CODEWITHSUNDEEP
pythonaltair
fitzme
fitzme

Reputation: 292

Text above axes of an interactive Altair plot

I have been following the advice on the question here to place various tips/information on my plots in Altair for a little while now. However, this advice does not work if the Altair plot is set to interactive() - it appears to me that enabling the scale binding prevents any plot objects from appearing outside of the rectangular axes.

Here is a reproducing example based on that link: compare the generated plots with/without the commented interactive() line at the end.

    import altair as alt
    import pandas as pd
    import numpy as np

    df = pd.DataFrame({'x': np.linspace(0, 4, 1000)})
    df['y'] = np.sin(2 * np.pi * df['x'])

    select_point = alt.selection_single(fields=('x',), nearest=True, on='mouseover', empty='none')
    line = alt.Chart(df).mark_line().encode(
        x='x:Q',
        y='y:Q',
    )
    points = line.mark_point(filled=True, size=100).encode(
        opacity=alt.condition(select_point, alt.value(1.0), alt.value(0.0)),
    ).add_selection(select_point)
    text1 = alt.Chart(df, width=600, height=400).mark_text(
        align='left', baseline='bottom', dx=+5, fontSize=12,
    ).encode(
        x=alt.value(0.0),
        y=alt.value(-1),
        text='_label:N',
        opacity=alt.condition(select_point, alt.value(1.0), alt.value(0.0)),
    ).transform_calculate(
        _label='"ABOVE AXES x = " + format(datum.x, ".2f") + ", y = " + format(datum.y, ".2f")',
    )
    text2 = alt.Chart(df, width=600, height=400).mark_text(
        align='left', baseline='bottom', dx=+5, fontSize=12,
    ).encode(
        x=alt.value(0.0),
        y=alt.value(12),
        text='_label:N',
        opacity=alt.condition(select_point, alt.value(1.0), alt.value(0.0)),
    ).transform_calculate(
        _label='"INSIDE AXES x = " + format(datum.x, ".2f") + ", y = " + format(datum.y, ".2f")',
    )
    chart = alt.layer(line, points, text1, text2)
    # chart = chart.interactive()

Interactive OFF Interactive ON

Additional information, in case it is helpful/relevant:

Bottom line question: how can I get text to appear outside of the axes boundaries in Altair when the plot is set to be interactive?

Upvotes: 4

Views: 685

Answers (1)

jakevdp
jakevdp

Reputation: 86533

Pass clip=False to mark_text(), and text will be visible outside the axis.

The clip parameter default to False for non-bound scales, and True for bound scales.

Upvotes: 2

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