WIP: update to Vega-Lite 5.2

.github/workflows/build.yml

@@ -25,6 +25,7 @@ jobs:
         python -m pip install --upgrade pip
         pip install .[dev]
         pip install altair_saver
+        pip install git+git://github.com/altair-viz/altair_viewer.git
     - name: Test with pytest
       run: |
         pytest --doctest-modules altair

.github/workflows/docbuild.yml

@@ -21,6 +21,7 @@ jobs:
         pip install .[dev]
         pip install altair_saver
         pip install -r doc/requirements.txt
+        pip install git+git://github.com/altair-viz/altair_viewer.git
     - name: Run docbuild
       run: |
         cd doc && make ${{ matrix.build-type }}

altair/examples/grouped_bar_chart2.py

@@ -0,0 +1,20 @@
+"""
+Grouped Bar Chart with xOffset
+------------------------------
+Like :ref:`gallery_grouped_bar_chart`, this example shows a grouped bar chart.  Whereas :ref:`gallery_grouped_bar_chart` used the ``column`` encoding channel, this example uses the ``xOffset`` encoding channel.  This is adapted from a corresponding Vega-Lite Example:
+`Grouped Bar Chart <https://vega.github.io/vega-lite/examples/bar_grouped.html>`_.
+"""
+# category: bar charts
+import altair as alt
+import pandas as pd
+
+source = pd.DataFrame({"Category":list("AAABBBCCC"),
+                     "Group":list("xyzxyzxyz"),
+                     "Value":[0.1, 0.6, 0.9, 0.7, 0.2, 1.1, 0.6, 0.1, 0.2]})
+
+alt.Chart(source).mark_bar().encode(
+    x="Category:N",
+    y="Value:Q",
+    xOffset="Group:N",
+    color="Group:N"
+)

altair/examples/jitter_chart.py

@@ -0,0 +1,21 @@
+"""
+Jitter Chart
+------------
+In this chart, we encode the ``Cylinders`` column from the ``cars`` dataset in the ``y``-channel.  Because most cars (all but seven) in this dataset have 4, 6, or 8 cylinders, the default presentation of this data would show most of the data concentrated on three horizontal lines.  Furthermore, in that default presentation, it would be difficult to gauge the relative frequencies with which different values occur (because there would be so much overlap).  To compensate for this, we use the ``yOffset`` channel to incorporate a random offset (jittering).  This is adapted from a corresponding Vega-Lite Example:
+`Dot Plot with Jittering <https://vega.github.io/vega-lite/examples/point_offset_random.html>`_.
+"""
+# category: scatter plots
+import altair as alt
+from vega_datasets import data
+
+source = data.cars()
+
+alt.Chart(source).mark_point().encode(
+    x='Horsepower:Q',
+    y='Cylinders:O',
+    yOffset='randomCalc:Q'
+).transform_calculate(
+    randomCalc='random()'
+).properties(
+    height=alt.Step(50)
+)

altair/examples/scatter_with_minimap.py

@@ -35,11 +35,11 @@
     .mark_point()
     .encode(
         x=alt.X(
-            "date:T", scale=alt.Scale(domain={"selection": zoom.name, "encoding": "x"})
+            "date:T", scale=alt.Scale(domain={"param": zoom.name, "encoding": "x"})
         ),
         y=alt.Y(
             "temp_max:Q",
-            scale=alt.Scale(domain={"selection": zoom.name, "encoding": "y"}),
+            scale=alt.Scale(domain={"param": zoom.name, "encoding": "y"}),
         ),
         color="weather",
     )

altair/examples/slider_cutoff.py

@@ -0,0 +1,30 @@
+"""
+Slider Cutoff
+=============
+This example shows how to bind a variable parameter to a slider, and how to use the corresponding bound value to color data points.  This example is based on an example from the Altair 4 documentation for Interactions, in which the  interactivity was accomplished using a selection.  The version below has been simplified significantly through the use of a variable parameter.  Variable parameters were added in Altair 5.
+"""
+# category: interactive charts
+import altair as alt
+import pandas as pd
+import numpy as np
+
+rand = np.random.RandomState(42)
+
+df = pd.DataFrame({
+    'xval': range(100),
+    'yval': rand.randn(100).cumsum()
+})
+
+slider = alt.binding_range(min=0, max=100, step=1)
+cutoff = alt.parameter(bind=slider, value=50)
+
+alt.Chart(df).mark_point().encode(
+    x='xval',
+    y='yval',
+    color=alt.condition(
+        alt.datum.xval < cutoff,
+        alt.value('red'), alt.value('blue')
+    )
+).add_parameter(
+    cutoff
+)

altair/expr/core.py

@@ -31,114 +31,151 @@ def _js_repr(val):
         return "false"
     elif val is None:
         return "null"
+    elif isinstance(val, OperatorMixin):
+        return val._to_expr()
     else:
         return repr(val)
 
 
-class Expression(SchemaBase):
-    """Expression
-
-    Base object for enabling build-up of Javascript expressions using
-    a Python syntax. Calling ``repr(obj)`` will return a Javascript
-    representation of the object and the operations it encodes.
-    """
-
-    _schema = {"type": "string"}
-
-    def to_dict(self, *args, **kwargs):
+# Designed to work with Expression and VariableParameter
+class OperatorMixin(object):
+    def _to_expr(self):
         return repr(self)
 
-    def __setattr__(self, attr, val):
-        # We don't need the setattr magic defined in SchemaBase
-        return object.__setattr__(self, attr, val)
+    def _from_expr(self, expr):
+        return expr
 
     def __add__(self, other):
-        return BinaryExpression("+", self, other)
+        comp_value = BinaryExpression("+", self, other)
+        return self._from_expr(comp_value)
 
     def __radd__(self, other):
-        return BinaryExpression("+", other, self)
+        comp_value = BinaryExpression("+", other, self)
+        return self._from_expr(comp_value)
 
     def __sub__(self, other):
-        return BinaryExpression("-", self, other)
+        comp_value = BinaryExpression("-", self, other)
+        return self._from_expr(comp_value)
 
     def __rsub__(self, other):
-        return BinaryExpression("-", other, self)
+        comp_value = BinaryExpression("-", other, self)
+        return self._from_expr(comp_value)
 
     def __mul__(self, other):
-        return BinaryExpression("*", self, other)
+        comp_value = BinaryExpression("*", self, other)
+        return self._from_expr(comp_value)
 
     def __rmul__(self, other):
-        return BinaryExpression("*", other, self)
+        comp_value = BinaryExpression("*", other, self)
+        return self._from_expr(comp_value)
 
     def __truediv__(self, other):
-        return BinaryExpression("/", self, other)
+        comp_value = BinaryExpression("/", self, other)
+        return self._from_expr(comp_value)
 
     def __rtruediv__(self, other):
-        return BinaryExpression("/", other, self)
+        comp_value = BinaryExpression("/", other, self)
+        return self._from_expr(comp_value)
 
     __div__ = __truediv__
 
     __rdiv__ = __rtruediv__
 
     def __mod__(self, other):
-        return BinaryExpression("%", self, other)
+        comp_value = BinaryExpression("%", self, other)
+        return self._from_expr(comp_value)
 
     def __rmod__(self, other):
-        return BinaryExpression("%", other, self)
+        comp_value = BinaryExpression("%", other, self)
+        return self._from_expr(comp_value)
 
     def __pow__(self, other):
         # "**" Javascript operator is not supported in all browsers
-        return FunctionExpression("pow", (self, other))
+        comp_value = FunctionExpression("pow", (self, other))
+        return self._from_expr(comp_value)
 
     def __rpow__(self, other):
         # "**" Javascript operator is not supported in all browsers
-        return FunctionExpression("pow", (other, self))
+        comp_value = FunctionExpression("pow", (other, self))
+        return self._from_expr(comp_value)
 
     def __neg__(self):
-        return UnaryExpression("-", self)
+        comp_value = UnaryExpression("-", self)
+        return self._from_expr(comp_value)
 
     def __pos__(self):
-        return UnaryExpression("+", self)
+        comp_value = UnaryExpression("+", self)
+        return self._from_expr(comp_value)
 
     # comparison operators
 
     def __eq__(self, other):
-        return BinaryExpression("===", self, other)
+        comp_value = BinaryExpression("===", self, other)
+        return self._from_expr(comp_value)
 
     def __ne__(self, other):
-        return BinaryExpression("!==", self, other)
+        comp_value = BinaryExpression("!==", self, other)
+        return self._from_expr(comp_value)
 
     def __gt__(self, other):
-        return BinaryExpression(">", self, other)
+        comp_value = BinaryExpression(">", self, other)
+        return self._from_expr(comp_value)
 
     def __lt__(self, other):
-        return BinaryExpression("<", self, other)
+        comp_value = BinaryExpression("<", self, other)
+        return self._from_expr(comp_value)
 
     def __ge__(self, other):
-        return BinaryExpression(">=", self, other)
+        comp_value = BinaryExpression(">=", self, other)
+        return self._from_expr(comp_value)
 
     def __le__(self, other):
-        return BinaryExpression("<=", self, other)
+        comp_value = BinaryExpression("<=", self, other)
+        return self._from_expr(comp_value)
 
     def __abs__(self):
-        return FunctionExpression("abs", (self,))
+        comp_value = FunctionExpression("abs", (self,))
+        return self._from_expr(comp_value)
 
     # logical operators
 
     def __and__(self, other):
-        return BinaryExpression("&&", self, other)
+        comp_value = BinaryExpression("&&", self, other)
+        return self._from_expr(comp_value)
 
     def __rand__(self, other):
-        return BinaryExpression("&&", other, self)
+        comp_value = BinaryExpression("&&", other, self)
+        return self._from_expr(comp_value)
 
     def __or__(self, other):
-        return BinaryExpression("||", self, other)
+        comp_value = BinaryExpression("||", self, other)
+        return self._from_expr(comp_value)
 
     def __ror__(self, other):
-        return BinaryExpression("||", other, self)
+        comp_value = BinaryExpression("||", other, self)
+        return self._from_expr(comp_value)
 
     def __invert__(self):
-        return UnaryExpression("!", self)
+        comp_value = UnaryExpression("!", self)
+        return self._from_expr(comp_value)
+
+
+class Expression(OperatorMixin, SchemaBase):
+    """Expression
+
+    Base object for enabling build-up of Javascript expressions using
+    a Python syntax. Calling ``repr(obj)`` will return a Javascript
+    representation of the object and the operations it encodes.
+    """
+
+    _schema = {"type": "string"}
+
+    def to_dict(self, *args, **kwargs):
+        return repr(self)
+
+    def __setattr__(self, attr, val):
+        # We don't need the setattr magic defined in SchemaBase
+        return object.__setattr__(self, attr, val)
 
     # item access
     def __getitem__(self, val):

altair/utils/tests/test_mimebundle.py

@@ -15,7 +15,7 @@ def require_altair_saver():
 @pytest.fixture
 def vegalite_spec():
     return {
-        "$schema": "https://vega.github.io/schema/vega-lite/v4.json",
+        "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
         "description": "A simple bar chart with embedded data.",
         "data": {
             "values": [
@@ -97,10 +97,18 @@ def vega_spec():
                 "name": "data_0",
                 "source": "source_0",
                 "transform": [
+                    {
+                        "as": ["b_start", "b_end"],
+                        "field": "b",
+                        "groupby": ["a"],
+                        "offset": "zero",
+                        "sort": {"field": [], "order": []},
+                        "type": "stack",
+                    },
                     {
                         "expr": 'isValid(datum["b"]) && isFinite(+datum["b"])',
                         "type": "filter",
-                    }
+                    },
                 ],
             },
         ],
@@ -117,8 +125,8 @@ def vega_spec():
                         "fill": {"value": "#4c78a8"},
                         "width": {"band": 1, "scale": "x"},
                         "x": {"field": "a", "scale": "x"},
-                        "y": {"field": "b", "scale": "y"},
-                        "y2": {"scale": "y", "value": 0},
+                        "y": {"field": "b_end", "scale": "y"},
+                        "y2": {"field": "b_start", "scale": "y"},
                     }
                 },
                 "from": {"data": "data_0"},
@@ -138,7 +146,7 @@ def vega_spec():
                 "type": "band",
             },
             {
-                "domain": {"data": "data_0", "field": "b"},
+                "domain": {"data": "data_0", "fields": ["b_start", "b_end"]},
                 "name": "y",
                 "nice": True,
                 "range": [{"signal": "height"}, 0],
@@ -188,7 +196,7 @@ def test_spec_to_vegalite_mimebundle(vegalite_spec):
         format="vega-lite",
         vegalite_version=alt.VEGALITE_VERSION,
     )
-    assert bundle == {"application/vnd.vegalite.v4+json": vegalite_spec}
+    assert bundle == {"application/vnd.vegalite.v5+json": vegalite_spec}
 
 
 def test_spec_to_vega_mimebundle(vega_spec):

altair/utils/tests/test_plugin_registry.py

@@ -26,7 +26,7 @@ def test_plugin_registry():
     assert plugins.get() is None
     assert repr(plugins) == "TypedCallableRegistry(active='', registered=[])"
 
-    plugins.register("new_plugin", lambda x: x ** 2)
+    plugins.register("new_plugin", lambda x: x**2)
     assert plugins.names() == ["new_plugin"]
     assert plugins.active == ""
     assert plugins.get() is None
@@ -46,7 +46,7 @@ def test_plugin_registry():
 def test_plugin_registry_extra_options():
     plugins = GeneralCallableRegistry()
 
-    plugins.register("metadata_plugin", lambda x, p=2: x ** p)
+    plugins.register("metadata_plugin", lambda x, p=2: x**p)
     plugins.enable("metadata_plugin")
     assert plugins.get()(3) == 9
 
@@ -86,7 +86,7 @@ def test_plugin_registry_global_settings():
 def test_plugin_registry_context():
     plugins = GeneralCallableRegistry()
 
-    plugins.register("default", lambda x, p=2: x ** p)
+    plugins.register("default", lambda x, p=2: x**p)
 
     # At first there is no plugin enabled
     assert plugins.active == ""

altair/vegalite/__init__.py

@@ -1,2 +1,2 @@
 # flake8: noqa
-from .v4 import *
+from .v5 import *

altair/vegalite/schema.py

@@ -1,3 +1,3 @@
 """Altair schema wrappers"""
 # flake8: noqa
-from .v4.schema import *
+from .v5.schema import *