add ability to hide missing data from hover tooltip

I have a dataframe column with some missing values which I want to include in hover_data. Is it possible to show the column in the hover tooltip only if there's value for the currently hovered point? The current default behavior is to show col_name=%{customdata[0]} for missing values. I think it would be better to show nothing at all.

import plotly.express as px

df = px.data.gapminder().query("continent=='Oceania'")

df["pop"] = None

fig = px.line(
    df,
    x="year",
    y="lifeExp",
    color="country",
    hover_data=["pop"],
    title="layout.hovermode='closest' (the default)",
)
fig.update_traces(mode="markers+lines")

fig.show()

Commenting out these two lines

df["pop"] = None

and/or just this one:

hover_data=["pop"],

removes pop:= %{customdata[0]} from tooltips.

@empet

@empet You misunderstood. I do want the population data in the tooltip, just not for points where that data is missing. The line

df["pop"] = None

is just to simulate missing data.

@janosh

@janosh
I thought you want remove customdata just for this example, because here if you are dsiplaying fig.data[0], and fig.data[1] you'll see that in both cases the elements of customdata are all None:

'customdata': array([[None],
                         [None],
                         [None],
                         [None],
                         [None],
                         [None],
                         [None],
                         [None],
                         [None],
                         [None],
                         [None],
                         [None]], dtype=object)

I know. They're all None because I was too lazy to only set the value for that point to None which is being hovered in the screenshot.

I think that a solution is to convert customdata to strings, and set ' ', instead of None:

import numpy as np
import plotly.graph_objects as go
N=24
vals = np.random.randint(1000, 2001, N).astype(str)
#or vals = (7*np.random.rand(24)).astype(str)
                       
I = np.random.randint(0, N, 12)
vals[I]=''

fig=go.Figure(go.Scatter(x=np.arange(0,N), y=4+5*np.random.rand(N), customdata=vals,
              hovertemplate='vals: %{customdata}'))
fig.show()

Unfortunately we cannot access individual elements in customdata to set hovertemplate with an if else , depending on whether an element is ' ', or not.

Is there any other way to slove the problem? l have a stacked line graph with same question, some point missing value in stack and display %{customdata} in hover. i can not convert customdata to strings, and set ' ', in fact this point even not in my dataframe, just because other point in same stack it appeard lije this:

Is there any development on this issue? I would also like my hovertip to skip that specific customdata if it's np.nan

I also have the same problem. Will be nice if the package owners will give it high priority.

Ditto.

The last workaround, and generally filling a dataframe with a string, now throws an error in pandas, and will soon not be allowed, for columns with dtypes that are not strings (datetime, float, etc) I believe. That's just to say that a solution here soonish would be a big value add :)

I think my ideal preference as far as implementation goes would be to have a layout or trace setting where you could give a value for missing data, e.g. "-", and missing data would be sniffed using pd.isnull because things like NaT will be missed otherwise I think.

@gvwilson

I appreciate the need, but realistically, our team isn't going to get to this in the plotting layer any time soon. We'd be happy to prioritize review of a community PR if someone wants to put one together. Thanks - @gvwilson

@alexscott-ff

As of plotly.py v6.4.0, this situation is handled much better: In the case of missing data, a hyphen is displayed rather than the raw template string (implemented by plotly/plotly.js#7577 in plotly.js). So basically the behavior proposed by @alexscott-ff.

A different fallback string besides a hyphen can be used by setting the trace's hovertemplatefallback attribute.

I'll leave this issue open, though, since it's still not possible to hide the hovertext entry entirely when data is missing.

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add ability to hide missing data from hover tooltip #3515

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add ability to hide missing data from hover tooltip #3515

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empet commented on Dec 27, 2021

janosh commented on Dec 27, 2021

empet commented on Dec 27, 2021

janosh commented on Dec 27, 2021

empet commented on Dec 27, 2021

krieg0102 commented on Aug 18, 2022

lijecaru commented on Aug 18, 2022

yaelbh commented on Aug 25, 2022

sarangof commented on Mar 27, 2023

alexscott-ff commented on Apr 11, 2025

gvwilson commented on Apr 11, 2025

emilykl commented on Aug 28, 2026

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