Trac #30774: use iterators inside call of .join for strings

as this avoids to create an intermediate list

URL: https://trac.sagemath.org/30774
Reported by: chapoton
Ticket author(s): Frédéric Chapoton
Reviewer(s): Samuel Lelièvre

Author: Release Manager

src/sage/algebras/letterplace/free_algebra_letterplace.pyx

@@ -596,11 +596,7 @@ cdef class FreeAlgebra_letterplace(Algebra):
                 raise NotImplementedError("\n  Apparently you tried to view the letterplace algebra with\n  shift-multiplication as the free algebra over a finitely\n  generated free abelian monoid.\n  In principle, this is correct, but it is not implemented, yet.")
 
             out.append(self._names[var_ind])
-            i += (self._degrees[var_ind]-1)
-            ### This was the original implementation, with "monoid hack" but without generator degrees
-            #s = '.'.join([('%s^%d'%(x,e) if e>1 else x) for x,e in zip(self._names,E[i*ngens:(i+1)*ngens]) if e])
-            #if s:
-            #    out.append(s)
+            i += self._degrees[var_ind] - 1
         return '*'.join(out)
 
     # Auxiliar methods

src/sage/calculus/calculus.py

@@ -1990,7 +1990,7 @@ def _laplace_latex_(self, *args):
         \mathcal{L}\left(f\left(t\right), t, s\right)
 
     """
-    return "\\mathcal{L}\\left(%s\\right)"%(', '.join([latex(x) for x in args]))
+    return "\\mathcal{L}\\left(%s\\right)" % (', '.join(latex(x) for x in args))
 
 def _inverse_laplace_latex_(self, *args):
     r"""
@@ -2008,7 +2008,8 @@ def _inverse_laplace_latex_(self, *args):
         sage: latex(inverse_laplace(F,s,t))
         \mathcal{L}^{-1}\left(F\left(s\right), s, t\right)
     """
-    return "\\mathcal{L}^{-1}\\left(%s\\right)"%(', '.join([latex(x) for x in args]))
+    return "\\mathcal{L}^{-1}\\left(%s\\right)" % (', '.join(latex(x) for x in args))
+
 
 # Return un-evaluated expression as instances of SFunction class
 _laplace = function_factory('laplace', print_latex_func=_laplace_latex_)

src/sage/combinat/abstract_tree.py

@@ -1408,7 +1408,7 @@ def to_hexacode(self):
             raise ValueError("the width of the tree is too large")
         if self.node_number() == 1:
             return "0"
-        return "".join(["%x" % len(self)] + [u.to_hexacode() for u in self])
+        return ("%x" % len(self)) + "".join(u.to_hexacode() for u in self)
 
     def tree_factorial(self):
         r"""

src/sage/crypto/block_cipher/miniaes.py

@@ -1655,13 +1655,14 @@ def GF_to_binary(self, G):
         elif isinstance(G, list):
             if len(G) == 0:
                 raise ValueError("input G must be an element of GF(16), a list of elements of GF(16), or a matrix over GF(16)")
-            S = "".join([str(self._GF_to_bin[g]) for g in G])
+            S = "".join(str(self._GF_to_bin[g]) for g in G)
             return B(S)
         # G is a matrix over GF(16)
         elif isinstance(G, Matrix_dense):
             if not (G.base_ring() is K):
                 raise TypeError("input G must be an element of GF(16), a list of elements of GF(16), or a matrix over GF(16)")
-            S = "".join([str(self._GF_to_bin[G[i][j]]) for i in range(G.nrows()) for j in range(G.ncols())])
+            S = "".join(str(self._GF_to_bin[G[i][j]])
+                        for i in range(G.nrows()) for j in range(G.ncols()))
             return B(S)
         # the type of G doesn't match the supported types
         else:
@@ -2057,7 +2058,7 @@ def integer_to_binary(self, N):
             bin = BinaryStrings()
             # Here, we assume that each element of the list is an integer n
             # such that 0 <= n <= 15. An error will be raised if otherwise.
-            b = "".join([str(self._int_to_bin[n]) for n in N])
+            b = "".join(str(self._int_to_bin[n]) for n in N)
             return bin(b)
         elif isinstance(N, Integer):
             # Here, we assume that N is an integer such that 0 <= n <= 15.

src/sage/doctest/control.py

@@ -862,7 +862,7 @@ def sort_sources(self):
             ....:     DC.stats[source.basename] = {'walltime': 0.1*(i+1)}
             sage: DC.sort_sources()
             Sorting sources by runtime so that slower doctests are run first....
-            sage: print("\n".join([source.basename for source in DC.sources]))
+            sage: print("\n".join(source.basename for source in DC.sources))
             sage.doctest.util
             sage.doctest.test
             sage.doctest.sources

src/sage/doctest/sources.py

@@ -823,17 +823,17 @@ def _test_enough_doctests(self, check_extras=True, verbose=True):
             else:
                 print("There are %s tests in %s that are shifted by %s" % (len(shortfall), self.path, dif))
                 if verbose:
-                    print("    The correct line numbers are %s" % (", ".join([str(n) for n in shortfall])))
+                    print("    The correct line numbers are %s" % (", ".join(str(n) for n in shortfall)))
                 return
         elif len(actual) < len(expected):
             print("There are %s tests in %s that are not being run" % (len(expected) - len(actual), self.path))
         elif check_extras:
             print("There are %s unexpected tests being run in %s" % (len(actual) - len(expected), self.path))
         if verbose:
             if shortfall:
-                print("    Tests on lines %s are not run" % (", ".join([str(n) for n in shortfall])))
+                print("    Tests on lines %s are not run" % (", ".join(str(n) for n in shortfall)))
             if check_extras and extras:
-                print("    Tests on lines %s seem extraneous" % (", ".join([str(n) for n in extras])))
+                print("    Tests on lines %s seem extraneous" % (", ".join(str(n) for n in extras)))
 
 
 class SourceLanguage:

src/sage/geometry/point_collection.pyx

@@ -563,8 +563,8 @@ cdef class PointCollection(SageObject):
                     for i, coordinate in enumerate(point):
                         widths[i] = max(widths[i], len(coordinate))
                 format += ",".join("{{:>{}}}".format(width) for width in widths)
-                r = ",\n".join([format.format(head, *point)
-                                for head, point in zip(heads, r)])
+                r = ",\n".join(format.format(head, *point)
+                               for head, point in zip(heads, r))
         elif _output_format == "tuple":
             r = tuple(self)
         elif _output_format == "matrix":

src/sage/graphs/generic_graph.py

@@ -1736,7 +1736,7 @@ def to_dictionary(self, edge_labels=False, multiple_edges=False):
              9: {4: [None], 6: [None], 7: [None]}}
         """
 
-        # Returning the resuls as a dictionary of lists
+        # Returning the results as a dictionary of lists
         #
         # dictionary :
         # {vertex : [list of (out-)neighbors]}

src/sage/groups/perm_gps/permgroup_element.pyx

@@ -934,7 +934,7 @@ cdef class PermutationGroupElement(MultiplicativeGroupElement):
 
     def _latex_(self):
         r"""
-        Returns a latex representation of this permutation.
+        Return a latex representation of this permutation.
 
         EXAMPLES::
 
@@ -947,7 +947,8 @@ cdef class PermutationGroupElement(MultiplicativeGroupElement):
             \left[(\text{\texttt{a}},\text{\texttt{b}})\right]
         """
         from sage.misc.latex import latex
-        return "".join(["(" + ",".join([latex(x) for x in cycle])+")" for cycle in self.cycle_tuples()])
+        return "".join(("(" + ",".join(latex(x) for x in cycle) + ")")
+                       for cycle in self.cycle_tuples())
 
     def __getitem__(self, i):
         """
@@ -956,10 +957,8 @@ cdef class PermutationGroupElement(MultiplicativeGroupElement):
 
         INPUT:
 
-
         -  ``i`` - integer
 
-
         OUTPUT: a permutation group element
 
         EXAMPLES::

src/sage/matroids/matroids_plot_helpers.py

@@ -780,10 +780,10 @@ def geomrep(M1, B1=None, lineorders1=None, pd=None, sp=False):
     if M.rank() == 0:
         limits = None
         loops = L
-        looptext = ", ".join([str(l) for l in loops])
+        looptext = ", ".join(str(l) for l in loops)
         rectx = -1
         recty = -1
-        rectw = 0.5 + 0.4*len(loops) + 0.5  # controlled based on len(loops)
+        rectw = 0.5 + 0.4 * len(loops) + 0.5  # controlled based on len(loops)
         recth = 0.6
         G += polygon2d([[rectx, recty], [rectx, recty+recth],
                         [rectx+rectw, recty+recth], [rectx+rectw, recty]],