Added python3 support for efficient method in arrayToQPath

pyqtgraph/functions.py

@@ -1077,14 +1077,29 @@ def arrayToQPath(x, y, connect='all'):
     should be connected, or an array of int32 values (0 or 1) indicating
     connections.
     """
-    
-    ## Create all vertices in path. The method used below creates a binary format so that all 
-    ## vertices can be read in at once. This binary format may change in future versions of Qt, 
+
+    ## Create all vertices in path. The method used below creates a binary format so that all
+    ## vertices can be read in at once. This binary format may change in future versions of Qt,
     ## so the original (slower) method is left here for emergencies:
-    #path.moveTo(x[0], y[0])
-    #for i in range(1, y.shape[0]):
-    #    path.lineTo(x[i], y[i])
-        
+        #path.moveTo(x[0], y[0])
+        #if connect == 'all':
+            #for i in range(1, y.shape[0]):
+                #path.lineTo(x[i], y[i])
+        #elif connect == 'pairs':
+            #for i in range(1, y.shape[0]):
+                #if i%2 == 0:
+                    #path.lineTo(x[i], y[i])
+                #else:
+                    #path.moveTo(x[i], y[i])
+        #elif isinstance(connect, np.ndarray):
+            #for i in range(1, y.shape[0]):
+                #if connect[i] == 1:
+                    #path.lineTo(x[i], y[i])
+                #else:
+                    #path.moveTo(x[i], y[i])
+        #else:
+            #raise Exception('connect argument must be "all", "pairs", or array')
+
     ## Speed this up using >> operator
     ## Format is:
     ##    numVerts(i4)   0(i4)
@@ -1094,76 +1109,60 @@ def arrayToQPath(x, y, connect='all'):
     ##    0(i4)
     ##
     ## All values are big endian--pack using struct.pack('>d') or struct.pack('>i')
-    
+
     path = QtGui.QPainterPath()
-    
+
     #prof = debug.Profiler('PlotCurveItem.generatePath', disabled=True)
-    if sys.version_info[0] == 2:   ## So this is disabled for python 3... why??
-        n = x.shape[0]
-        # create empty array, pad with extra space on either end
-        arr = np.empty(n+2, dtype=[('x', '>f8'), ('y', '>f8'), ('c', '>i4')])
-        # write first two integers
-        #prof.mark('allocate empty')
-        arr.data[12:20] = struct.pack('>ii', n, 0)
-        #prof.mark('pack header')
-        # Fill array with vertex values
-        arr[1:-1]['x'] = x
-        arr[1:-1]['y'] = y
-        
-        # decide which points are connected by lines
-        if connect == 'pairs':
-            connect = np.empty((n/2,2), dtype=np.int32)
-            connect[:,0] = 1
-            connect[:,1] = 0
-            connect = connect.flatten()
-            
-        if connect == 'all':
-            arr[1:-1]['c'] = 1
-        elif isinstance(connect, np.ndarray):
-            arr[1:-1]['c'] = connect
-        else:
-            raise Exception('connect argument must be "all", "pairs", or array')
-            
-        #prof.mark('fill array')
-        # write last 0
-        lastInd = 20*(n+1)
-        arr.data[lastInd:lastInd+4] = struct.pack('>i', 0)
-        #prof.mark('footer')
-        # create datastream object and stream into path
-        
-        ## Avoiding this method because QByteArray(str) leaks memory in PySide
-        #buf = QtCore.QByteArray(arr.data[12:lastInd+4])  # I think one unnecessary copy happens here
-        
-        path.strn = arr.data[12:lastInd+4] # make sure data doesn't run away
-        buf = QtCore.QByteArray.fromRawData(path.strn)
-        #prof.mark('create buffer')
-        ds = QtCore.QDataStream(buf)
-            
-        ds >> path
-        #prof.mark('load')
-        
-        #prof.finish()
+    n = x.shape[0]
+    # create empty array, pad with extra space on either end
+    arr = np.empty(n+2, dtype=[('x', '>f8'), ('y', '>f8'), ('c', '>i4')])
+    # write first two integers
+    #prof.mark('allocate empty')
+    byteview = arr.view(dtype=np.ubyte)
+    byteview[:12] = 0
+    byteview.data[12:20] = struct.pack('>ii', n, 0)
+    #prof.mark('pack header')
+    # Fill array with vertex values
+    arr[1:-1]['x'] = x
+    arr[1:-1]['y'] = y
+
+    # decide which points are connected by lines
+    if connect == 'pairs':
+        connect = np.empty((n/2,2), dtype=np.int32)
+        connect[:,0] = 1
+        connect[:,1] = 0
+        connect = connect.flatten()
+
+    if connect == 'all':
+        arr[1:-1]['c'] = 1
+    elif isinstance(connect, np.ndarray):
+        arr[1:-1]['c'] = connect
     else:
-        ## This does exactly the same as above, but less efficiently (and more simply).
-        path.moveTo(x[0], y[0])
-        if connect == 'all':
-            for i in range(1, y.shape[0]):
-                path.lineTo(x[i], y[i])
-        elif connect == 'pairs':
-            for i in range(1, y.shape[0]):
-                if i%2 == 0:
-                    path.lineTo(x[i], y[i])
-                else:
-                    path.moveTo(x[i], y[i])
-        elif isinstance(connect, np.ndarray):
-            for i in range(1, y.shape[0]):
-                if connect[i] == 1:
-                    path.lineTo(x[i], y[i])
-                else:
-                    path.moveTo(x[i], y[i])
-        else:
-            raise Exception('connect argument must be "all", "pairs", or array')
-            
+        raise Exception('connect argument must be "all", "pairs", or array')
+
+    #prof.mark('fill array')
+    # write last 0
+    lastInd = 20*(n+1)
+    byteview.data[lastInd:lastInd+4] = struct.pack('>i', 0)
+    #prof.mark('footer')
+    # create datastream object and stream into path
+
+    ## Avoiding this method because QByteArray(str) leaks memory in PySide
+    #buf = QtCore.QByteArray(arr.data[12:lastInd+4])  # I think one unnecessary copy happens here
+
+    path.strn = byteview.data[12:lastInd+4] # make sure data doesn't run away
+    try:
+        buf = QtCore.QByteArray.fromRawData(path.strn)
+    except TypeError:
+        buf = QtCore.QByteArray(bytes(path.strn))
+    #prof.mark('create buffer')
+    ds = QtCore.QDataStream(buf)
+
+    ds >> path
+    #prof.mark('load')
+
+    #prof.finish()
+
     return path
 
 #def isosurface(data, level):