Merge pull request #411 from martindurant/notebook_no_ipywidgets

Display in notebook without ipywidgets

Author: martindurant

streamz/collection.py

@@ -239,8 +239,17 @@ def stop(self):
         self.stream.stop()
 
     def _ipython_display_(self, **kwargs):
-        return self.stream.latest().rate_limit(
-            0.5).gather()._ipython_display_(**kwargs)
+        try:
+            from ipywidgets import Output  # noqa: F401
+            return self.stream.latest().rate_limit(
+                0.5).gather()._ipython_display_(**kwargs)
+        except ImportError:
+            # since this function is only called by jupyter, this import must succeed
+            from IPython.display import display, HTML
+            if hasattr(self, '_repr_html_'):
+                return display(HTML(self._repr_html_()))
+            else:
+                return display(self.__repr__())
 
     def emit(self, x):
         self.verify(x)

streamz/core.py

@@ -1,5 +1,4 @@
 from __future__ import absolute_import, division, print_function
-
 from collections import deque, defaultdict
 from datetime import timedelta
 import functools
@@ -385,14 +384,16 @@ def __str__(self):
 
     def _ipython_display_(self, **kwargs):  # pragma: no cover
         try:
-            from ipywidgets import Output
+            import ipywidgets
             from IPython.core.interactiveshell import InteractiveShell
+            output = ipywidgets.Output(_view_count=0)
         except ImportError:
+            # since this function is only called by jupyter, this import must succeed
+            from IPython.display import display, HTML
             if hasattr(self, '_repr_html_'):
-                return self._repr_html_()
+                return display(HTML(self._repr_html_()))
             else:
-                return self.__repr__()
-        output = Output(_view_count=0)
+                return display(self.__repr__())
         output_ref = weakref.ref(output)
 
         def update_cell(val):

streamz/dataframe/tests/test_dataframes.py

@@ -344,6 +344,24 @@ def test_repr_html(stream):
         assert '1' in html
 
 
+def test_display(monkeypatch, capsys):
+    pytest.importorskip("ipywidgets")
+    import ipywidgets
+    df = pd.DataFrame({'x': (np.arange(10) // 2).astype(float), 'y': [1.0] * 10})
+    a = DataFrame(example=df, stream=stream)
+
+    # works by side-affect of display()
+    a._ipython_display_()
+    assert "Output()" in capsys.readouterr().out
+
+    def get(*_, **__):
+        raise ImportError
+    monkeypatch.setattr(ipywidgets.Output, "__init__", get)
+
+    out = source._ipython_display_()
+    assert "DataFrame" in capsys.readouterr().out
+
+
 def test_setitem(stream):
     df = pd.DataFrame({'x': list(range(10)), 'y': [1] * 10})
 

streamz/tests/test_core.py

@@ -1016,6 +1016,25 @@ def add(x=0, y=0):
     assert str(s) == '<map: add>'
 
 
+def test_no_ipywidget_repr(monkeypatch, capsys):
+    pytest.importorskip("ipywidgets")
+    import ipywidgets
+    source = Stream()
+
+    # works by side-affect of display()
+    source._ipython_display_()
+    assert "Output()" in capsys.readouterr().out
+
+    def get(*_, **__):
+        raise ImportError
+    monkeypatch.setattr(ipywidgets.Output, "__init__", get)
+
+    out = source._ipython_display_()
+    assert "Stream" in capsys.readouterr().out
+
+
+
+
 def test_filter_str():
     def iseven(x):
         return x % 2 == 0