I was trying to give text labels on some altair chart linked to a selected interval from another chart. I realize that the text given by "mark_text ()" doesn't show completely at the last points of the chart where the domain in the x-axis is specified to be the interval selected, also I didn't know how to specify the format so the dates will be given just as yyyy-mm or month-year (don't want to display the day).
Another thing that I realized, is when one specifies the tooltip doesn't show at all when the domain on the x-axis of the graph is also linked to an interval selected in another chart
, that's the reason I used the mark_text()
the code I'm using is the following
import altair as alt
from vega_datasets import data
nearest = alt.selection_single(nearest=True, on='mouseover',
encodings=['x','y'], empty='none')
interval = alt.selection_interval(encodings=['x'])
weather = data.seattle_weather()
base = alt.Chart(weather).mark_rule(size=2).encode(
x='date:T')
chart = base.mark_line().encode(
x=alt.X('date:T', scale=alt.Scale(domain=interval.ref())),
y='temp_max:Q',).properties(
width=800,
height=300)
text=base.mark_text(align='left', dx=5, dy=5).encode(
y='temp_max:Q',
text=alt.condition(nearest, 'label:N', alt.value(' '))
).transform_calculate(label='"Date: " + format(datum.date, "") '
).properties(selection=nearest,width=800,
height=300)
point=base.mark_point().encode(y='temp_max:Q',opacity=alt.condition(nearest, alt.value(1), alt.value(0)))
view = base.mark_line().add_selection(
interval).properties(width=800, height=20)
(point+text+chart) &view
It looks like you're trying to create a tooltip using a layer, and this is the cause of many of the problems you're having. Have you considered using the tooltip encoding?
import altair as alt
from vega_datasets import data
nearest = alt.selection_single(nearest=True, on='mouseover',
encodings=['x','y'], empty='none')
interval = alt.selection_interval(encodings=['x'])
weather = data.seattle_weather()
line = alt.Chart(weather).mark_line().encode(
x=alt.X('date:T', scale=alt.Scale(domain=interval)),
y='temp_max:Q'
).properties(
width=800,
height=200
)
point = line.mark_point().encode(
tooltip='yearmonth(date):N',
opacity=alt.condition(nearest, alt.value(1), alt.value(0))
).add_selection(nearest)
view = alt.Chart(weather).mark_line().encode(
x='date:T',
).properties(
width=800,
height=20
).add_selection(interval)
(point + line) & view