby[u] = []
-                    isusedby[u].append(lst[i]['name'])
-            modules.append(lst[i])
-            mnames.append(lst[i]['name'])
+                    isusedby[u].append(item['name'])
+            modules.append(item)
+            mnames.append(item['name'])
     ret = {}
-    for i in range(len(mnames)):
-        if mnames[i] in isusedby:
+    for module, name in zip(modules, mnames):
+        if name in isusedby:
             outmess('\tSkipping module "%s" which is used by %s.\n' % (
-                mnames[i], ','.join(['"%s"' % s for s in isusedby[mnames[i]]])))
+                name, ','.join('"%s"' % s for s in isusedby[name])))
         else:
             um = []
-            if 'use' in modules[i]:
-                for u in modules[i]['use'].keys():
+            if 'use' in module:
+                for u in module['use'].keys():
                     if u in isusedby and u in mnames:
                         um.append(modules[mnames.index(u)])
                     else:
                         outmess(
-                            '\tModule "%s" uses nonexisting "%s" which will be ignored.\n' % (mnames[i], u))
-            ret[mnames[i]] = {}
-            dict_append(ret[mnames[i]], rules.buildmodule(modules[i], um))
+                            f'\tModule "{name}" uses nonexisting "{u}" '
+                            'which will be ignored.\n')
+            ret[name] = {}
+            dict_append(ret[name], rules.buildmodule(module, um))
     return ret
 
 
@@ -429,18 +430,20 @@ def run_main(comline_list):
     capi_maps.load_f2cmap_file(options['f2cmap_file'])
     postlist = callcrackfortran(files, options)
     isusedby = {}
-    for i in range(len(postlist)):
-        if 'use' in postlist[i]:
-            for u in postlist[i]['use'].keys():
+    for plist in postlist:
+        if 'use' in plist:
+            for u in plist['use'].keys():
                 if u not in isusedby:
                     isusedby[u] = []
-                isusedby[u].append(postlist[i]['name'])
-    for i in range(len(postlist)):
-        if postlist[i]['block'] == 'python module' and '__user__' in postlist[i]['name']:
-            if postlist[i]['name'] in isusedby:
+                isusedby[u].append(plist['name'])
+    for plist in postlist:
+        if plist['block'] == 'python module' and '__user__' in plist['name']:
+            if plist['name'] in isusedby:
                 # if not quiet:
-                outmess('Skipping Makefile build for module "%s" which is used by %s\n' % (
-                    postlist[i]['name'], ','.join(['"%s"' % s for s in isusedby[postlist[i]['name']]])))
+                outmess(
+                    f'Skipping Makefile build for module "{plist["name"]}" '
+                    'which is used by {}\n'.format(
+                        ','.join(f'"{s}"' for s in isusedby[plist['name']])))
     if 'signsfile' in options:
         if options['verbose'] > 1:
             outmess(
@@ -448,8 +451,8 @@ def run_main(comline_list):
             outmess('%s %s\n' %
                     (os.path.basename(sys.argv[0]), options['signsfile']))
         return
-    for i in range(len(postlist)):
-        if postlist[i]['block'] != 'python module':
+    for plist in postlist:
+        if plist['block'] != 'python module':
             if 'python module' not in options:
                 errmess(
                     'Tip: If your original code is Fortran source then you must use -m option.\n')
diff --git a/numpy/lib/index_tricks.py b/numpy/lib/index_tricks.py
index 8d1b6e5be..2a4402c89 100644
--- a/numpy/lib/index_tricks.py
+++ b/numpy/lib/index_tricks.py
@@ -149,9 +149,9 @@ class nd_grid:
         try:
             size = []
             typ = int
-            for k in range(len(key)):
-                step = key[k].step
-                start = key[k].start
+            for kk in key:
+                step = kk.step
+                start = kk.start
                 if start is None:
                     start = 0
                 if step is None:
@@ -161,19 +161,19 @@ class nd_grid:
                     typ = float
                 else:
                     size.append(
-                        int(math.ceil((key[k].stop - start)/(step*1.0))))
+                        int(math.ceil((kk.stop - start) / (step * 1.0))))
                 if (isinstance(step, (_nx.floating, float)) or
                         isinstance(start, (_nx.floating, float)) or
-                        isinstance(key[k].stop, (_nx.floating, float))):
+                        isinstance(kk.stop, (_nx.floating, float))):
                     typ = float
             if self.sparse:
                 nn = [_nx.arange(_x, dtype=_t)
                       for _x, _t in zip(size, (typ,)*len(size))]
             else:
                 nn = _nx.indices(size, typ)
-            for k in range(len(size)):
-                step = key[k].step
-                start = key[k].start
+            for k, kk in enumerate(key):
+                step = kk.step
+                start = kk.start
                 if start is None:
                     start = 0
                 if step is None:
@@ -181,7 +181,7 @@ class nd_grid:
                 if isinstance(step, (_nx.complexfloating, complex)):
                     step = int(abs(step))
                     if step != 1:
-                        step = (key[k].stop - start)/float(step-1)
+                        step = (kk.stop - start) / float(step - 1)
                 nn[k] = (nn[k]*step+start)
             if self.sparse:
                 slobj = [_nx.newaxis]*len(size)
diff --git a/numpy/lib/polynomial.py b/numpy/lib/polynomial.py
index 23021cafa..c40e50a57 100644
--- a/numpy/lib/polynomial.py
+++ b/numpy/lib/polynomial.py
@@ -152,9 +152,8 @@ def poly(seq_of_zeros):
         return 1.0
     dt = seq_of_zeros.dtype
     a = ones((1,), dtype=dt)
-    for k in range(len(seq_of_zeros)):
-        a = NX.convolve(a, array([1, -seq_of_zeros[k]], dtype=dt),
-                        mode='full')
+    for zero in seq_of_zeros:
+        a = NX.convolve(a, array([1, -zero], dtype=dt), mode='full')
 
     if issubclass(a.dtype.type, NX.complexfloating):
         # if complex roots are all complex conjugates, the roots are real.
@@ -770,8 +769,8 @@ def polyval(p, x):
     else:
         x = NX.asanyarray(x)
         y = NX.zeros_like(x)
-    for i in range(len(p)):
-        y = y * x + p[i]
+    for pv in p:
+        y = y * x + pv
     return y
 
 
@@ -1273,14 +1272,14 @@ class poly1d:
                 s = s[:-5]
             return s
 
-        for k in range(len(coeffs)):
-            if not iscomplex(coeffs[k]):
-                coefstr = fmt_float(real(coeffs[k]))
-            elif real(coeffs[k]) == 0:
-                coefstr = '%sj' % fmt_float(imag(coeffs[k]))
+        for k, coeff in enumerate(coeffs):
+            if not iscomplex(coeff):
+                coefstr = fmt_float(real(coeff))
+            elif real(coeff) == 0:
+                coefstr = '%sj' % fmt_float(imag(coeff))
             else:
-                coefstr = '(%s + %sj)' % (fmt_float(real(coeffs[k])),
-                                          fmt_float(imag(coeffs[k])))
+                coefstr = '(%s + %sj)' % (fmt_float(real(coeff)),
+                                          fmt_float(imag(coeff)))
 
             power = (N-k)
             if power == 0:
diff --git a/numpy/lib/tests/test_function_base.py b/numpy/lib/tests/test_function_base.py
index 1d694e92f..829691b1c 100644
--- a/numpy/lib/tests/test_function_base.py
+++ b/numpy/lib/tests/test_function_base.py
@@ -2772,11 +2772,6 @@ class TestInterp:
         assert_almost_equal(np.interp(x, xp, fp, period=360), y)
 
 
-def compare_results(res, desired):
-    for i in range(len(desired)):
-        assert_array_equal(res[i], desired[i])
-
-
 class TestPercentile:
 
     def test_basic(self):
diff --git a/numpy/lib/tests/test_shape_base.py b/numpy/lib/tests/test_shape_base.py
index fb7ba7874..a148e53da 100644
--- a/numpy/lib/tests/test_shape_base.py
+++ b/numpy/lib/tests/test_shape_base.py
@@ -392,7 +392,7 @@ class TestArraySplit:
         assert_(a.dtype.type is res[-1].dtype.type)
 
         # Same thing for manual splits:
-        res = array_split(a, [0, 1, 2], axis=0)
+        res = array_split(a, [0, 1], axis=0)
         tgt = [np.zeros((0, 10)), np.array([np.arange(10)]),
                np.array([np.arange(10)])]
         compare_results(res, tgt)
@@ -713,5 +713,9 @@ class TestMayShareMemory:
 
 # Utility
 def compare_results(res, desired):
-    for i in range(len(desired)):
-        assert_array_equal(res[i], desired[i])
+    """Compare lists of arrays."""
+    if len(res) != len(desired):
+        raise ValueError("Iterables have different lengths")
+    # See also PEP 618 for Python 3.10
+    for x, y in zip(res, desired):
+        assert_array_equal(x, y)
diff --git a/numpy/lib/utils.py b/numpy/lib/utils.py
index b1a916d4a..1f2cb66fa 100644
--- a/numpy/lib/utils.py
+++ b/numpy/lib/utils.py
@@ -351,8 +351,7 @@ def who(vardict=None):
     maxshape = 0
     maxbyte = 0
     totalbytes = 0
-    for k in range(len(sta)):
-        val = sta[k]
+    for val in sta:
         if maxname < len(val[0]):
             maxname = len(val[0])
         if maxshape < len(val[1]):
@@ -369,8 +368,7 @@ def who(vardict=None):
         prval = "Name %s Shape %s Bytes %s Type" % (sp1*' ', sp2*' ', sp3*' ')
         print(prval + "\n" + "="*(len(prval)+5) + "\n")
 
-    for k in range(len(sta)):
-        val = sta[k]
+    for val in sta:
         print("%s %s %s %s %s %s %s" % (val[0], ' '*(sp1-len(val[0])+4),
                                         val[1], ' '*(sp2-len(val[1])+5),
                                         val[2], ' '*(sp3-len(val[2])+5),