Trac #33563: fix some tests of emptiness

as suggested by
{{{
 pylint -d all -e C1801 src/sage
}}}

URL: https://trac.sagemath.org/33563
Reported by: chapoton
Ticket author(s): Frédéric Chapoton
Reviewer(s): David Coudert

Author: Release Manager

build/pkgs/configure/checksums.ini

@@ -1,4 +1,4 @@
 tarball=configure-VERSION.tar.gz
-sha1=b96c0334857e7afceccdb63b4e9ccb0c2560961f
-md5=e18f9c50c26c1c4e6c004137fd9db79d
-cksum=2456915872
+sha1=8d686c033d3c8f745d0a6727c851f1293b9215a0
+md5=0909bbf96d514f3624c49247f2e39ac8
+cksum=1726119293

build/pkgs/configure/package-version.txt

@@ -1 +1 @@
-d7a2f1f4880be729ef4d26ceaf3f1b8af941feb8
+d4f178fe1d70db93e9fe390905dc8f2ccc9b326c

src/sage/calculus/calculus.py

@@ -1991,9 +1991,8 @@ def at(ex, *args, **kwds):
     if len(args) == 1 and isinstance(args[0], list):
         for c in args[0]:
             kwds[str(c.lhs())] = c.rhs()
-    else:
-        if len(args):
-            raise TypeError("at can take at most one argument, which must be a list")
+    elif args:
+        raise TypeError("at can take at most one argument, which must be a list")
 
     return ex.subs(**kwds)
 
@@ -2283,7 +2282,7 @@ def symbolic_expression_from_maxima_string(x, equals_sub=False, maxima=maxima):
     function_syms = {k: v for k, v in symbol_table.get('maxima', {}).items()
                      if _is_function(v)}
 
-    if not len(x):
+    if not x:
         raise RuntimeError("invalid symbolic expression -- ''")
     maxima.set('_tmp_', x)
 

src/sage/combinat/abstract_tree.py

@@ -1731,7 +1731,7 @@ def odd_nodes_tree(self, nodes, edges, matrix):
                 for i in range(split):
                     tmp(self[i], edge, nodes, edges, matrix)
                 # # prepare the root line
-                if len(matrix):
+                if matrix:
                     nb_of_and = matrix[0].count(sep)
                     sizetmp = len(matrix[0])
                 else:
@@ -1754,9 +1754,9 @@ def odd_nodes_tree(self, nodes, edges, matrix):
             if self.is_empty():
                 empty_tree()
             elif len(self) == 0 or all(subtree.is_empty()
-                    for subtree in self):
+                                       for subtree in self):
                 one_node_tree(self)
-            elif len(self) % 2 == 0:
+            elif not len(self) % 2:
                 pair_nodes_tree(self, nodes, edges, matrix)
             else:
                 odd_nodes_tree(self, nodes, edges, matrix)
@@ -1789,8 +1789,8 @@ def make_edges(edges):
                 ("\n" +
                 path_begin +
                     "\n\t".join(make_edges(edges)) +
-                path_end if len(edges) else "")
-                if len(matrix) else "") +
+                path_end if edges else "")
+                if matrix else "") +
             end_env +
             "}")
 

src/sage/combinat/binary_tree.py

@@ -2716,15 +2716,15 @@ def twisting_number(self):
             return tn
 
         L = self.comb('left')
-        if len(L):
+        if L:
             tn[0] += 1
             for h in L:
                 tw = BinaryTree([None, h]).twisting_number()
                 tn[0] += tw[0]
                 tn[1] += tw[1]
 
         R = self.comb('right')
-        if len(R):
+        if R:
             tn[1] += 1
             for l in R:
                 tw = BinaryTree([l, None]).twisting_number()

src/sage/combinat/chas/wqsym.py

@@ -646,7 +646,7 @@ def coproduct_on_basis(self, x):
                 sage: M.coproduct( M([[1], [2]]) )
                 M[] # M[{1}, {2}] + M[{1}] # M[{1}] + M[{1}, {2}] # M[]
             """
-            if not len(x):
+            if not x:
                 return self.one().tensor(self.one())
             K = self.indices()
 
@@ -1212,7 +1212,7 @@ def coproduct_on_basis(self, x):
             # The coproduct on the Q basis satisfies the same formula
             # as on the M basis. This is easily derived from the
             # formula on the M basis.
-            if not len(x):
+            if not x:
                 return self.one().tensor(self.one())
             K = self.indices()
 
@@ -1723,7 +1723,7 @@ def coproduct_on_basis(self, x):
                 sage: AA(M(x).coproduct()) == x.coproduct()
                 True
             """
-            if not len(x):
+            if not x:
                 return self.one().tensor(self.one())
             K = self.indices()
 

src/sage/combinat/fqsym.py

@@ -639,7 +639,7 @@ def coproduct_on_basis(self, x):
                 F[] # F[3, 2, 1] + F[1] # F[2, 1] + F[2, 1] # F[1]
                 + F[3, 2, 1] # F[]
             """
-            if not len(x):
+            if not x:
                 return self.one().tensor(self.one())
             return sum(self(Word(x[:i]).standard_permutation()).tensor(
                 self(Word(x[i:]).standard_permutation()))

src/sage/geometry/polyhedron/backend_cdd.py

@@ -334,7 +334,7 @@ def parse_V_representation(intro, data):
                 else:
                     self.parent()._make_Vertex(self, coefficients)
                     has_vertex = True
-            if len(self._Vrepresentation) and not has_vertex:
+            if self._Vrepresentation and not has_vertex:
                 # when the Polyhedron consists only of lines/rays from the
                 # origin, cddlib does not output the single vertex at the
                 # origin so we have to add it here as the Polyhedron class

src/sage/geometry/polyhedron/base5.py

@@ -332,7 +332,7 @@ def _test_pyramid(self, tester=None, **options):
 
         def check_pyramid_certificate(P, cert):
             others = set(v for v in P.vertices() if not v == cert)
-            if len(others):
+            if others:
                 tester.assertTrue(any(set(f.ambient_Vrepresentation()) == others for f in P.facets()))
 
         if self.is_compact():

src/sage/interfaces/gap.py

@@ -664,14 +664,14 @@ def _eval_line(self, line, allow_use_file=True, wait_for_prompt=True, restart_if
             # them (on Python 3), currently just using the default encoding
             normal, error = bytes_to_str(normal), bytes_to_str(error)
 
-            if len(error):
+            if error:
                 if 'Error, Rebuild completion files!' in error:
                     error += "\nRunning gap_reset_workspace()..."
                     self.quit()
                     gap_reset_workspace()
                 error = error.replace('\r','')
                 raise RuntimeError("%s produced error output\n%s\n   executing %s"%(self, error,line))
-            if not len(normal):
+            if not normal:
                 return ''
 
             if isinstance(wait_for_prompt, str) and normal.ends_with(wait_for_prompt):
@@ -683,7 +683,7 @@ def _eval_line(self, line, allow_use_file=True, wait_for_prompt=True, restart_if
             else:
                 n = 0
             out = normal[:-n]
-            if len(out) and out[-1] == "\n":
+            if out and out[-1] == "\n":
                 out = out[:-1]
             return out