Fixing typos in scip.pyx file

.gitignore

@@ -115,3 +115,14 @@ venv.bak/
 
 # mypy
 .mypy_cache/
+
+# pytest
+.pytest_cache/
+
+# model (for tests)
+model
+model.cip
+model.lp
+
+# VSCode
+.vscode/

.travis.yml

@@ -1,31 +1,37 @@
+os: linux
+dist: xenial
+sudo: true
+
 language: python
 
 python:
-  - '2.7'
-  - '3.6'
+  - 2.7
+  - 3.5
+  - 3.6
+  - 3.7
+
+env:
+  global:
+    - secure: "CML6W6GUTFcZxZavt2x9vT3pUeg9jA2tber8Wl+34zBI9QxXel8PxKlw896OI2jnGPMvL7ANRElklE6/WNaVvogjgZXKcXnqaGKPoPlJNsGenHw0poxjqrrs9VnuX2XU56h53ESsOZ9mq53oFNaimS6fbtIAs7xlS27nY0KJk42ZEicaS2E9cbzH/XqOIEzdIZCHy8NjViMXFCspE9fhndv04T3ic2opXmGDy2veoZ/oF2zbOcz0e9XLEjTs0yXz5qir8AGEnRS4lwI6hb3jkMBOxbNKIPx63gsno3xUHjXYjiwb4iQV9eybhY0csli/5br8isIX81vlg5xeoEfvSy6sZvZ8rErx3Eos5OdCu4vnxqtMZvpb+2pCVQU2IldZTl9B3/lv4ehZhKurF3l89rnqKW14eh4p2eT6WQ2s0tjPd5NuPdow4hT5x7WWSeS1395exlJJGgv1bt4ASM+KNFfA/4CK4TjszZJ7xLttiJ7nOgo/8KtSd/dM0PfBWeeBQxi/0YgCyD781ieL009ZUPwvKf4B0RJ8pPaSDePypKHvzmcm7UGgT86zz1FnCxsIEmHFJQGazXbdBmi0OvPAo1fCrAdMXipppf+ckAotckWjOLIK6IN9RlrF/E9YFll/SfSiXi6EdB0P+T6m8iBqNEToJbUiRqKhMznr7A4+JLs="
+    - VERSION=6.0.0
 
 notifications:
   email: false
 
 before_install:
-  - export VERSION=5.0.1
-  - wget http://scip.zib.de/download/release/scipoptsuite-$VERSION.tgz
-  - tar xf scipoptsuite-$VERSION.tgz
-  - cd scipoptsuite-$VERSION
-  - mkdir build
-  - cd build; cmake .. -DCMAKE_C_STANDARD=99 -DCMAKE_INSTALL_PREFIX=~/scipdir; make -j8 install; cd ..
-  - cd ..
-  - rm -rf scipoptsuite-$VERSION
+  - sudo apt-get install libblas-dev liblapack-dev gfortran
+  - export VERSION=6.0.0
+  - wget http://scip.zib.de/download/release/SCIPOptSuite-$VERSION-Linux.deb
+  - sudo dpkg -i SCIPOptSuite-$VERSION-Linux.deb
 
 install:
-  - pip install cython networkx pytest-cov codecov
-  - # SCIPOPTDIR=~/scipdir python setup.py build_ext --inplace --define CYTHON_TRACE
-  - SCIPOPTDIR=~/scipdir python setup.py install
+  - pip install cython networkx pytest-cov
+  - python setup.py install
 
-script: py.test --cov
+script: py.test #--cov
 
-after_success:
-  - codecov
+# after_success:
+  # - codecov
 
 deploy:
   provider: pypi
@@ -34,3 +40,4 @@ deploy:
     secure: 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
   on:
     tags: true
+  skip_existing: true

CONTRIBUTING.rst

@@ -0,0 +1,52 @@
+Contributing to PySCIPOpt
+=========================
+
+Code contributions are very welcome and should comply to a few rules:
+
+0. Read `Design principles of PySCIPOpt`_.
+
+1. Compatibility with both Python-2 and Python-3.
+
+2. All tests defined in the Continuous Integration setup need to pass:
+
+   - `.travis.yml <.travis.yml>`__
+   - `appveyor.yml <appveyor.yml>`__
+
+3. New features should be covered by tests *and* examples. Please extend `tests <tests>`__ and `examples <examples>`__. Tests uses pytest and examples are meant to be accessible for PySCIPOpt newcomers (even advanced examples).
+
+4. New code should be documented in the same style as the rest of the code.
+
+5. New code should be `pep8-compliant <https://www.python.org/dev/peps/pep-0008/>`__. Help yourself with the `style guide checker <https://pypi.org/project/pep8/>`__.
+
+6. Before implementing a new PySCIPOpt feature, check whether the feature exists in SCIP. If so, implement it as a pure wrapper, mimicking SCIP whenever possible. If the new feature does not exist in SCIP but it is close to an existing one, consider if implementing that way is substantially convenient (e.g. Pythonic). If it does something completely different, you are welcome to pull your request and discuss the implementation.
+
+7. PySCIPOpt uses `semantic versioning <https://semver.org/>`__. Version number increase only happens on master and must be tagged to build a new PyPI release.
+
+For general reference, we suggest:
+
+- `PySCIPOpt README <README.rst>`__;
+- `SCIP documentation <http://scip.zib.de/doc/html/>`__;
+- `SCIP mailing list <https://listserv.zib.de/mailman/listinfo/scip/>`__ which can be easily searched with search engines (e.g. `Google <http://www.google.com/#q=site:listserv.zib.de%2Fpipermail%2Fscip>`__);
+- `open and closed PySCIPOpt issues <https://github.com/SCIP-Interfaces/PySCIPOpt/issues?utf8=%E2%9C%93&q=is%3Aissue>`__;
+- `SCIP/PySCIPOpt Stack Exchange <https://stackoverflow.com/questions/tagged/scip>`__.
+
+If you find this contributing guide unclear, please open an issue! :)
+
+Design principles of PySCIPOpt
+==============================
+
+PySCIPOpt is meant to be a fast-prototyping interface of the pure SCIP C API. By design, we distinguish different functions in PySCIPOPT:
+
+- pure wrapping functions of SCIP;
+- convenience functions.
+
+**PySCIPOpt wrappers of SCIP functions** should act:
+
+- with an expected behavior - and parameters, returns, attributes, ... - as close to SCIP as possible
+- without *"breaking"* Python and the purpose for what the language it is meant.
+
+Ideally speaking, we want every SCIP function to be wrapped in PySCIPOpt.
+
+**Convenience functions** are additional, non-detrimental features meant to help prototyping the Python way. Since these functions are not in SCIP, we wish to limit them to prevent difference in features between SCIP and PySCIPOPT, which are always difficult to maintain. A few convenience functions survive in PySCIPOpt when keeping them is doubtless beneficial.
+
+Admittedly, *there is a middle ground where functions are not completely wrappers or just convenient*. That is the case, for instance, of fundamental :code:`Model` methods like :code:`addCons` or :code:`writeProblem`. We want to leave their development to negotiation.

INSTALL.rst

@@ -44,7 +44,7 @@ your ``PATH`` environment variable:
 
 On Linux and OS X this is encoded in the generated PySCIPOpt library and therefore not necessary.
 
-Building everything form source
+Building everything from source
 ===============================
 
 PySCIPOpt requires `Cython <http://cython.org/>`__, at least version 0.21 (``pip install cython``).
@@ -76,3 +76,26 @@ To use debug information in PySCIPOpt you need to build it like this:
 
 Be aware that you will need the **debug library** of the SCIP Optimization
 Suite for this to work (``cmake .. -DCMAKE_BUILD_TYPE=Debug``).
+
+Testing new installation
+========================
+
+To test your brand-new installation of PySCIPOpt you need `pytest <https://pytest.org/>`__ on your system. Here is the `installation procedure <https://docs.pytest.org/en/latest/getting-started.html>`__.
+
+Tests can be run in the ``PySCIPOpt`` directory with:
+::
+
+   py.test # all the available tests
+   py.test tests/test_name.py # a specific tests/test_name.py (Unix)
+
+Ideally, the status of your tests must be passed or skipped. Running tests with pytest creates the ``__pycache__`` directory in ``tests`` and, occasionally, a ``model`` file in the working directory. They can be removed harmlessly.
+
+Common errors
+=============
+
+- readline: ``libreadline.so.6: undefined symbol: PC``
+  This is a readline/ncurses compatibility issue that can be fixed like this (when using ``conda``):
+
+  ::
+
+    conda install -c conda-forge readline=6.2

README.rst

@@ -60,12 +60,12 @@ simple examples.
 Please notice that in most cases one needs to use a ``dictionary`` to
 specify the return values needed by SCIP.
 
-Extend the interface
-====================
+Extending the interface
+=======================
 
-The interface python-scip already provides many of the SCIP callable
-library methods. You may also extend python-scip to increase the
-functionality of this interface.The following will provide some
+PySCIPOpt already covers many of the SCIP callable
+library methods. You may also extend it to increase the
+functionality of this interface. The following will provide some
 directions on how this can be achieved:
 
 The two most important files in PySCIPOpt are the ``scip.pxd`` and
@@ -87,6 +87,10 @@ functions in python that reference the SCIP public functions included in
 ``scip.pxd``. This is achieved by modifying the ``scip.pyx`` file to add
 the functionality you require.
 
+We are always happy to accept pull request containing patches or extensions!
+
+Please have a look at our `contribution guidelines <CONTRIBUTING.rst>`__.
+
 Gotchas
 =======
 
@@ -122,9 +126,10 @@ Dual values
 -----------
 
 While PySCIPOpt supports access to the dual values of a solution, there are some limitations involved:
- 
+
 - Can only be used when presolving and propagation is disabled to ensure that the LP solver - which is providing the dual information - actually solves the unmodified problem.
 - Heuristics should also be disabled to avoid that the problem is solved before the LP solver is called.
+- There should be no bound constraints, i.e., constraints with only one variable. This can cause incorrect values as explained in `#136 <https://github.com/SCIP-Interfaces/PySCIPOpt/issues/136>`__
 
 Therefore, you should use the following settings when trying to work with dual information:
 

appveyor.yml

@@ -1,13 +1,11 @@
 version: '{build}'
 
-branches:
-  only:
-  - master
-
 environment:
   SCIPOPTDIR: C:\scipoptdir
-  password:
+  pypipw:
     secure: HEa8MAJyyfSv33snyK3Gleflk9SIfZBxbnTiS39hlWM=
+  optipw:
+    secure: mi/mkS8vYK1Yza0A1FB4/Q==
 
   matrix:
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
@@ -28,7 +26,12 @@ environment:
       TWINE: C:\Python36-x64\Scripts\twine
 
 install:
-  - ps: wget http://scip.zib.de/download/release/SCIPOptSuite-5.0.1-win64-VS15.exe -outfile scipopt-installer.exe
+  # - ps: $uri = 'http://opti-test.zib.de/v600-rc06/scip/download/release/SCIPOptSuite-6.0.0-win64-VS15.exe'
+  # - ps: $user = 'opti-test'
+  # - ps: $pass = $env:optipw | ConvertTo-SecureString -AsPlainText -Force
+  # - ps: $cred = New-Object Management.Automation.PSCredential ($user, ($pass))
+  # - ps: Invoke-WebRequest -Uri $uri -Credential $cred -OutFile 'scipopt-installer.exe'
+  - ps: wget http://scip.zib.de/download/release/SCIPOptSuite-6.0.0-win64-VS15.exe -outfile scipopt-installer.exe
   - scipopt-installer.exe /S /D=%SCIPOPTDIR%
   - set PATH=%SCIPOPTDIR%\bin;%PYTHON%;%PATH%
   - if [%INCLUDE_REQUIRED%]==[true] copy .\VC9-include\* %SCIPOPTDIR%\include
@@ -46,7 +49,7 @@ artifacts:
 after_test:
   - cmd: "echo [pypi] > %USERPROFILE%\\.pypirc"
   - cmd: "echo username: pyscipopt >> %USERPROFILE%\\.pypirc"
-  - cmd: "echo password: %password% >> %USERPROFILE%\\.pypirc"
+  - cmd: "echo password: %pypipw% >> %USERPROFILE%\\.pypirc"
   - python setup.py bdist_wheel
 
 on_success:

examples/finished/eoq_en.py

@@ -1,5 +1,5 @@
 """
-eoq.py:  piecewise linear model to the multi-item economic ordering quantity problem.
+eoq_en.py:  piecewise linear model to the multi-item economic ordering quantity problem.
 
 Approach: use a convex combination formulation.
 

examples/finished/even.py

@@ -0,0 +1,72 @@
+from pyscipopt import Model
+
+################################################################################
+#
+# EVEN OR ODD?
+#
+# If a positional argument is given:
+#   prints if the argument is even/odd/neither
+# else:
+#   prints if a value is even/odd/neither per each value in a example list
+#
+# This example is made for newcomers and motivated by:
+# - modulus is unsupported for pyscipopt.scip.Variable and int
+# - variables are non-integer by default
+# Based on this:
+# https://github.com/SCIP-Interfaces/PySCIPOpt/issues/172#issuecomment-394644046
+#
+################################################################################
+
+verbose = False
+sdic = {0:"even",1:"odd"}
+
+def parity(number):
+    try:
+        assert number == int(round(number))
+        m = Model()
+        m.hideOutput()
+
+        ### variables are non-negative by default since 0 is the default lb.
+        ### To allow for negative values, give None as lower bound
+        ### (None means -infinity as lower bound and +infinity as upper bound)
+        x = m.addVar("x", vtype="I", lb=None, ub=None) #ub=None is default
+        n = m.addVar("n", vtype="I", lb=None)
+        s = m.addVar("s", vtype="B")
+
+        ### CAVEAT: if number is negative, x's lb must be None
+        ### if x is set by default as non-negative and number is negative:
+        ###     there is no feasible solution (trivial) but the program
+        ###     does not highlight which constraints conflict.
+        m.addCons(x==number)
+
+        m.addCons(s == x-2*n)
+        m.setObjective(s)
+        m.optimize()
+
+        assert m.getStatus() == "optimal"
+        if verbose:
+            for v in m.getVars():
+                print("%s %d" % (v,m.getVal(v)))
+            print("%d%%2 == %d?" % (m.getVal(x), m.getVal(s)))
+            print(m.getVal(s) == m.getVal(x)%2)
+
+        xval = m.getVal(x)
+        sval = m.getVal(s)
+        sstr = sdic[sval]
+        print("%d is %s" % (xval, sstr))
+    except (AssertionError, TypeError):
+        print("%s is neither even nor odd!" % number.__repr__())
+
+if __name__ == "__main__":
+    import sys
+    from ast import literal_eval as leval
+    example_values = [0, 1, 1.5, "hallo welt", 20, 25, -101, -15., -10, -int(2**31), int(2**31-1), int(2**63)-1]
+    try:
+        try:
+            n = leval(sys.argv[1])
+        except ValueError:
+            n = sys.argv[1]
+        parity(n)
+    except IndexError:
+        for n in example_values:
+            parity(n)