Altair 将对数线性回归添加到带有选择的图表中

Question

我有一个 Altair 散点图，绘制了日期与数量。该图表包括一个选择菜单，用于突出显示来自不同域的点。

我想在其上添加逻辑回归，transform_regression。

但是我在执行时遇到错误。

这是我的代码：

import altair as alt
alt.themes.enable('fivethirtyeight')
selection = alt.selection_multi(fields=['Domain'], bind='legend')
chart = alt.Chart(df, width=1100, height=600, 
          title="Parameter count of ML systems through time")\
.mark_point(size=120, filled=False).encode(
  x=alt.X('Publication date:T'),
  y=alt.Y('Parameters:Q',scale=alt.Scale(type='log'), axis=alt.Axis(format=".1e")),
  color='Domain',
  shape = 'Domain',
  tooltip=['System', 
           'Reference', 
           'Publication date', 
           alt.Tooltip('Parameters', format=".1e"), 
           'Domain'],
  opacity=alt.condition(selection, alt.value(1), alt.value(0.2))
).add_selection(
    selection
)

regression = chart.transform_regression(
    on="Publication date", regression="Parameters", groupby=["Domain"]
).mark_line()

alt.layer(chart, regression).configure_axis(labelFontSize=20,titleFontSize=30).configure_legend(
    titleFontSize=20,
    labelFontSize =18,
    gradientLength=400,
    gradientThickness=30,
    symbolSize = 130
)

这是我得到的错误：Javascript Error: Duplicate signal name: "selector027_tuple" This usually means there's a typo in your chart specification. See the javascript console for the full traceback.

我无法理解 javascript 控制台的输出，但它显示如下：

Uncaught (in promise) Javascript Error: Duplicate signal name: "selector028_tuple"<br>This usually means there's a typo in your chart specification. See the javascript console for the full traceback.
Promise.catch (async)
displayChart @ VM1182:32
(anonymous) @ VM1182:45
load (async)
(anonymous) @ VM1182:19
loadScript @ VM1182:15
(anonymous) @ VM1182:43

Answer 1

由于回归图是基于已添加选择的点图，因此在对这两个图表进行分层时，您将添加两次。相反，创建没有选择的点图表并将其仅添加到图层中的一个图表：

alt.layer(chart.add_selection(selection), regression)

或一次到分层图表：

alt.layer(chart, regression).add_selection(selection)

Altair 将对数线性回归添加到带有选择的图表中

Altair add log linear regression to chart with selection

python

altair