Date axis item

doc/source/graphicsItems/dateaxisitem.rst

@@ -0,0 +1,8 @@
+DateAxisItem
+============
+
+.. autoclass:: pyqtgraph.DateAxisItem
+    :members:
+
+    .. automethod:: pyqtgraph.DateAxisItem.__init__
+

doc/source/graphicsItems/index.rst

@@ -43,3 +43,4 @@ Contents:
     graphicsitem
     uigraphicsitem
     graphicswidgetanchor
+    dateaxisitem

doc/source/graphicsItems/make

@@ -2,6 +2,7 @@ files = """ArrowItem
 AxisItem
 ButtonItem
 CurvePoint
+DateAxisItem
 GradientEditorItem
 GradientLegend
 GraphicsLayout

examples/DateAxisItem.py

@@ -0,0 +1,33 @@
+"""
+Demonstrates the usage of DateAxisItem to display properly-formatted 
+timestamps on x-axis which automatically adapt to current zoom level.
+
+"""
+import initExample ## Add path to library (just for examples; you do not need this)
+
+import time
+from datetime import datetime, timedelta
+
+import numpy as np
+import pyqtgraph as pg
+from pyqtgraph.Qt import QtGui
+
+app = QtGui.QApplication([])
+
+# Create a plot with a date-time axis
+w = pg.PlotWidget(axisItems = {'bottom': pg.DateAxisItem()})
+w.showGrid(x=True, y=True)
+
+# Plot sin(1/x^2) with timestamps in the last 100 years
+now = time.time()
+x = np.linspace(2*np.pi, 1000*2*np.pi, 8301)
+w.plot(now-(2*np.pi/x)**2*100*np.pi*1e7, np.sin(x), symbol='o')
+
+w.setWindowTitle('pyqtgraph example: DateAxisItem')
+w.show()
+
+## Start Qt event loop unless running in interactive mode or using pyside.
+if __name__ == '__main__':
+    import sys
+    if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
+        app.exec_()

examples/DateAxisItem_QtDesigner.py

@@ -0,0 +1,48 @@
+"""
+Demonstrates the usage of DateAxisItem in a layout created with Qt Designer.
+
+The spotlight here is on the 'setAxisItems' method, without which
+one would have to subclass plotWidget in order to attach a dateaxis to it.
+
+"""
+import initExample ## Add path to library (just for examples; you do not need this)
+
+import sys
+import time
+
+import numpy as np
+from PyQt5 import QtWidgets, QtCore, uic
+import pyqtgraph as pg
+
+pg.setConfigOption('background', 'w')
+pg.setConfigOption('foreground', 'k')
+
+BLUE = pg.mkPen('#1f77b4')
+
+Design, _ = uic.loadUiType('DateAxisItem_QtDesigner.ui')
+
+class ExampleApp(QtWidgets.QMainWindow, Design):
+    def __init__(self):
+        super().__init__()
+        self.setupUi(self)
+        now = time.time()
+        # Plot random values with timestamps in the last 6 months
+        timestamps = np.linspace(now - 6*30*24*3600, now, 100)
+        self.curve = self.plotWidget.plot(x=timestamps, y=np.random.rand(100), 
+                                          symbol='o', symbolSize=5, pen=BLUE)
+        # 'o' circle  't' triangle  'd' diamond  '+' plus  's' square
+        self.plotWidget.setAxisItems({'bottom': pg.DateAxisItem()})
+        self.plotWidget.showGrid(x=True, y=True)
+
+app = QtWidgets.QApplication(sys.argv)
+app.setStyle(QtWidgets.QStyleFactory.create('Fusion'))
+app.setPalette(QtWidgets.QApplication.style().standardPalette())
+window = ExampleApp()
+window.setWindowTitle('pyqtgraph example: DateAxisItem_QtDesigner')
+window.show()
+
+## Start Qt event loop unless running in interactive mode or using pyside.
+if __name__ == '__main__':
+    import sys
+    if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
+        app.exec_()

examples/DateAxisItem_QtDesigner.ui

@@ -0,0 +1,44 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>MainWindow</class>
+ <widget class="QMainWindow" name="MainWindow">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>536</width>
+    <height>381</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>MainWindow</string>
+  </property>
+  <widget class="QWidget" name="centralwidget">
+   <layout class="QVBoxLayout" name="verticalLayout">
+    <item>
+     <widget class="PlotWidget" name="plotWidget"/>
+    </item>
+   </layout>
+  </widget>
+  <widget class="QMenuBar" name="menubar">
+   <property name="geometry">
+    <rect>
+     <x>0</x>
+     <y>0</y>
+     <width>536</width>
+     <height>18</height>
+    </rect>
+   </property>
+  </widget>
+  <widget class="QStatusBar" name="statusbar"/>
+ </widget>
+ <customwidgets>
+  <customwidget>
+   <class>PlotWidget</class>
+   <extends>QGraphicsView</extends>
+   <header>pyqtgraph</header>
+  </customwidget>
+ </customwidgets>
+ <resources/>
+ <connections/>
+</ui>

examples/customPlot.py

@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 """
-This example demonstrates the creation of a plot with a customized
-AxisItem and ViewBox. 
+This example demonstrates the creation of a plot with 
+DateAxisItem and a customized ViewBox. 
 """
 
 
@@ -12,40 +12,6 @@
 import numpy as np
 import time
 
-class DateAxis(pg.AxisItem):
-    def tickStrings(self, values, scale, spacing):
-        strns = []
-        rng = max(values)-min(values)
-        #if rng < 120:
-        #    return pg.AxisItem.tickStrings(self, values, scale, spacing)
-        if rng < 3600*24:
-            string = '%H:%M:%S'
-            label1 = '%b %d -'
-            label2 = ' %b %d, %Y'
-        elif rng >= 3600*24 and rng < 3600*24*30:
-            string = '%d'
-            label1 = '%b - '
-            label2 = '%b, %Y'
-        elif rng >= 3600*24*30 and rng < 3600*24*30*24:
-            string = '%b'
-            label1 = '%Y -'
-            label2 = ' %Y'
-        elif rng >=3600*24*30*24:
-            string = '%Y'
-            label1 = ''
-            label2 = ''
-        for x in values:
-            try:
-                strns.append(time.strftime(string, time.localtime(x)))
-            except ValueError:  ## Windows can't handle dates before 1970
-                strns.append('')
-        try:
-            label = time.strftime(label1, time.localtime(min(values)))+time.strftime(label2, time.localtime(max(values)))
-        except ValueError:
-            label = ''
-        #self.setLabel(text=label)
-        return strns
-
 class CustomViewBox(pg.ViewBox):
     def __init__(self, *args, **kwds):
         pg.ViewBox.__init__(self, *args, **kwds)
@@ -65,10 +31,10 @@ def mouseDragEvent(self, ev):
 
 app = pg.mkQApp()
 
-axis = DateAxis(orientation='bottom')
+axis = pg.DateAxisItem(orientation='bottom')
 vb = CustomViewBox()
 
-pw = pg.PlotWidget(viewBox=vb, axisItems={'bottom': axis}, enableMenu=False, title="PlotItem with custom axis and ViewBox<br>Menu disabled, mouse behavior changed: left-drag to zoom, right-click to reset zoom")
+pw = pg.PlotWidget(viewBox=vb, axisItems={'bottom': axis}, enableMenu=False, title="PlotItem with DateAxisItem and custom ViewBox<br>Menu disabled, mouse behavior changed: left-drag to zoom, right-click to reset zoom")
 dates = np.arange(8) * (3600*24*356)
 pw.plot(x=dates, y=[1,6,2,4,3,5,6,8], symbol='o')
 pw.show()

examples/utils.py

@@ -14,6 +14,7 @@
     ('Crosshair / Mouse interaction', 'crosshair.py'),
     ('Data Slicing', 'DataSlicing.py'),
     ('Plot Customization', 'customPlot.py'),
+    ('Timestamps on x axis', 'DateAxisItem.py'),
     ('Image Analysis', 'imageAnalysis.py'),
     ('ViewBox Features', 'ViewBoxFeatures.py'),
     ('Dock widgets', 'dockarea.py'),

pyqtgraph/__init__.py

@@ -219,6 +219,7 @@ def renamePyc(startDir):
 from .graphicsItems.ArrowItem import * 
 from .graphicsItems.ImageItem import * 
 from .graphicsItems.AxisItem import * 
+from .graphicsItems.DateAxisItem import *
 from .graphicsItems.LabelItem import * 
 from .graphicsItems.CurvePoint import * 
 from .graphicsItems.GraphicsWidgetAnchor import * 

pyqtgraph/graphicsItems/AxisItem.py

@@ -507,20 +507,29 @@ def linkedView(self):
 
     def linkToView(self, view):
         """Link this axis to a ViewBox, causing its displayed range to match the visible range of the view."""
-        oldView = self.linkedView()
+        self.unlinkFromView()
+
         self._linkedView = weakref.ref(view)
+        if self.orientation in ['right', 'left']:
+            view.sigYRangeChanged.connect(self.linkedViewChanged)
+        else:
+            view.sigXRangeChanged.connect(self.linkedViewChanged)
+
+        view.sigResized.connect(self.linkedViewChanged)
+
+    def unlinkFromView(self):
+        """Unlink this axis from a ViewBox."""
+        oldView = self.linkedView()
+        self._linkedView = None
         if self.orientation in ['right', 'left']:
             if oldView is not None:
                 oldView.sigYRangeChanged.disconnect(self.linkedViewChanged)
-            view.sigYRangeChanged.connect(self.linkedViewChanged)
         else:
             if oldView is not None:
                 oldView.sigXRangeChanged.disconnect(self.linkedViewChanged)
-            view.sigXRangeChanged.connect(self.linkedViewChanged)
 
         if oldView is not None:
             oldView.sigResized.disconnect(self.linkedViewChanged)
-        view.sigResized.connect(self.linkedViewChanged)
 
     def linkedViewChanged(self, view, newRange=None):
         if self.orientation in ['right', 'left']: