make matplotlib an optional dependency

README.rst

@@ -117,7 +117,9 @@ The user can quickly create a PV array with ``pvfactors``, and manipulate it wit
               df_inputs.albedo)
 
 The user can then plot the PV array geometry at any given time of the simulation:
-
+Please note that the plot is generated using matplotlib, which is
+not included in the default dependencies, it can be installed
+using `pip install solarfactors[plot]`
 
 .. code:: python
 

docs/sphinx/whatsnew/v1.6.2.rst

@@ -0,0 +1,17 @@
+.. _whatsnew_162:
+
+v1.6.2 (??)
+==========
+
+
+Maintenance
+-----------
+* Matplotlib is now an optional dependency. (:issue:`31`)
+
+
+Documentation
+-------------
+
+Contributors
+------------
+* Kurt Rhee (:ghuser:`kurt-rhee`)

pvfactors/geometry/_optional_imports.py

@@ -0,0 +1,68 @@
+"""Utility module for handling optional dependencies for plotting functionality."""
+
+import functools
+
+
+def _matplotlib_import_error_message():
+    """Generate helpful error message for missing matplotlib."""
+    return (
+        "matplotlib is required for plotting functionality. "
+        "Install it using one of the following methods:\n"
+        "  pip install solarfactors[plot]\n"
+        "  pip install matplotlib\n"
+        "  conda install matplotlib"
+    )
+
+
+def _check_matplotlib():
+    """
+    Check if matplotlib is available and raise ImportError if not.
+    """
+    try:
+        import matplotlib  # noqa: F401
+
+        return True
+    except ImportError:
+        raise ImportError(_matplotlib_import_error_message())
+
+
+def requires_matplotlib(func):
+    """Decorator to check for matplotlib availability before executing
+    plotting functions.
+
+    Parameters
+    ----------
+    func : callable
+        Function that requires matplotlib
+
+    Returns
+    -------
+    callable
+        Wrapped function that checks for matplotlib before execution
+    """
+
+    @functools.wraps(func)
+    def wrapper(*args, **kwargs):
+        _check_matplotlib()
+        return func(*args, **kwargs)
+
+    return wrapper
+
+
+def optional_matplotlib_import():
+    """Import matplotlib.pyplot with optional handling.
+
+    Returns
+    -------
+    module or None
+        matplotlib.pyplot module if available, None otherwise
+
+    Raises
+    ------
+    ImportError
+        If matplotlib is not available with helpful installation message
+    """
+    _check_matplotlib()
+    import matplotlib.pyplot as plt  # noqa: F401
+
+    return plt