Adding Types to a Chart in Altair
You can add type information to an altair chart. You can declare time-based features, nominal features and quantitative features. Specifying the color is also easy.
The bar chart at the end of this video is created via;
(alt.Chart(plot_df)
.mark_bar(color='lightblue')
.encode(x='date:T', y='births:Q', color='month:N', tooltip=['date', 'births'])
.properties(height=200))
Encoding :T
, :Q
, :O
and :N
In short the types in Altair allow you to declare:
:T
a datetime-like field:Q
a quantitative field:O
an ordered categorical field:N
a non-ordered categorical field
Setting these types typically has consequence for how the .encode()
method
will render the end-result. It can handle type-casting, but you may want to
resort to methods like alt.Color
if you want full control over how legends
are rendered.