Tidy natural_disasters.py example

altair/examples/natural_disasters.py

@@ -1,29 +1,52 @@
 """
-Natural Disasters
------------------
-This example shows a visualization of global deaths from natural disasters.
+Global Deaths from Natural Disasters
+------------------------------------
+This example shows a proportional symbols visualization of deaths from natural disasters by year and type.
 """
 # category: case studies
 import altair as alt
 from vega_datasets import data
 
 source = data.disasters.url
 
-alt.Chart(source).mark_circle(
+alt.Chart(source).transform_filter(
+    alt.datum.Entity != 'All natural disasters'
+).mark_circle(
     opacity=0.8,
     stroke='black',
-    strokeWidth=1
+    strokeWidth=1,
+    strokeOpacity=0.4
 ).encode(
-    alt.X('Year:O', axis=alt.Axis(labelAngle=0)),
-    alt.Y('Entity:N'),
-    alt.Size('Deaths:Q',
-        scale=alt.Scale(range=[0, 4000]),
-        legend=alt.Legend(title='Annual Global Deaths')
+    x=alt.X('Year:T', title=None, scale=alt.Scale(domain=['1899','2018'])),
+    y=alt.Y(
+        'Entity:N',
+        sort=alt.EncodingSortField(field="Deaths", op="sum", order='descending'),
+        title=None
+    ),
+    size=alt.Size('Deaths:Q',
+        scale=alt.Scale(range=[0, 2500]),
+        legend=alt.Legend(title='Deaths', clipHeight=30, format='s')
     ),
-    alt.Color('Entity:N', legend=None)
+    color=alt.Color('Entity:N', legend=None),
+    tooltip=[
+        "Entity:N", 
+        alt.Tooltip("Year:T", format='%Y'), 
+        alt.Tooltip("Deaths:Q", format='~s')
+    ],
 ).properties(
     width=450,
-    height=320
-).transform_filter(
-    alt.datum.Entity != 'All natural disasters'
+    height=320,
+    title=alt.TitleParams(
+        text="Global Deaths from Natural Disasters (1900-2017)",
+        subtitle="The size of the bubble represents the total death count per year, by type of disaster",
+        anchor='start'
+    )
+).configure_axisY(
+    domain=False,
+    ticks=False,
+    offset=10
+).configure_axisX(
+    grid=False,
+).configure_view(
+    stroke=None
 )