Error Bars with Standard Deviation

This example shows how to show error bars with standard deviation using crop yields data of different in the years of 1930s.

Method syntax

import altair as alt
from altair.datasets import data

source = data.barley()

error_bars = alt.Chart(source).mark_errorbar(extent='stdev').encode(
  x=alt.X('yield').scale(zero=False),
  y=alt.Y('variety')
)

points = alt.Chart(source).mark_point(filled=True, color='black').encode(
  x=alt.X('mean(yield)'),
  y=alt.Y('variety'),
)

error_bars + points

Attribute syntax

import altair as alt
from altair.datasets import data

source = data.barley()

error_bars = alt.Chart(source).mark_errorbar(extent='stdev').encode(
  x=alt.X('yield:Q', scale=alt.Scale(zero=False)),
  y=alt.Y('variety:N')
)

points = alt.Chart(source).mark_point(filled=True, color='black').encode(
  x=alt.X('yield:Q', aggregate='mean'),
  y=alt.Y('variety:N'),
)

error_bars + points