feat: Improve the syntax for conditions with multiple predicates

altair/__init__.py

@@ -1,13 +1,6 @@
 # ruff: noqa
 __version__ = "5.4.0dev"
 
-from typing import Any
-
-# Necessary as mypy would see expr as the module alt.expr although due to how
-# the imports are set up it is expr in the alt.expr module
-expr: Any
-
-
 # The content of __all__ is automatically written by
 # tools/update_init_file.py. Do not modify directly.
 __all__ = [
@@ -54,6 +47,7 @@
     "BrushConfig",
     "CalculateTransform",
     "Categorical",
+    "ChainedWhen",
     "Chart",
     "ChartDataType",
     "ChartType",
@@ -488,6 +482,7 @@
     "TextDef",
     "TextDirection",
     "TextValue",
+    "Then",
     "Theta",
     "Theta2",
     "Theta2Datum",
@@ -565,6 +560,7 @@
     "VegaLiteSchema",
     "ViewBackground",
     "ViewConfig",
+    "When",
     "WindowEventType",
     "WindowFieldDef",
     "WindowOnlyOp",
@@ -622,7 +618,6 @@
     "load_ipython_extension",
     "load_schema",
     "mixins",
-    "overload",
     "param",
     "parse_shorthand",
     "renderers",
@@ -645,6 +640,7 @@
     "vconcat",
     "vegalite",
     "vegalite_compilers",
+    "when",
     "with_property_setters",
 ]
 
@@ -654,7 +650,9 @@ def __dir__():
 
 
 from altair.vegalite import *
+from altair.vegalite.v5.schema.core import Dict
 from altair.jupyter import JupyterChart
+from altair.expr import expr
 from altair.utils import AltairDeprecationWarning
 
 

altair/utils/__init__.py

@@ -8,6 +8,7 @@
     update_nested,
     display_traceback,
     SchemaBase,
+    SHORTHAND_KEYS,
 )
 from .html import spec_to_html
 from .plugin_registry import PluginRegistry
@@ -16,6 +17,7 @@
 
 
 __all__ = (
+    "SHORTHAND_KEYS",
     "AltairDeprecationWarning",
     "Optional",
     "PluginRegistry",

altair/utils/core.py

@@ -12,17 +12,7 @@
 import sys
 import traceback
 import warnings
-from typing import (
-    Callable,
-    TypeVar,
-    Any,
-    Iterator,
-    cast,
-    Literal,
-    Protocol,
-    TYPE_CHECKING,
-    runtime_checkable,
-)
+from typing import Callable, TypeVar, Any, Iterator, cast, Literal, TYPE_CHECKING
 from itertools import groupby
 from operator import itemgetter
 
@@ -33,6 +23,10 @@
 
 from altair.utils.schemapi import SchemaBase, Undefined
 
+if sys.version_info >= (3, 12):
+    from typing import runtime_checkable, Protocol
+else:
+    from typing_extensions import runtime_checkable, Protocol
 if sys.version_info >= (3, 10):
     from typing import ParamSpec
 else:
@@ -199,6 +193,22 @@ def __dataframe__(
     "utcsecondsmilliseconds",
 ]
 
+VALID_TYPECODES = list(itertools.chain(iter(TYPECODE_MAP), iter(INV_TYPECODE_MAP)))
+
+SHORTHAND_UNITS = {
+    "field": "(?P<field>.*)",
+    "type": "(?P<type>{})".format("|".join(VALID_TYPECODES)),
+    "agg_count": "(?P<aggregate>count)",
+    "op_count": "(?P<op>count)",
+    "aggregate": "(?P<aggregate>{})".format("|".join(AGGREGATES)),
+    "window_op": "(?P<op>{})".format("|".join(AGGREGATES + WINDOW_AGGREGATES)),
+    "timeUnit": "(?P<timeUnit>{})".format("|".join(TIMEUNITS)),
+}
+
+SHORTHAND_KEYS: frozenset[Literal["field", "aggregate", "type", "timeUnit"]] = (
+    frozenset(("field", "aggregate", "type", "timeUnit"))
+)
+
 
 def infer_vegalite_type_for_pandas(
     data: object,
@@ -577,18 +587,6 @@ def parse_shorthand(
     if not shorthand:
         return {}
 
-    valid_typecodes = list(TYPECODE_MAP) + list(INV_TYPECODE_MAP)
-
-    units = {
-        "field": "(?P<field>.*)",
-        "type": "(?P<type>{})".format("|".join(valid_typecodes)),
-        "agg_count": "(?P<aggregate>count)",
-        "op_count": "(?P<op>count)",
-        "aggregate": "(?P<aggregate>{})".format("|".join(AGGREGATES)),
-        "window_op": "(?P<op>{})".format("|".join(AGGREGATES + WINDOW_AGGREGATES)),
-        "timeUnit": "(?P<timeUnit>{})".format("|".join(TIMEUNITS)),
-    }
-
     patterns = []
 
     if parse_aggregates:
@@ -606,7 +604,8 @@ def parse_shorthand(
         patterns = list(itertools.chain(*((p + ":{type}", p) for p in patterns)))
 
     regexps = (
-        re.compile(r"\A" + p.format(**units) + r"\Z", re.DOTALL) for p in patterns
+        re.compile(r"\A" + p.format(**SHORTHAND_UNITS) + r"\Z", re.DOTALL)
+        for p in patterns
     )
 
     # find matches depending on valid fields passed