Python Altair 在选择时生成表格

如何解决Python Altair 在选择时生成表格

我有一个包含一堆分箱数据的直方图，我想知道如果我从直方图中选择一个条形，是否可以说生成一个表格，它会显示原始数据框中的数据。

解决方法

您可以使用 mark_text 创建表格的外观。这是an example based on this page in the docs：

import altair as alt
from vega_datasets import data

source = data.cars()

# Brush for selection
brush = alt.selection(type='interval')

# Scatter Plot
points = alt.Chart(source).mark_point().encode(
    x='Horsepower:Q',y='Miles_per_Gallon:Q',color=alt.condition(brush,alt.value('steelblue'),alt.value('grey'))
).add_selection(brush)

# Base chart for data tables
ranked_text = alt.Chart(source).mark_text(align='right').encode(
    y=alt.Y('row_number:O',axis=None)
).transform_window(
    row_number='row_number()'
).transform_filter(
    brush
).transform_window(
    rank='rank(row_number)'
).transform_filter(
    alt.datum.rank<16
)

# Data Tables
horsepower = ranked_text.encode(text='Horsepower:N').properties(title=alt.TitleParams(text='Horsepower',align='right'))
mpg = ranked_text.encode(text='Miles_per_Gallon:N').properties(title=alt.TitleParams(text='MPG',align='right'))
origin = ranked_text.encode(text='Origin:N').properties(title=alt.TitleParams(text='Origin',align='right'))
text = alt.hconcat(horsepower,mpg,origin) # Combine data tables

# Build chart
alt.hconcat(
    points,text
).resolve_legend(
    color="independent"
).configure_view(strokeWidth=0)

For a histogram,things are slightly different due to current limitation in Vega-Lite 并且您需要创建第二个过滤层以直观地显示直方图中的选择。

import altair as alt
from vega_datasets import data


source = data.cars()

# Brush for selection
brush = alt.selection(type='single',encodings=['x'])

# Histogram base
hist_base = alt.Chart(source).mark_bar(color='grey').encode(
    x=alt.X('Horsepower:Q',bin=True),y='count()',).add_selection(brush)

# Histogram selection
hist_selection = alt.Chart(source).mark_bar().encode(
    x=alt.X('Horsepower:Q',).transform_filter(brush)

# Base chart for data tables
ranked_text = alt.Chart(source).mark_text(align='right').encode(
    y=alt.Y('row_number:O',origin) # Combine data tables

# Build chart
alt.hconcat(
    hist_base+hist_selection,text
).resolve_legend(
    color="independent"
).configure_view(strokeWidth=0)