[英]Bar Chart in Altair: ValueError: Faceted charts cannot be layered
[英]Rolling average on a layered faceted chart in Altair
我成功地讓圖層在多面圖表中工作,並讓滾動平均值在分層圖表中工作。 我現在想將兩者結合起來,即在分層多面圖表中具有滾動平均值。
直觀地將兩者結合起來會給我一個錯誤-
Javascript Error: Cannot read property 'concat' of undefined
This usually means there's a typo in your chart specification. See the javascript console for the full traceback.
代碼(給出上述錯誤):
# Data Preparation
df = pd.read_csv('https://raw.githubusercontent.com/CSSEGISandData/COVID-19/master/csse_covid_19_data/csse_covid_19_time_series/time_series_covid19_confirmed_global.csv')
idf = df[df['Country/Region'] == 'India']
idf = idf[df.columns[4:]]
idf = idf.T
idf = idf.reset_index()
idf.columns = ['day', 'case']
idf['country'] = 'india'
gdf = df[df['Country/Region'] == 'Germany']
gdf = gdf[df.columns[4:]]
gdf = gdf.T
gdf = gdf.reset_index()
gdf.columns = ['day', 'case']
gdf['country'] = 'germany'
fdf = pd.concat([idf,gdf])
# Charting
a = alt.Chart().mark_bar(opacity=0.5).encode(
x='day:T',
y='case:Q'
)
c = alt.Chart().mark_line().transform_window(
rolling_mean='mean(case:Q)',
frame=[-7, 0]
).encode(
x='day:T',
y='rolling_mean:Q'
)
alt.layer(a, c, data=fdf).facet(alt.Column('country', sort=alt.EncodingSortField('case', op='max', order='descending')))
如果您刪除transform_window
並將y='rolling_mean:Q'
替換為y='case:Q'
,您將獲得分層多面圖。 正是這張圖表,我想要一個 7 天的滾動平均值。
嘗試通過 sort=[{'field': 'date'}] https://vega.github.io/vega-lite/docs/window.html#cumulative-frequency-distribution 使用 transform_window
或:https://altair-viz.github.io/gallery/scatter_marginal_hist.html
https://altair-viz.github.io/gallery/layered_chart_with_dual_axis.html#layered-chart-with-dual-axis
https://altair-viz.github.io/gallery/parallel_coordinates.html#parallel-coordinates-example
import altair as alt
from vega_datasets import data
source = data.iris()
alt.Chart(source).transform_window(
index='count()'
).transform_fold(
['petalLength', 'petalWidth', 'sepalLength', 'sepalWidth']
).mark_line().encode(
x='key:N',
y='value:Q',
color='species:N',
detail='index:N',
opacity=alt.value(0.5)
).properties(width=500)
https://altair-viz.github.io/user_guide/compound_charts.html?highlight=repeat#horizontal
import altair as alt
from vega_datasets import data
iris = data.iris.url
chart1 = alt.Chart(iris).mark_point().encode(
x='petalLength:Q',
y='petalWidth:Q',
color='species:N'
).properties(
height=300,
width=300
)
chart2 = alt.Chart(iris).mark_bar().encode(
x='count()',
y=alt.Y('petalWidth:Q', bin=alt.Bin(maxbins=30)),
color='species:N'
).properties(
height=300,
width=100
)
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