Clarify that a special field name is required to render images in tooltips
@@ -3,7 +3,9 @@ Image tooltip
-------------
This example shows how to render images in tooltips.
Either URLs or local file paths can be used to reference
-the images.
+the images. To render the image, you must use the special
+column name "image" in your data and pass it as a list to
+the tooltip encoding.
"""
# category: interactive charts
@@ -17,5 +19,5 @@ source = pd.DataFrame.from_records(
alt.Chart(source).mark_circle(size=200).encode(
x='a',
y='b',
- tooltip=['image'] # Must be a list for the image to render
+ tooltip=['image'] # Must be a list containing a field called "image"
)
