Added widgets to represent param.DateRange.

doc/AdditionalFeatures.ipynb

@@ -36,9 +36,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {
-    "collapsed": true
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "paramnb.Widgets(TooltipExample)"
@@ -75,9 +73,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {
-    "collapsed": true
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "paramnb.Widgets(Task)"
@@ -86,9 +82,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {
-    "collapsed": true
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "Task.employee.location.duration"
@@ -125,9 +119,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {
-    "collapsed": true
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "class HTMLExample(param.Parameterized):\n",
@@ -155,9 +147,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {
-    "collapsed": true
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "import holoviews as hv\n",
@@ -186,14 +176,90 @@
     "paramnb.Widgets(example, callback=example.update, on_init=True, view_position='right')"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {
+    "collapsed": true
+   },
+   "source": [
+    "# Date ranges\n",
+    "\n",
+    "param contains a DateRange parameter, consisting of start and end dates. However, it is often useful to allow users to specify dates in a variety of ways, so paramNB provides a DateRangeSelector widget with multiple possible date entry styles."
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
     "collapsed": true
    },
    "outputs": [],
-   "source": []
+   "source": [
+    "import datetime as dt"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": [
+    "class Test(param.Parameterized):\n",
+    "    date_range = param.DateRange(default=(dt.datetime(2017, 1, 1,),dt.datetime(2017, 12, 31)),\n",
+    "                           bounds=(dt.datetime(2016, 1, 1),dt.datetime(2018, 12, 31)))\n",
+    "\n",
+    "test = Test(name=\"An example class\")"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## start, end date"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "paramnb.Widgets(test) # default, \"StartEndDate\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## duration from start date"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "paramnb.Widgets(test,date_range_style='DurationFromStart')"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## duration to end date"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "paramnb.Widgets(test,date_range_style='DurationToEnd')"
+   ]
   }
  ],
  "metadata": {

paramnb/__init__.py

@@ -131,6 +131,12 @@ class Widgets(param.ParameterizedFunction):
         If true, will continuously update the next_n and/or callback, 
         if any, as a slider widget is dragged.""")
 
+    # passed through to DateRangeSelector widget
+    date_range_style = param.ObjectSelector(
+        default='StartEnd',
+        objects=['StartEnd','DurationFromStart','DurationToEnd'],doc="""
+        How to represent DateRange parameters; see widgets.DateRangeSelector.""")
+
     def __call__(self, parameterized, **params):
         self.p = param.ParamOverrides(self, params)
         if self.p.initializer:
@@ -209,6 +215,9 @@ def action_cb(button):
                 getattr(self.parameterized, p_name)(self.parameterized)
             kw['value'] = action_cb
 
+        if isinstance(p_obj,param.DateRange):
+            kw['date_range_style'] = self.p.date_range_style
+
         kw['name'] = p_name
 
         kw['continuous_update']=self.p.continuous_update

paramnb/widgets.py

@@ -1,4 +1,5 @@
 import re
+import datetime
 
 import param
 from param.parameterized import classlist
@@ -298,7 +299,154 @@ def _ipython_display_(self, **kwargs):
     def get_state(self, *args, **kw):
         # support layouts; see CrossSelect.get_state
         return self._composite.get_state(*args,**kw)
+
+
+class _DateRange(ipywidgets.Widget):
+    """
+    Abstract base class for composite widgets that use two widgets to
+    represent a (start, end) date range parameter.
+    """
+    __abstract = True
+
+    # TODO: could be tuple; need to decide about value of None
+    value = traitlets.Any()
+
+    def __init__(self, *args, **kwargs):
+        self._mindate = kwargs.get('min') 
+        self._maxdate = kwargs.get('max')
+        self.value = kwargs.pop('value')
+        assert self.value is not None # for now; see https://github.com/ioam/paramnb/issues/50
+        #if self.value is None and self._mindate is not None and self._maxdate is not None:
+        #    self.value = (self._mindate,self._maxdate)
+        self._w0 = self._create0(*args,**kwargs)
+        self._w1 = self._create1(*args,**kwargs)
+        self._composite = ipywidgets.VBox([self._w0,self._w1])
+        super(_DateRange, self).__init__()
+        self.layout = self._composite.layout
+        self._w0.observe(self._set0,'value')
+        self._w1.observe(self._set1,'value')
+
+    def _create0(self,*args,**kw):
+        raise NotImplementedError
+
+    def _create1(self,*args,**kw):
+        raise NotImplementedError
+
+    def _set0(self,e):
+        raise NotImplementedError
+
+    def _set1(self,e):
+        raise NotImplementedError
+
+    def _ipython_display_(self, **kwargs):
+        self._composite._ipython_display_(**kwargs)
+
+    def get_state(self, *args, **kw):
+        return self._composite.get_state(*args,**kw)
+
+
+class StartEnd(_DateRange):
+    """
+    Represents a DateRange parameter with start and end date pickers.
+    """
+    def _create0(self,*args,**kwargs):
+        kw = {'value':self.value[0],'description':'start'}
+        kw.update(kwargs)
+        return ipywidgets.DatePicker(*args,**kw)
+
+    def _create1(self,*args,**kwargs):
+        kw = {'value':self.value[1],'description':'end'}
+        kw.update(kwargs)
+        return ipywidgets.DatePicker(*args,**kw)
+
+    def _set0(self,e):
+        self.value = (e['new'],self.value[1])
+
+    def _set1(self,e):
+        self.value = (self.value[0],e['new'])
+
+
+class DurationToEnd(_DateRange):
+    """
+    Represents a DateRange parameter with end date picker plus
+    duration-to-end-date slider (or text widget if unbounded).
+
+    Duration is in days.
+    """
+    def _create0(self,*args,**kwargs):
+        kw = {'value':(self.value[1]-self.value[0]).days,
+              'description':'duration (days)'}
+        kw.update(kwargs)
+        if kw.get('max') is not None:
+            kw['max'] = (self.value[1]-kw['min']).days
+            kw['min'] = 0
+            return ipywidgets.IntSlider(*args,**kw)
+        else:
+            return TextWidget(*args,**kw)
+
+    def _create1(self,*args,**kwargs):
+        kw = {'value':self.value[1],'description':'end'}
+        kw.update(kwargs)
+        return ipywidgets.DatePicker(*args,**kw)
+
+    def _set0(self,e):
+        self.value = (self.value[1]-datetime.timedelta(int(e['new'])),self.value[1])
+
+    def _set1(self,e):
+        self.value = (self.value[0],e['new'])
+        if self._maxdate is not None:
+            self._w0.max = (self._maxdate-self.value[0]).days
+
+
+class DurationFromStart(_DateRange):
+    """
+    Represents a DateRange parameter with start date picker plus
+    duration-from-start-date slider (or text widget if unbounded).
+
+    Duration is in days.
+    """            
+    def _create0(self,*args,**kwargs):
+        kw = {'value':self.value[0],'description':'start'}
+        kw.update(kwargs)
+        return ipywidgets.DatePicker(*args,**kw)
+
+    def _create1(self,*args,**kwargs):
+        kw = {'value':(self.value[1]-self.value[0]).days,
+              'description':'duration (days)'}
+        kw.update(kwargs)
+        if kw.get('max') is not None:
+            kw['max'] = (kw['max']-self.value[0]).days
+            kw['min'] = 0
+            return ipywidgets.IntSlider(*args,**kw)
+        else:
+            return TextWidget(*args,**kw)
 
+    def _set0(self,e):
+        self.value = (e['new'],self.value[1])
+        if self._maxdate is not None:
+            self._w1.max = (self._maxdate - self.value[0]).days
+
+    def _set1(self,e):
+        self.value = (self.value[0],self.value[0]+datetime.timedelta(int(e['new'])))
+
+
+class DateRangeSelector(param.ParameterizedFunction):
+    """
+    Returns a _DateRange widget as specified by style parameter.
+    """
+    style = param.ClassSelector(_DateRange,default=StartEnd,is_instance=False,doc="""
+        Something.""")
+
+    def __call__(self, *args, **kw):
+        """
+        If date_range_style keyword argument is supplied, will be used to
+        set style and should be name of a _DateRange class.
+        """
+        date_range_style = kw.pop('date_range_style')
+        if date_range_style is not None:
+            self.style = self.params('style').get_range()[date_range_style]            
+        return self.style(*args, **kw)
+
 
 
 HTMLVIEW_JS = """
@@ -349,6 +497,9 @@ def apply_error_style(w, error):
     ImageView:           Image
 }
 
+# TODO: param/widget registry should specify all ideal mappings then
+# we should auto add whatever's available
+
 # Handle new parameters introduced in param 1.5
 try:
     from param import Color, Range
@@ -368,6 +519,12 @@ def apply_error_style(w, error):
 except:
     pass
 
+# Handle new parameters introduced in unreleased param
+try:
+    from param import DateRange
+    ptype2wtype[DateRange] = DateRangeSelector
+except:
+    pass
 
 def wtype(pobj):
     if pobj.constant: # Ensure constant parameters cannot be edited