sage.graphs, sage.numerical.mip: Remove unnecessary uses of set_binary, set_integer

[mkoeppe]

We can avoid these methods that mutate variable type by setting up the correct variable type in the first place.

CC: @dcoudert

Component: linear programming

Author: Matthias Koeppe

Branch/Commit: b82a512

Reviewer: Travis Scrimshaw, David Coudert

Issue created by migration from https://trac.sagemath.org/ticket/33504

[mkoeppe]

Branch: u/mkoeppe/sage_graphs__sage_numerical_mip__remove_unnecessary_uses_of_set_binary__set_integer

[mkoeppe]

New commits:

cbfeef2	MIPVariable: Avoid using _backend.set_variable_type
6c1a8f5	vertex_separation_MILP: Remove redundant call of set_binary
44e219f	GenericGraph.multicommodity_flow: Directly create MIP variables as integers, do not use set_integer

[mkoeppe]

Author: Matthias Koeppe

[mkoeppe]

Commit: 44e219f

[tscrim]

comment:3

LGTM. Green bot => positive review.

[tscrim]

Reviewer: Travis Scrimshaw

[dcoudert]

comment:4

You did

-        flow = p.new_variable(nonnegative=True)
+        if integer:
+            flow = p.new_variable(nonnegative=True, integer=True)
+        else:
+            flow = p.new_variable(nonnegative=True)

but why not simply

-        flow = p.new_variable(nonnegative=True)
+        flow = p.new_variable(nonnegative=True, integer=integer is True)

[sheerluck]

comment:5

Replying to @dcoudert:

flow = p.new_variable(nonnegative=True, integer=integer is True)

flow = p.new_variable(nonnegative=True, integer=integer)

[sagetrac-git]

Changed commit from 44e219f to b82a512

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

b82a512

GenericGraph.multicommodity_flow: Simplify

[mkoeppe]

comment:7

Thanks, done

[dcoudert]

Changed reviewer from Travis Scrimshaw to Travis Scrimshaw, David Coudert

[dcoudert]

comment:8

Green bot