From 6c142046828125b386e7f76c42da62bae1668ff6 Mon Sep 17 00:00:00 2001
From: Nils Nemitz <nils.nemitz@gmx.de>
Date: Thu, 19 Nov 2020 02:31:28 +0900
Subject: [PATCH] Fix set empty (#1446)

* changes to setData and dataRect to handle setting empty data

* simplified named argument check

* tests for clearing PlotDataItem by setData() and setData([],[]), commented out vestigal xClean/yClean

* removed last remains of xClean/yClean
---
 pyqtgraph/graphicsItems/PlotDataItem.py       | 43 +++++++++----------
 .../graphicsItems/tests/test_PlotDataItem.py  | 14 +++++-
 2 files changed, 33 insertions(+), 24 deletions(-)

diff --git a/pyqtgraph/graphicsItems/PlotDataItem.py b/pyqtgraph/graphicsItems/PlotDataItem.py
index 30f745d1..b583bc94 100644
--- a/pyqtgraph/graphicsItems/PlotDataItem.py
+++ b/pyqtgraph/graphicsItems/PlotDataItem.py
@@ -226,7 +226,6 @@ class PlotDataItem(GraphicsObject):
             return
         self.opts['fftMode'] = mode
         self.xDisp = self.yDisp = None
-        self.xClean = self.yClean = None
         self.updateItems()
         self.informViewBoundsChanged()
 
@@ -235,7 +234,6 @@ class PlotDataItem(GraphicsObject):
             return
         self.opts['logMode'] = [xMode, yMode]
         self.xDisp = self.yDisp = None
-        self.xClean = self.yClean = None
         self.updateItems()
         self.informViewBoundsChanged()
 
@@ -245,7 +243,6 @@ class PlotDataItem(GraphicsObject):
             return
         self.opts['derivativeMode'] = mode
         self.xDisp = self.yDisp = None
-        self.xClean = self.yClean = None
         self.updateItems()
         self.informViewBoundsChanged()
 
@@ -254,7 +251,6 @@ class PlotDataItem(GraphicsObject):
             return
         self.opts['phasemapMode'] = mode
         self.xDisp = self.yDisp = None
-        self.xClean = self.yClean = None
         self.updateItems()
         self.informViewBoundsChanged()
 
@@ -470,8 +466,12 @@ class PlotDataItem(GraphicsObject):
 
         if 'x' in kargs:
             x = kargs['x']
+            if dataType(x) == 'MetaArray':
+                x = x.asarray()
         if 'y' in kargs:
             y = kargs['y']
+            if dataType(y) == 'MetaArray':
+                y = y.asarray()
 
         profiler('interpret data')
         ## pull in all style arguments.
@@ -506,23 +506,22 @@ class PlotDataItem(GraphicsObject):
                 #self.opts[k] = kargs[k]
             #scatterArgs[v] = self.opts[k]
 
-
-        if y is None:
-            self.updateItems()
-            profiler('update items')
-            return
-        if y is not None and x is None:
-            x = np.arange(len(y))
-
-        if not isinstance(x, np.ndarray):
-            x = np.array(x)
-        if not isinstance(y, np.ndarray):
-            y = np.array(y)
-
-        self.xData = x.view(np.ndarray)  ## one last check to make sure there are no MetaArrays getting by
-        self.yData = y.view(np.ndarray)
+        if y is None or len(y) == 0: # empty data is represented as None
+            self.yData = None
+        else: # actual data is represented by ndarray
+            if not isinstance(y, np.ndarray):
+                y = np.array(y)
+            self.yData = y.view(np.ndarray)
+            if x is None:
+                x = np.arange(len(y))
+                
+        if x is None or len(x)==0: # empty data is represented as None
+            self.xData = None
+        else: # actual data is represented by ndarray
+            if not isinstance(x, np.ndarray):
+                x = np.array(x)
+            self.xData = x.view(np.ndarray)  # one last check to make sure there are no MetaArrays getting by
         self._dataRect = None
-        self.xClean = self.yClean = None
         self.xDisp = None
         self.yDisp = None
         profiler('set data')
@@ -683,6 +682,8 @@ class PlotDataItem(GraphicsObject):
             return self._dataRect
         if self.xData is None or self.yData is None:
             return None
+        if len(self.xData) == 0: # avoid crash if empty data is represented by [] instead of None
+            return None
         with warnings.catch_warnings(): 
             # All-NaN data is handled by returning None; Explicit numpy warning is not needed.
             warnings.simplefilter("ignore")
@@ -751,8 +752,6 @@ class PlotDataItem(GraphicsObject):
         #self.scatters = []
         self.xData = None
         self.yData = None
-        #self.xClean = None
-        #self.yClean = None
         self.xDisp = None
         self.yDisp = None
         self._dataRect = None
diff --git a/pyqtgraph/graphicsItems/tests/test_PlotDataItem.py b/pyqtgraph/graphicsItems/tests/test_PlotDataItem.py
index 926b6098..d58db91e 100644
--- a/pyqtgraph/graphicsItems/tests/test_PlotDataItem.py
+++ b/pyqtgraph/graphicsItems/tests/test_PlotDataItem.py
@@ -42,6 +42,11 @@ def test_setData():
     pdi.setData(x, y)
     assert len(pdi.xData) == 150
     assert len(pdi.yData) == 150
+    
+    #test clear by empty call
+    pdi.setData()
+    assert pdi.xData is None
+    assert pdi.yData is None
 
     #test dict of x, y list
     y += list(np.random.normal(size=50))
@@ -50,14 +55,19 @@ def test_setData():
     assert len(pdi.xData) == 200
     assert len(pdi.yData) == 200
 
+    #test clear by zero length arrays call
+    pdi.setData([],[])
+    assert pdi.xData is None
+    assert pdi.yData is None
+
 def test_clear():
     y = list(np.random.normal(size=100))
     x = np.linspace(5, 10, 100)
     pdi = pg.PlotDataItem(x, y)
     pdi.clear()
 
-    assert pdi.xData == None
-    assert pdi.yData == None
+    assert pdi.xData is None
+    assert pdi.yData is None
 
 def test_clear_in_step_mode():
     w = pg.PlotWidget()