Handle axis SI prefix scaling in MatplotlibExporter (#1282)

* Handle axis SI prefix scaling in MatplotlibExporter

* Added some MatplotlibExporter tests and added matplotlib to CI deps

* Install mpl with pip instead of conda

* Cleanup

azure-test-template.yml

@@ -106,8 +106,9 @@ jobs:
         fi      
         conda info
         conda install $(qt.bindings) numpy scipy pyopengl h5py six --yes --quiet
+        pip install matplotlib
       else
-        pip install $(qt.bindings) numpy scipy pyopengl h5py six
+        pip install $(qt.bindings) numpy scipy pyopengl h5py six matplotlib
       fi
       pip install pytest pytest-cov coverage pytest-xdist
       if [ $(python.version) == "2.7" ]

pyqtgraph/exporters/Matplotlib.py

@@ -1,3 +1,4 @@
+# -*- coding: utf-8 -*-
 from ..Qt import QtGui, QtCore
 from .Exporter import Exporter
 from .. import PlotItem
@@ -31,6 +32,7 @@ publication. Fonts are not vectorized (outlined), and window colors are white.
 class MatplotlibExporter(Exporter):
     Name = "Matplotlib Window"
     windows = []
+
     def __init__(self, item):
         Exporter.__init__(self, item)
         
@@ -55,58 +57,70 @@ class MatplotlibExporter(Exporter):
                 ax.xaxis.set_ticks_position('bottom')
     
     def export(self, fileName=None):
+        if not isinstance(self.item, PlotItem):
+            raise Exception("MatplotlibExporter currently only works with PlotItem")
+    
+        mpw = MatplotlibWindow()
+        MatplotlibExporter.windows.append(mpw)
+
+        fig = mpw.getFigure()
+
+        xax = self.item.getAxis('bottom')
+        yax = self.item.getAxis('left')
         
-        if isinstance(self.item, PlotItem):
+        # get labels from the graphic item
-            mpw = MatplotlibWindow()
+        xlabel = xax.label.toPlainText()
-            MatplotlibExporter.windows.append(mpw)
+        ylabel = yax.label.toPlainText()
+        title = self.item.titleLabel.text
 
-            stdFont = 'Arial'
+        # if axes use autoSIPrefix, scale the data so mpl doesn't add its own
-            
+        # scale factor label
-            fig = mpw.getFigure()
+        xscale = yscale = 1.0
-            
+        if xax.autoSIPrefix:
-            # get labels from the graphic item
+            xscale = xax.autoSIPrefixScale
-            xlabel = self.item.axes['bottom']['item'].label.toPlainText()
+        if yax.autoSIPrefix:
-            ylabel = self.item.axes['left']['item'].label.toPlainText()
+            yscale = yax.autoSIPrefixScale
-            title = self.item.titleLabel.text
 
-            ax = fig.add_subplot(111, title=title)
+        ax = fig.add_subplot(111, title=title)
-            ax.clear()
+        ax.clear()
-            self.cleanAxes(ax)
+        self.cleanAxes(ax)
-            #ax.grid(True)
+        for item in self.item.curves:
-            for item in self.item.curves:
+            x, y = item.getData()
-                x, y = item.getData()
+            x = x * xscale
-                opts = item.opts
+            y = y * yscale
-                pen = fn.mkPen(opts['pen'])
+
-                if pen.style() == QtCore.Qt.NoPen:
+            opts = item.opts
-                    linestyle = ''
+            pen = fn.mkPen(opts['pen'])
-                else:
+            if pen.style() == QtCore.Qt.NoPen:
-                    linestyle = '-'
+                linestyle = ''
-                color = tuple([c/255. for c in fn.colorTuple(pen.color())])
+            else:
-                symbol = opts['symbol']
+                linestyle = '-'
-                if symbol == 't':
+            color = tuple([c/255. for c in fn.colorTuple(pen.color())])
-                    symbol = '^'
+            symbol = opts['symbol']
-                symbolPen = fn.mkPen(opts['symbolPen'])
+            if symbol == 't':
-                symbolBrush = fn.mkBrush(opts['symbolBrush'])
+                symbol = '^'
-                markeredgecolor = tuple([c/255. for c in fn.colorTuple(symbolPen.color())])
+            symbolPen = fn.mkPen(opts['symbolPen'])
-                markerfacecolor = tuple([c/255. for c in fn.colorTuple(symbolBrush.color())])
+            symbolBrush = fn.mkBrush(opts['symbolBrush'])
-                markersize = opts['symbolSize']
+            markeredgecolor = tuple([c/255. for c in fn.colorTuple(symbolPen.color())])
-                
+            markerfacecolor = tuple([c/255. for c in fn.colorTuple(symbolBrush.color())])
-                if opts['fillLevel'] is not None and opts['fillBrush'] is not None:
+            markersize = opts['symbolSize']
-                    fillBrush = fn.mkBrush(opts['fillBrush'])
+            
-                    fillcolor = tuple([c/255. for c in fn.colorTuple(fillBrush.color())])
+            if opts['fillLevel'] is not None and opts['fillBrush'] is not None:
-                    ax.fill_between(x=x, y1=y, y2=opts['fillLevel'], facecolor=fillcolor)
+                fillBrush = fn.mkBrush(opts['fillBrush'])
-                
+                fillcolor = tuple([c/255. for c in fn.colorTuple(fillBrush.color())])
-                pl = ax.plot(x, y, marker=symbol, color=color, linewidth=pen.width(), 
+                ax.fill_between(x=x, y1=y, y2=opts['fillLevel'], facecolor=fillcolor)
-                        linestyle=linestyle, markeredgecolor=markeredgecolor, markerfacecolor=markerfacecolor,
+            
-                        markersize=markersize)
+            pl = ax.plot(x, y, marker=symbol, color=color, linewidth=pen.width(), 
-                xr, yr = self.item.viewRange()
+                    linestyle=linestyle, markeredgecolor=markeredgecolor, markerfacecolor=markerfacecolor,
-                ax.set_xbound(*xr)
+                    markersize=markersize)
-                ax.set_ybound(*yr)
+
-            ax.set_xlabel(xlabel)  # place the labels.
+            xr, yr = self.item.viewRange()
-            ax.set_ylabel(ylabel)
+            ax.set_xbound(xr[0]*xscale, xr[1]*xscale)
-            mpw.draw()
+            ax.set_ybound(yr[0]*yscale, yr[1]*yscale)
-        else:
+
-            raise Exception("Matplotlib export currently only works with plot items")
+        ax.set_xlabel(xlabel)  # place the labels.
+        ax.set_ylabel(ylabel)
+        mpw.draw()
                 
 MatplotlibExporter.register()        
         

pyqtgraph/exporters/tests/test_matplotlib.py

@@ -0,0 +1,50 @@
+# -*- coding: utf-8 -*-
+import pytest
+import pyqtgraph as pg
+from pyqtgraph.exporters import MatplotlibExporter
+pytest.importorskip("matplotlib")
+
+app = pg.mkQApp()
+
+
+def test_MatplotlibExporter():
+    plt = pg.plot()
+
+    # curve item
+    plt.plot([0, 1, 2], [0, 1, 2])
+    # scatter item
+    plt.plot([0, 1, 2], [1, 2, 3], pen=None, symbolBrush='r')
+    # curve + scatter
+    plt.plot([0, 1, 2], [2, 3, 4], pen='k', symbolBrush='r')
+
+    exp = MatplotlibExporter(plt.getPlotItem())
+    exp.export()
+
+
+def test_MatplotlibExporter_nonplotitem():
+    # attempting to export something other than a PlotItem raises an exception
+    plt = pg.plot()
+    plt.plot([0, 1, 2], [2, 3, 4])
+    exp = MatplotlibExporter(plt.getPlotItem().getViewBox())
+    with pytest.raises(Exception):
+        exp.export()
+
+
+@pytest.mark.parametrize('scale', [1e10, 1e-9])
+def test_MatplotlibExporter_siscale(scale):
+    # coarse test to verify that plot data is scaled before export when
+    # autoSIPrefix is in effect (so mpl doesn't add its own multiplier label)
+    plt = pg.plot([0, 1, 2], [(i+1)*scale for i in range(3)])
+    # set the label so autoSIPrefix works
+    plt.setLabel('left', 'magnitude')
+    exp = MatplotlibExporter(plt.getPlotItem())
+    exp.export()
+
+    mpw = MatplotlibExporter.windows[-1]
+    fig = mpw.getFigure()
+    ymin, ymax = fig.axes[0].get_ylim()
+
+    if scale < 1:
+        assert ymax > scale
+    else:
+        assert ymax < scale