Add num and round parameters to FloatLogSlider and FloatRangeSlider

Author: davidbrochart

docs/source/examples/Widget List.ipynb

@@ -85,7 +85,7 @@
    },
    "source": [
     "### FloatSlider\n",
-    "- In addition to the `step` parameter, a `FloatSlider` also accepts a `num` parameter, which specifies the number of values in the `[min, max]` interval. `num` takes precedence over `step`, and ensures that the `max` value is always included (which might not be the case due to floating point precision issues if the `step` parameter is used).\n",
+    "- In addition to the `step` parameter, float sliders (`FloatSlider`, `FloatLogSlider` and `FloatRangeSlider`) also accept a `num` parameter, which specifies the number of values in the `[min, max]` interval. `num` takes precedence over `step`, and ensures that the `max` value is always included (which might not be the case due to floating point precision issues if the `step` parameter is used).\n",
     "- A `round` parameter allows to round values that are set from the Python side to the closest value in the set of possible values. If `round` is `True`, values will be silently rounded (default value is `False`)."
    ]
   },

ipywidgets/widgets/widget_float.py

@@ -155,7 +155,7 @@ class FloatSlider(_BoundedFloat):
         step of the trackbar
     num : integer
         number of values in the [min, max] interval, takes precedence over
-        the step parameter.
+        the step parameter
     round : bool
         default is False, round the value set from Python to the closest value
         in the interval
@@ -229,6 +229,12 @@ class FloatLogSlider(_BoundedLogFloat):
         maximal position of the slider in log scale, i.e., actual maximum is base ** max
     step : float
         step of the trackbar, denotes steps for the exponent, not the actual value
+    num : integer
+        number of values in the [min, max] interval, takes precedence over
+        the step parameter
+    round : bool
+        default is False, round the value set from Python to the closest value
+        in the interval
     description : str
         name of the slider
     orientation : {'horizontal', 'vertical'}
@@ -243,6 +249,8 @@ class FloatLogSlider(_BoundedLogFloat):
     _view_name = Unicode('FloatLogSliderView').tag(sync=True)
     _model_name = Unicode('FloatLogSliderModel').tag(sync=True)
     step = CFloat(0.1, allow_none=True, help="Minimum step in the exponent to increment the value").tag(sync=True)
+    num = CInt(help="Number of values in the [min, max] interval").tag(sync=True)
+    round = Bool(False, help="Round the value set from Python to the closest value in the interval").tag(sync=True)
     orientation = CaselessStrEnum(values=['horizontal', 'vertical'],
         default_value='horizontal', help="Vertical or horizontal.").tag(sync=True)
     readout = Bool(True, help="Display the current value of the slider next to it.").tag(sync=True)
@@ -254,6 +262,33 @@ class FloatLogSlider(_BoundedLogFloat):
 
     style = InstanceDict(SliderStyle).tag(sync=True, **widget_serialization)
 
+    @validate('value')
+    def _validate_value(self, proposal):
+        value = proposal['value']
+        if not self.round:
+            return value
+        # round value to closest one in interval
+        values = [self.min]
+        while values[-1] <= self.max:
+            values.append(values[-1] + self.step)
+        rounded_value = min(values, key=lambda x:abs(x-value))
+        return rounded_value
+
+    @validate('num')
+    def _validate_num(self, proposal):
+        # step value is computed from num
+        # num is not used in the front-end
+        num = proposal['value']
+        if self.min == self.max:
+            if num != 1:
+                raise TraitError('num must be 1 because min == max')
+            self.step = 0
+        elif num <= 1:
+            raise TraitError('num must be greater than 1')
+        else:
+            self.step = (self.max - self.min) / (num - 1)
+        return num
+
 
 @register
 class FloatProgress(_BoundedFloat):
@@ -374,7 +409,9 @@ class FloatRangeSlider(_BoundedFloatRange):
         step of the trackbar
     num : integer
         number of values in the [min, max] interval, takes precedence over
-        the step parameter.
+        the step parameter
+    round : bool
+        default is False, round the value set from Python to the closest value
     description : str
         name of the slider
     orientation : {'horizontal', 'vertical'}
@@ -390,6 +427,7 @@ class FloatRangeSlider(_BoundedFloatRange):
     _model_name = Unicode('FloatRangeSliderModel').tag(sync=True)
     step = CFloat(0.1, allow_none=True, help="Minimum step to increment the value").tag(sync=True)
     num = CInt(help="Number of values in the [min, max] interval").tag(sync=True)
+    round = Bool(False, help="Round the value set from Python to the closest value in the interval").tag(sync=True)
     orientation = CaselessStrEnum(values=['horizontal', 'vertical'],
         default_value='horizontal', help="Vertical or horizontal.").tag(sync=True)
     readout = Bool(True, help="Display the current value of the slider next to it.").tag(sync=True)
@@ -400,6 +438,18 @@ class FloatRangeSlider(_BoundedFloatRange):
 
     style = InstanceDict(SliderStyle).tag(sync=True, **widget_serialization)
 
+    @validate('value')
+    def _validate_value(self, proposal):
+        value = proposal['value']
+        if not self.round:
+            return value
+        # round value to closest one in interval
+        values = [self.min]
+        while values[-1] <= self.max:
+            values.append(values[-1] + self.step)
+        rounded_value = min(values, key=lambda x:abs(x-value))
+        return rounded_value
+
     @validate('num')
     def _validate_num(self, proposal):
         # step value is computed from num

packages/schema/jupyterwidgetmodels.latest.md

@@ -461,9 +461,11 @@ Attribute        | Type             | Default          | Help
 `layout`         | reference to Layout widget | reference to new instance | 
 `max`            | number (float)   | `4.0`            | Max value for the exponent
 `min`            | number (float)   | `0.0`            | Min value for the exponent
+`num`            | number (integer) | `0`              | Number of values in the [min, max] interval
 `orientation`    | string (one of `'horizontal'`, `'vertical'`) | `'horizontal'`   | Vertical or horizontal.
 `readout`        | boolean          | `true`           | Display the current value of the slider next to it.
 `readout_format` | string           | `'.3g'`          | Format for the readout
+`round`          | boolean          | `false`          | Round the value set from Python to the closest value in the interval
 `step`           | `null` or number (float) | `0.1`            | Minimum step in the exponent to increment the value
 `style`          | reference to SliderStyle widget | reference to new instance | 
 `tabbable`       | `null` or boolean | `null`           | Is widget tabbable?
@@ -513,6 +515,7 @@ Attribute        | Type             | Default          | Help
 `orientation`    | string (one of `'horizontal'`, `'vertical'`) | `'horizontal'`   | Vertical or horizontal.
 `readout`        | boolean          | `true`           | Display the current value of the slider next to it.
 `readout_format` | string           | `'.2f'`          | Format for the readout
+`round`          | boolean          | `false`          | Round the value set from Python to the closest value in the interval
 `step`           | `null` or number (float) | `0.1`            | Minimum step to increment the value
 `style`          | reference to SliderStyle widget | reference to new instance | 
 `tabbable`       | `null` or boolean | `null`           | Is widget tabbable?