Merge pull request #1520 from iliatimofeev/it-violin-plot

Violin plot (a kind of)

altair/examples/violine_plot.py

@@ -0,0 +1,51 @@
+"""
+Violinplot
+----------
+This example shows how to make a king of a Violinplot.
+"""
+# category: other charts
+import altair as alt
+from altair import datum
+from vega_datasets import data
+
+source = data.cars.url
+
+violinplot =  alt.Chart(source).transform_filter(
+    datum.Miles_per_Gallon > 0
+).transform_bin(
+    ['bin_max', 'bin_min'], field='Miles_per_Gallon', bin=alt.Bin(maxbins=20)
+).transform_calculate(
+    binned=(datum.bin_max + datum.bin_min) / 2
+).transform_aggregate(
+    value_count='count()', groupby=['Origin', 'binned']
+).transform_impute(
+    impute='value_count', groupby=['Origin'], key='binned', value=0
+).mark_area(
+    interpolate='monotone',
+    orient='horizontal'
+).encode(
+    x=alt.X(
+        'value_count:Q',
+        title=None,
+        stack='center',
+        axis=alt.Axis(labels=False, values=[0],grid=False, ticks=True),
+    ),
+    y=alt.Y('binned:Q', bin='binned', title='Miles per Gallon'),
+    color=alt.Color('Origin:N', legend=None),
+    column=alt.Column(
+        'Origin:N',
+        header=alt.Header(
+            titleOrient='bottom',
+            labelOrient='bottom',
+            labelPadding=0,
+        ),
+    ),
+).properties( 
+    width=80 
+).configure_facet(
+    spacing=0
+).configure_view(
+    stroke=None
+)
+
+violinplot