Line Chart with Layered Aggregates

This example shows how to make a multi-series line chart of the daily closing stock prices for AAPL, AMZN, GOOG, IBM, and MSFT between 2000 and 2010, along with a layered rule showing the average values.

Method syntax

import altair as alt
from vega_datasets import data

source = data.stocks()

base = alt.Chart(source).properties(width=550)

line = base.mark_line().encode(
    x='date',
    y='price',
    color='symbol'
)

rule = base.mark_rule().encode(
    y='average(price)',
    color='symbol',
    size=alt.value(2)
)

line + rule

Attribute syntax

import altair as alt
from vega_datasets import data

source = data.stocks()

base = alt.Chart(source).properties(width=550)

line = base.mark_line().encode(
    x='date',
    y='price',
    color='symbol'
)

rule = base.mark_rule().encode(
    y='average(price)',
    color='symbol',
    size=alt.value(2)
)

line + rule
# No channel encoding options are specified in this chart
# so the code is the same as for the method-based syntax.