在altair中重命名工具提示

Question

我正在尝试使用下面的代码在Altair中绘制一个图表。

tot_matches_played = alt.Chart(mpt).mark_bar().encode(
  alt.X('Team',axis=alt.Axis(title='Teams Played in IPL'), sort=alt.EncodingSortField(field='Number_of_matches_played:Q', op='count', order='ascending')),  
  alt.Y('Number_of_matches_played:Q' ),
  tooltip=['sum(Number_of_matches_played)']
)

但由于工具提示名称很奇怪，我想在图表上使用"as“将其重命名，如下所示。

tot_matches_played = alt.Chart(mpt).mark_bar().encode(
  alt.X('Team',axis=alt.Axis(title='Teams Played in IPL'), sort=alt.EncodingSortField(field='Number_of_matches_played:Q', op='count', order='ascending')),  
  alt.Y('Number_of_matches_played:Q' ),
  tooltip=['sum(Number_of_matches_played)' as total_matches]
)

如何重命名工具提示，使其对查看图表的用户更具可读性。

Answer 1

您可以通过alt.Tooltip调整title输出

tot_matches_played = alt.Chart(mpt).mark_bar().encode(
  alt.X('Team',axis=alt.Axis(title='Teams Played in IPL'), sort=alt.EncodingSortField(field='Number_of_matches_played:Q', op='count', order='ascending')),  
  alt.Y('Number_of_matches_played:Q' ),
  tooltip=[alt.Tooltip('sum(Number_of_matches_played)', title='matches played')]
)

Answer 2

作为对jakevdp答案的补充，如果有人遇到这种情况，并且需要为两个不同的功能(就像我对地图所做的那样)做一个替代标题，代码的"tooltip=“部分将如下所示：

tooltip=[alt.Tooltip('properties.feature1:O', title="Feature 1"), alt.Tooltip('properties.feature2:Q', title="Feature 2")]