Refine graph implemented in #101. (#108)

Author: tobiasraabe

docs/changes.rst

@@ -24,7 +24,8 @@ all releases are available on `PyPI <https://pypi.org/project/pytask>`_ and
 - :gh:`94` adds ``--show-locals`` which allows to print local variables in tracebacks.
 - :gh:`96` implements a spinner to show the progress during the collection.
 - :gh:`99` enables color support in WSL and fixes ``show_locals`` during collection.
-- :gh:`101` allows to visualize the project's DAG.
+- :gh:`101` implement to visualize the project's DAG. :gh:`108` refines the
+  implementation.
 - :gh:`102` adds an example if a parametrization provides not the number of arguments
   specified in the signature.
 - :gh:`105` simplifies the logging of the tasks.

docs/tutorials/how_to_visualize_the_dag.rst

@@ -1,7 +1,15 @@
 How to visualize the DAG
 ========================
 
-pytask offers two interfaces to visualize the :term:`DAG` of your project.
+To visualize the :term:`DAG` of the project, first, install `pydot
+<https://github.com/pydot/pydot>`_ and `graphviz <https://graphviz.org/>`_. For example,
+you can both install with conda
+
+.. code-block:: console
+
+    $ conda install -c conda-forge pydot
+
+After that, pytask offers two interfaces to visualize the :term:`DAG` of your project.
 
 
 Command line interface

environment.yml

@@ -30,6 +30,7 @@ dependencies:
   - matplotlib
   - pdbpp
   - pre-commit
+  - pydot
   - pytest
   - pytest-cov
   - tox-conda

src/_pytask/graph.py

@@ -191,12 +191,14 @@ def _write_graph(dag: nx.DiGraph, path: Path, layout: str) -> None:
     except ImportError:
         raise ImportError(
             "To visualize the project's DAG you need to install pydot which is "
-            "available with pip and conda."
+            "available with pip and conda. For example, use 'conda install -c "
+            "conda-forge pydot'."
         ) from None
     if shutil.which(layout) is None:
         raise RuntimeError(
-            "The layout program '{layout}' could not be found on your PATH. Please, "
-            "install graphviz. It is, for example, available with conda."
+            f"The layout program '{layout}' could not be found on your PATH. Please, "
+            "install graphviz. For example, use 'conda install -c conda-forge "
+            "graphivz'."
         )
 
     path.parent.mkdir(exist_ok=True, parents=True)