gh-36079: fix and activate pycodestyle E301 in pyx files

    
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This is fixing

E301 expected 1 blank line, found 0

in all pyx files and adding the check to the linter

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URL: #36079
Reported by: Frédéric Chapoton
Reviewer(s): David Coudert, Frédéric Chapoton

src/sage/graphs/edge_connectivity.pyx

@@ -1197,7 +1197,6 @@ cdef class GabowEdgeConnectivity:
         raise ValueError("the value of the edge connectivity has not been "
                          "properly computed. This may result from an interruption")
 
-
     #
     # Packing arborescences
     #

src/sage/libs/giac/giac.pyx

@@ -1266,11 +1266,10 @@ cdef class Pygen(GiacMethods_base):
         GIAC_archive( <string>encstring23(filename), (<Pygen>self).gptr[0], context_ptr)
         sig_off()
 
-
-
     # NB: with giac <= 1.2.3-57 redim doesn't have a non evaluated for so Pygen('redim') fails.
     # hence replacement  for redim:
-    def redim(self,a,b=None):
+
+    def redim(self, a, b=None):
         """
         Increase the size of a matrix when possible, otherwise return self.
 
@@ -1677,11 +1676,11 @@ cdef class Pygen(GiacMethods_base):
                 xyplot=[[(u.real())._double,(u.im())._double] for u in l]
 
 
-        if (xyscat != []):
-            result=scatter_plot(xyscat)
+        if xyscat:
+            result = scatter_plot(xyscat)
 
         else:
-            result=line(xyplot)
+            result = line(xyplot)
         sig_off()
 
         return result
@@ -1695,11 +1694,11 @@ cdef class Pygen(GiacMethods_base):
     #
     # # # # # # # # # # # # # # # # # # # # # # # # #
 
-    def __richcmp__( self, other,op):
+    def __richcmp__(self, other, op):
         if not isinstance(other, Pygen):
-            other=Pygen(other)
+            other = Pygen(other)
         if not isinstance(self, Pygen):
-            self=Pygen(self)
+            self = Pygen(self)
         sig_on()
         result= giacgenrichcmp((<Pygen>self).gptr[0],(<Pygen>other).gptr[0], op, context_ptr )
         sig_off()
@@ -1708,10 +1707,11 @@ cdef class Pygen(GiacMethods_base):
     #
     # Some attributes of the gen class:
     #
+
     property _type:
         def __get__(self):
             sig_on()
-            result=self.gptr.type
+            result = self.gptr.type
             sig_off()
             return result
 
@@ -1723,30 +1723,27 @@ cdef class Pygen(GiacMethods_base):
             sig_off()
             return result
 
-
-
     property _val:  # immediate int (type _INT_)
         """
         immediate int value of an _INT_ type gen.
         """
         def __get__(self):
-            if(self._type == 0):
+            if self._type == 0:
                 sig_on()
-                result=self.gptr.val
+                result = self.gptr.val
                 sig_off()
                 return result
             else:
                 raise TypeError("cannot convert non _INT_ giac gen")
 
-
     property _double:  # immediate double (type _DOUBLE_)
         """
         immediate conversion to float for a gen of _DOUBLE_ type.
         """
         def __get__(self):
-            if(self._type == 1):
+            if self._type == 1:
                 sig_on()
-                result=self.gptr._DOUBLE_val
+                result = self.gptr._DOUBLE_val
                 sig_off()
                 return result
             else:
@@ -1756,8 +1753,6 @@ cdef class Pygen(GiacMethods_base):
         def __get__(self):
             return self._help()
 
-
-
     ###################################################
     # Add the others methods
     ###################################################
@@ -1767,30 +1762,22 @@ cdef class Pygen(GiacMethods_base):
     #
     #     def __getattr__(self, name):
     #       return GiacMethods[str(name)](self)
-    ##
 
+    # test
 
-    #test
     def giacAiry_Ai(self, *args):
-        cdef gen result=GIAC_Airy_Ai(self.gptr[0], context_ptr)
+        cdef gen result = GIAC_Airy_Ai(self.gptr[0], context_ptr)
         return _wrap_gen(result)
 
     def giacifactor(self, *args):
         cdef gen result
         sig_on()
-        result=GIAC_eval(self.gptr[0], <int>1, context_ptr)
-        result=GIAC_ifactor(result, context_ptr)
+        result = GIAC_eval(self.gptr[0], <int>1, context_ptr)
+        result = GIAC_ifactor(result, context_ptr)
         sig_off()
         return _wrap_gen(result)
 
 
-
-
-
-
-
-
-##
 ################################################################
 #   A wrapper from a cpp element of type giac gen to create    #
 #   the Python object                                          #

src/sage/matrix/constructor.pyx

@@ -650,10 +650,13 @@ def matrix(*args, **kwds):
         M.set_immutable()
     return M
 
+
 Matrix = matrix
 
+
 from .special import *
 
+
 @matrix_method
 class options(GlobalOptions):
     r"""

src/sage/matrix/matrix0.pyx

@@ -581,26 +581,25 @@ cdef class Matrix(sage.structure.element.Matrix):
 
         self.set_unsafe(i, j, elt + self.get_unsafe(i, j))
 
-
-##     def _get_very_unsafe(self, i, j):
-##         r"""
-##         Entry access, but potentially fast since it might be without
-##         bounds checking.  (I know of no cases where this is actually
-##         faster.)
-
-##         This function it can very easily !! SEG FAULT !! if you call
-##         it with invalid input.  Use with *extreme* caution.
-
-##         EXAMPLES::
-##
-##             sage: a = matrix(ZZ,2,range(4))
-##             sage: a._get_very_unsafe(0,1)
-##             1
-
-##         If you do \code{a.\_get\_very\_unsafe(0,10)} you'll very likely crash Sage
-##         completely.
-##         """
-##         return self.get_unsafe(i, j)
+    ##     def _get_very_unsafe(self, i, j):
+    ##         r"""
+    ##         Entry access, but potentially fast since it might be without
+    ##         bounds checking.  (I know of no cases where this is actually
+    ##         faster.)
+
+    ##         This function it can very easily !! SEG FAULT !! if you call
+    ##         it with invalid input.  Use with *extreme* caution.
+
+    ##         EXAMPLES::
+    ##
+    ##             sage: a = matrix(ZZ,2,range(4))
+    ##             sage: a._get_very_unsafe(0,1)
+    ##             1
+
+    ##         If you do \code{a.\_get\_very\_unsafe(0,10)} you'll very likely crash Sage
+    ##         completely.
+    ##         """
+    ##         return self.get_unsafe(i, j)
 
     def __iter__(self):
         """
@@ -2244,11 +2243,10 @@ cdef class Matrix(sage.structure.element.Matrix):
 
         return "\\left" + matrix_delimiters[0] + "\\begin{array}{%s}\n"%format + s + "\n\\end{array}\\right" + matrix_delimiters[1]
 
-
-
     ###################################################
     ## Basic Properties
     ###################################################
+
     def ncols(self):
         """
         Return the number of columns of this matrix.
@@ -2316,22 +2314,20 @@ cdef class Matrix(sage.structure.element.Matrix):
         """
         return (self._nrows,self._ncols)
 
-
     ###################################################
     # Functions
     ###################################################
+
     def act_on_polynomial(self, f):
         r"""
         Return the polynomial f(self\*x).
 
         INPUT:
 
-
         -  ``self`` - an nxn matrix
 
         -  ``f`` - a polynomial in n variables x=(x1,...,xn)
 
-
         OUTPUT: The polynomial f(self\*x).
 
         EXAMPLES::

src/sage/matrix/matrix1.pyx

@@ -1473,10 +1473,10 @@ cdef class Matrix(Matrix0):
         tmp = [self.get_unsafe(i,j) for j in range(self._ncols)]
         return V(tmp, coerce=False, copy=False, check=False)
 
-
     ###########################################################################
     # Building matrices out of other matrices, rows, or columns
     ###########################################################################
+
     def stack(self, bottom, subdivide=False):
         r"""
         Return a new matrix formed by appending the matrix (or vector)
@@ -2539,10 +2539,9 @@ cdef class Matrix(Matrix0):
                     M.set_unsafe(i, j, one)
         return M
 
-
-    ####################################################################################
+    ######################################################################
     # Change of representation between dense and sparse.
-    ####################################################################################
+    ######################################################################
 
     def dense_matrix(self):
         """

src/sage/matrix/matrix2.pyx

@@ -115,6 +115,7 @@ def ideal_or_fractional(R, *args):
 
 _Fields = Fields()
 
+
 cdef class Matrix(Matrix1):
     """
     Base class for matrices, part 2

src/sage/matrix/matrix_cyclo_dense.pyx

@@ -814,7 +814,6 @@ cdef class Matrix_cyclo_dense(Matrix_dense):
         A._matrix = -self._matrix
         return A
 
-
     ########################################################################
     # LEVEL 3 functionality (Optional)
     #    * __deepcopy__
@@ -824,6 +823,7 @@ cdef class Matrix_cyclo_dense(Matrix_dense):
     #    * Specialized echelon form
     #    * tensor product
     ########################################################################
+
     def set_immutable(self):
         """
         Change this matrix so that it is immutable.

src/sage/matrix/matrix_integer_dense.pyx

@@ -1094,7 +1094,6 @@ cdef class Matrix_integer_dense(Matrix_dense):
         sig_off()
         return ans
 
-
     ########################################################################
     # LEVEL 3 functionality (Optional)
     #    * __deepcopy__
@@ -2743,10 +2742,9 @@ cdef class Matrix_integer_dense(Matrix_dense):
         import sage.libs.ntl.ntl_mat_ZZ
         return sage.libs.ntl.ntl_mat_ZZ.ntl_mat_ZZ(self._nrows,self._ncols, self.list())
 
-
-    ####################################################################################
+    #######################################################################
     # LLL
-    ####################################################################################
+    #######################################################################
 
     def BKZ(self, delta=None, algorithm="fpLLL", fp=None, block_size=10, prune=0,
             use_givens=False, precision=0, proof=None, **kwds):
@@ -5165,7 +5163,6 @@ cdef class Matrix_integer_dense(Matrix_dense):
         sig_free(T_rows)
         return res
 
-
     #################################################################
     # operations with matrices
     #################################################################

src/sage/matrix/matrix_mod2_dense.pyx

@@ -2057,11 +2057,13 @@ def unpickle_matrix_mod2_dense_v2(r, c, data, size, immutable=False):
 
     return A
 
+
 from sage.misc.persist import register_unpickle_override
 register_unpickle_override('sage.matrix.matrix_mod2_dense',
                            'unpickle_matrix_mod2_dense_v1',
                            unpickle_matrix_mod2_dense_v2)
 
+
 def from_png(filename):
     """
     Returns a dense matrix over GF(2) from a 1-bit PNG image read from

src/sage/matrix/matrix_rational_sparse.pyx

@@ -268,7 +268,6 @@ cdef class Matrix_rational_sparse(Matrix_sparse):
         mpq_clear(s)
         return ans
 
-
     ########################################################################
     # def _pickle(self):
     # def _unpickle(self, data, int version):   # use version >= 0
@@ -281,20 +280,21 @@ cdef class Matrix_rational_sparse(Matrix_sparse):
     # def _multiply_classical(left, matrix.Matrix _right):
     # def _list(self):
 
-# TODO
-##     cpdef _lmul_(self, Element right):
-##         """
-##         EXAMPLES::
-##
-##             sage: a = matrix(QQ,2,range(6))
-##             sage: (3/4) * a
-##             [   0  3/4  3/2]
-##             [ 9/4    3 15/4]
-##         """
+    # TODO
+    ##     cpdef _lmul_(self, Element right):
+    ##         """
+    ##         EXAMPLES::
+    ##
+    ##             sage: a = matrix(QQ,2,range(6))
+    ##             sage: (3/4) * a
+    ##             [   0  3/4  3/2]
+    ##             [ 9/4    3 15/4]
+    ##         """
 
     def _dict(self):
         """
         Unsafe version of the dict method, mainly for internal use.
+
         This may return the dict of elements, but as an *unsafe*
         reference to the underlying dict of the object.  It might
         be dangerous if you change entries of the returned dict.
@@ -313,7 +313,6 @@ cdef class Matrix_rational_sparse(Matrix_sparse):
         self.cache('dict', d)
         return d
 
-
     ########################################################################
     # LEVEL 3 functionality (Optional)
     #    * cdef _sub_
@@ -325,7 +324,7 @@ cdef class Matrix_rational_sparse(Matrix_sparse):
 
     def _nonzero_positions_by_row(self, copy=True):
         """
-        Returns the list of pairs (i,j) such that self[i,j] != 0.
+        Return the list of pairs (i,j) such that self[i,j] != 0.
 
         It is safe to change the resulting list (unless you give the option copy=False).