docs: Use when in arguments syntax examples (1/2)

Covers all the examples that had a *methods* equivalent.
Now have 16 more to do, across 12 files

tests/examples_arguments_syntax/interactive_column_selection.py

@@ -37,7 +37,7 @@
     alt.X('level_0', title=None),
     alt.Y('level_1', title=None),
     alt.Color('correlation', scale=alt.Scale(domain=[-1, 1], scheme='blueorange')),
-    opacity=alt.condition(select_x & select_y, alt.value(1), alt.value(0.4))
+    opacity=alt.when(select_x, select_y).then(alt.value(1)).otherwise(alt.value(0.4)),
 ).add_params(
     select_x, select_y
 )

tests/examples_arguments_syntax/interactive_cross_highlight.py

@@ -34,7 +34,7 @@
 bar = alt.Chart(source).mark_bar().encode(
     x='Major_Genre:N',
     y='count()',
-    color=alt.condition(pts, alt.ColorValue("steelblue"), alt.ColorValue("grey"))
+    color=alt.when(pts).then(alt.ColorValue("steelblue")).otherwise(alt.ColorValue("grey"))
 ).properties(
     width=550,
     height=200

tests/examples_arguments_syntax/interactive_legend.py

@@ -17,7 +17,7 @@
     alt.X('yearmonth(date):T', axis=alt.Axis(domain=False, format='%Y', tickSize=0)),
     alt.Y('sum(count):Q', stack='center', axis=None),
     alt.Color('series:N', scale=alt.Scale(scheme='category20b')),
-    opacity=alt.condition(selection, alt.value(1), alt.value(0.2))
+    opacity=alt.when(selection).then(alt.value(1)).otherwise(alt.value(0.2))
 ).add_params(
     selection
 )

tests/examples_arguments_syntax/interval_selection_map_quakes.py

@@ -38,7 +38,7 @@
 ).mark_circle(opacity=0.35, tooltip=True).encode(
     longitude="lon:Q",
     latitude="lat:Q",
-    color=alt.condition(brush, alt.value("goldenrod"), alt.value("steelblue")),
+    color=alt.when(brush).then(alt.value("goldenrod")).otherwise(alt.value("steelblue")),
     size=alt.Size("mag:Q", scale=alt.Scale(type="pow", range=[1, 1000], domain=[0, 7], exponent=4)),
 ).add_params(brush)
 

tests/examples_arguments_syntax/lasagna_plot.py

@@ -8,10 +8,10 @@
 
 source = data.stocks()
 
-color_condition = alt.condition(
-    "month(datum.value) == 1 && date(datum.value) == 1",
-    alt.value("black"),
-    alt.value(None),
+color_condition = (
+    alt.when(alt.expr.month("datum.value") == 1, alt.expr.date("datum.value") == 1)
+    .then(alt.value("black"))
+    .otherwise(alt.value(None))
 )
 
 alt.Chart(source, width=300, height=100).transform_filter(
@@ -23,8 +23,8 @@
             format="%Y",
             labelAngle=0,
             labelOverlap=False,
-            labelColor=color_condition,
-            tickColor=color_condition,
+            labelColor=color_condition, # type: ignore[arg-type]
+            tickColor=color_condition, # type: ignore[arg-type]
         ),
         title="Time",
     ),

tests/examples_arguments_syntax/layered_heatmap_text.py

@@ -28,14 +28,14 @@
     )
 )
 
+color = (
+    alt.when(alt.datum.mean_horsepower > 150)
+    .then(alt.value("black"))
+    .otherwise(alt.value("white"))
+)
 # Configure text
 text = base.mark_text(baseline='middle').encode(
-    text=alt.Text('mean_horsepower:Q', format=".0f"),
-    color=alt.condition(
-        alt.datum.mean_horsepower > 150,
-        alt.value('black'),
-        alt.value('white')
-    )
+    text=alt.Text('mean_horsepower:Q', format=".0f"), color=color
 )
 
 # Draw the chart

tests/examples_arguments_syntax/multiline_highlight.py

@@ -30,7 +30,7 @@
 )
 
 lines = base.mark_line().encode(
-    size=alt.condition(~highlight, alt.value(1), alt.value(3))
+    size=alt.when(~highlight).then(alt.value(1)).otherwise(alt.value(3))
 )
 
 points + lines

tests/examples_arguments_syntax/multiline_tooltip.py

@@ -41,15 +41,16 @@
 ).add_params(
     nearest
 )
+when_near = alt.when(nearest)
 
 # Draw points on the line, and highlight based on selection
 points = line.mark_point().encode(
-    opacity=alt.condition(nearest, alt.value(1), alt.value(0))
+    opacity=when_near.then(alt.value(1)).otherwise(alt.value(0))
 )
 
 # Draw text labels near the points, and highlight based on selection
 text = line.mark_text(align="left", dx=5, dy=-5).encode(
-    text=alt.condition(nearest, "y:Q", alt.value(" "))
+    text=when_near.then("y:Q").otherwise(alt.value(" "))
 )
 
 # Draw a rule at the location of the selection

tests/examples_arguments_syntax/multiline_tooltip_standard.py

@@ -28,10 +28,11 @@
     y="y:Q",
     color="category:N"
 )
+when_near = alt.when(nearest)
 
 # Draw points on the line, and highlight based on selection
 points = line.mark_point().encode(
-    opacity=alt.condition(nearest, alt.value(1), alt.value(0))
+    opacity=when_near.then(alt.value(1)).otherwise(alt.value(0))
 )
 
 # Draw a rule at the location of the selection
@@ -41,7 +42,7 @@
     groupby=["x"]
 ).mark_rule(color="gray").encode(
     x="x:Q",
-    opacity=alt.condition(nearest, alt.value(0.3), alt.value(0)),
+    opacity=when_near.then(alt.value(0.3)).otherwise(alt.value(0)),
     tooltip=[alt.Tooltip(c, type="quantitative") for c in columns],
 ).add_params(nearest)
 

tests/examples_arguments_syntax/multiple_interactions.py

@@ -61,32 +61,32 @@
 rating_radio = alt.binding_radio(options=ratings, name="Rating")
 rating_select = alt.selection_point(fields=['MPAA_Rating'], bind=rating_radio)
 
-rating_color_condition = alt.condition(
-    rating_select,
-    alt.Color('MPAA_Rating:N', legend=None),
-    alt.value('lightgray')
+rating_color = (
+    alt.when(rating_select)
+    .then(alt.Color('MPAA_Rating:N', legend=None))
+    .otherwise(alt.value("lightgray"))
 )
 
 highlight_ratings = base.add_params(
     rating_select
 ).encode(
-    color=rating_color_condition
+    color=rating_color
 ).properties(title="Radio Button Highlighting")
 
 # Boolean selection for format changes
 input_checkbox = alt.binding_checkbox(name="Big Budget Films ")
 checkbox_selection = alt.param(bind=input_checkbox)
 
-size_checkbox_condition = alt.condition(
-    checkbox_selection,
-    alt.Size('Hundred_Million_Production:Q'),
-    alt.SizeValue(25)
+size_checkbox = (
+    alt.when(checkbox_selection)
+    .then(alt.Size('Big_Budget_Film:N', scale=alt.Scale(range=[25, 150])))
+    .otherwise(alt.value(25))
 )
 
 budget_sizing = base.add_params(
     checkbox_selection
 ).encode(
-    size=size_checkbox_condition
+    size=size_checkbox
 ).properties(title="Checkbox Formatting")
 
-(filter_year | filter_genres) & (highlight_ratings | budget_sizing)
+(filter_year | budget_sizing) & (highlight_ratings | filter_genres)

tests/examples_arguments_syntax/scatter_linked_table.py

@@ -18,7 +18,7 @@
 points = alt.Chart(source).mark_point().encode(
     x='Horsepower:Q',
     y='Miles_per_Gallon:Q',
-    color=alt.condition(brush, alt.value('steelblue'), alt.value('grey'))
+    color=alt.when(brush).then(alt.value("steelblue")).otherwise(alt.value("grey"))
 ).add_params(brush)
 
 # Base chart for data tables

tests/examples_arguments_syntax/scatter_point_paths_hover.py

@@ -53,22 +53,21 @@
     "datum.country !== 'North Korea' && datum.country !== 'South Korea'"
 )
 
+search_matches = alt.expr.test(alt.expr.regexp(search_box, "i"), alt.datum.country)
+opacity = (
+    alt.when(hover_point_opacity, search_matches)
+    .then(alt.value(0.8))
+    .otherwise(alt.value(0.1))
+)
 # Points that are always visible (filtered by slider and search)
-visible_points = base.mark_circle(size=100).encode(
-    opacity=alt.condition(
-        hover_point_opacity 
-        & alt.expr.test(alt.expr.regexp(search_box, 'i'), alt.datum.country),
-        alt.value(0.8),
-        alt.value(0.1)
-        )
-    ).transform_filter(
-        x_select
-    ).add_params(
-        hover,
-        hover_point_opacity,
-        x_select
+visible_points = (
+    base.mark_circle(size=100)
+    .encode(opacity=opacity)
+    .transform_filter(x_select)
+    .add_params(hover, hover_point_opacity, x_select)
 )
 
+when_hover = alt.when(hover)
 hover_line = alt.layer(
     # Line layer
     base.mark_trail().encode(
@@ -81,12 +80,12 @@
             scale=alt.Scale(domain=[1955, 2005], range=[1, 12]),
             legend=None
         ),
-        opacity=alt.condition(hover, alt.value(0.3), alt.value(0)),
+        opacity=when_hover.then(alt.value(0.3)).otherwise(alt.value(0)),
         color=alt.value('#222222')
     ),
     # Point layer
     base.mark_point(size=50).encode(
-        opacity=alt.condition(hover, alt.value(0.8), alt.value(0)),
+        opacity=when_hover.then(alt.value(0.8)).otherwise(alt.value(0)),
     )
 )
 
@@ -108,7 +107,7 @@
     y='life_expect:Q',
     text='country:N',
     color=alt.value('black'),
-    opacity=alt.condition(hover, alt.value(1), alt.value(0))
+    opacity=when_hover.then(alt.value(1)).otherwise(alt.value(0))
 ).transform_window(
     rank='rank(life_expect)',
     sort=[alt.SortField('life_expect', order='descending')], 

tests/examples_arguments_syntax/scatter_with_layered_histogram.py

@@ -30,7 +30,11 @@
 
 color_scale = alt.Scale(domain=['M', 'F'],
                         range=['#1FC3AA', '#8624F5'])
-
+color = (
+    alt.when(selector)
+    .then(alt.Color("gender:N", scale=color_scale))
+    .otherwise(alt.value("lightgray"))
+)
 base = alt.Chart(source).properties(
     width=250,
     height=250
@@ -39,11 +43,7 @@
 points = base.mark_point(filled=True, size=200).encode(
     x=alt.X('mean(height):Q', scale=alt.Scale(domain=[0,84])),
     y=alt.Y('mean(weight):Q', scale=alt.Scale(domain=[0,250])),
-    color=alt.condition(
-        selector,
-        'gender:N',
-        alt.value('lightgray'),
-        scale=color_scale),
+    color=color,
 )
 
 hists = base.mark_bar(opacity=0.5, thickness=100).encode(

tests/examples_arguments_syntax/scatter_with_minimap.py

@@ -21,7 +21,7 @@
     .encode(
         x="date:T",
         y="temp_max:Q",
-        color=alt.condition(zoom, "weather", alt.value("lightgray")),
+        color=alt.when(zoom).then("weather").otherwise(alt.value("lightgray")),
     )
     .properties(
         width=200,

tests/examples_arguments_syntax/seattle_weather_interactive.py

@@ -28,7 +28,7 @@
         title='Maximum Daily Temperature (C)',
         scale=alt.Scale(domain=[-5, 40])
     ),
-    color=alt.condition(brush, color, alt.value('lightgray')),
+    color=alt.when(brush).then(color).otherwise(alt.value("lightgray")),
     size=alt.Size('precipitation:Q', scale=alt.Scale(range=[5, 200]))
 ).properties(
     width=550,
@@ -43,7 +43,7 @@
 bars = alt.Chart().mark_bar().encode(
     x='count()',
     y='weather:N',
-    color=alt.condition(click, color, alt.value('lightgray')),
+    color=alt.when(click).then(color).otherwise(alt.value("lightgray")),
 ).transform_filter(
     brush
 ).properties(

tests/examples_arguments_syntax/select_detail.py

@@ -42,6 +42,11 @@
 # Data is prepared, now make a chart
 
 selector = alt.selection_point(fields=['id'])
+color = (
+    alt.when(selector)
+    .then(alt.Color("id:O", legend=None))
+    .otherwise(alt.value("lightgray"))
+)
 
 base = alt.Chart(data).properties(
     width=250,
@@ -51,7 +56,7 @@
 points = base.mark_point(filled=True, size=200).encode(
     x='mean(x)',
     y='mean(y)',
-    color=alt.condition(selector, 'id:O', alt.value('lightgray'), legend=None),
+    color=color,
 )
 
 line = base.mark_line().encode(

tests/examples_arguments_syntax/us_employment.py

@@ -21,18 +21,15 @@
         "president": "Obama"
     }
 ])
+predicate = alt.datum.nonfarm_change > 0
 
 bars = alt.Chart(
     source,
     title="The U.S. employment crash during the Great Recession"
 ).mark_bar().encode(
     x=alt.X("month:T", title=""),
     y=alt.Y("nonfarm_change:Q", title="Change in non-farm employment (in thousands)"),
-    color=alt.condition(
-        alt.datum.nonfarm_change > 0,
-        alt.value("steelblue"),
-        alt.value("orange")
-    )
+    color=alt.when(predicate).then(alt.value("steelblue")).otherwise(alt.value("orange")),
 )
 
 rule = alt.Chart(presidents).mark_rule(

tests/examples_arguments_syntax/us_state_capitals.py

@@ -32,12 +32,12 @@
 
 text = base.mark_text(dy=-5, align='right').encode( 
     alt.Text('city', type='nominal'),
-    opacity=alt.condition(~hover, alt.value(0), alt.value(1))
+    opacity=alt.when(~hover).then(alt.value(0)).otherwise(alt.value(1))
 )
 
 points = base.mark_point().encode(
     color=alt.value('black'),
-    size=alt.condition(~hover, alt.value(30), alt.value(100))
+    size=alt.when(~hover).then(alt.value(30)).otherwise(alt.value(100))
 ).add_params(hover)
 
 background + points + text