Update clipboard Qt-bindings for flexiblity and Python3 compatibility

doc/source/install.rst

@@ -251,7 +251,8 @@ Optional Dependencies
 * `Jinja2 <http://jinja.pocoo.org/>`__: Template engine for conditional HTML formatting.
 * `s3fs <http://s3fs.readthedocs.io/>`__: necessary for Amazon S3 access (s3fs >= 0.0.7).
 * `blosc <https://pypi.python.org/pypi/blosc>`__: for msgpack compression using ``blosc``
-* One of `PyQt4
+* One of `PyQt5
+  <https://www.riverbankcomputing.com/software/pyqt/download5>`__, `PyQt4
   <http://www.riverbankcomputing.com/software/pyqt/download>`__, `PySide
   <http://qt-project.org/wiki/Category:LanguageBindings::PySide>`__, `pygtk
   <http://www.pygtk.org/>`__, `xsel

doc/source/io.rst

@@ -3053,7 +3053,7 @@ We can see that we got the same content back, which we had earlier written to th
 
 .. note::
 
-   You may need to install xclip or xsel (with gtk or PyQt4 modules) on Linux to use these methods.
+   You may need to install xclip or xsel (with gtk, PyQt5, PyQt4 or qtpy) on Linux to use these methods.
 
 .. _io.pickle:
 

doc/source/whatsnew/v0.22.0.txt

@@ -127,6 +127,7 @@ I/O
 - Bug in :func:`read_msgpack` with a non existent file is passed in Python 2 (:issue:`15296`)
 - Bug in :func:`read_csv` where a ``MultiIndex`` with duplicate columns was not being mangled appropriately (:issue:`18062`)
 - Bug in :func:`read_sas` where a file with 0 variables gave an ``AttributeError`` incorrectly. Now it gives an ``EmptyDataError`` (:issue:`18184`)
+- :func:`pandas.read_clipboard` updated to use qtpy, falling back to PyQt5 and then PyQt4, adding compatibility with Python3 and multiple python-qt bindings (:issue:`17722`)
 -
 -
 

pandas/io/clipboard/__init__.py

@@ -18,7 +18,8 @@
 On Linux, install xclip or xsel via package manager. For example, in Debian:
 sudo apt-get install xclip
 
-Otherwise on Linux, you will need the gtk or PyQt4 modules installed.
+Otherwise on Linux, you will need the gtk, qtpy or PyQt modules installed.
+qtpy also requires a python-qt-bindings module: PyQt4, PyQt5, PySide, PySide2
 
 gtk and PyQt4 modules are not available for Python 3,
 and this module does not work with PyGObject yet.
@@ -34,9 +35,9 @@
                          init_klipper_clipboard, init_no_clipboard)
 from .windows import init_windows_clipboard
 
-# `import PyQt4` sys.exit()s if DISPLAY is not in the environment.
+# `import qtpy` sys.exit()s if DISPLAY is not in the environment.
 # Thus, we need to detect the presence of $DISPLAY manually
-# and not load PyQt4 if it is absent.
+# and not load qtpy if it is absent.
 HAS_DISPLAY = os.getenv("DISPLAY", False)
 CHECK_CMD = "where" if platform.system() == "Windows" else "which"
 
@@ -68,9 +69,23 @@ def determine_clipboard():
             return init_gtk_clipboard()
 
         try:
-            # Check if PyQt4 is installed
-            import PyQt4  # noqa
+            # qtpy is a small abstraction layer that lets you write
+            # applications using a single api call to either PyQt or PySide
+            # https://pypi.python.org/pypi/QtPy
+            import qtpy  # noqa
         except ImportError:
+            # If qtpy isn't installed, fall back on importing PyQt5, or PyQt5
+            try:
+                import PyQt5  # noqa
+            except ImportError:
+                try:
+                    import PyQt4  # noqa
+                except ImportError:
+                    pass  # fail fast for all non-ImportError exceptions.
+                else:
+                    return init_qt_clipboard()
+            else:
+                return init_qt_clipboard()
             pass
         else:
             return init_qt_clipboard()

pandas/io/clipboard/clipboards.py

@@ -46,10 +46,19 @@ def paste_gtk():
 
 def init_qt_clipboard():
     # $DISPLAY should exist
-    from PyQt4.QtGui import QApplication
 
-    # use the global instance if it exists
-    app = QApplication.instance() or QApplication([])
+    # Try to import from qtpy, but if that fails try PyQt5 then PyQt4
+    try:
+        from qtpy.QtWidgets import QApplication
+    except ImportError:
+        try:
+            from PyQt5.QtWidgets import QApplication
+        except ImportError:
+            from PyQt4.QtGui import QApplication
+
+    app = QApplication.instance()
+    if app is None:
+        app = QApplication([])
 
     def copy_qt(text):
         cb = app.clipboard()