How to show axis labels of all subplots when the labels are strings?

Question

Problem summary

Whenever I try to create a plot with plotly express 5.18.0 containing a subplot and axes labels that are not numbers, I only get labels for the first subplot subsequent subplots show empty axis labels.

How can I ensure that all subplots show their respective axes labels, even if they contain strings?

Example data

import numpy as np
import pandas as pd
import plotly.express as px

N = 100
food = ["Dim sum", "Noodles", "Burger", "Pizza", "Pancake"]
drink = ["Beer", "Wine", "Soda", "Water", "Fruit juice", "Coffee", "Tea"]
df = pd.DataFrame(
    {
        "age": np.random.randint(8, 99, N),
        "favourite_food": np.random.choice(food, N, replace=True),
        "favourite_drink": np.random.choice(drink, N, replace=True),
        "max_running_speed": np.random.random(N)*20,
        "number_of_bicycles": np.random.randint(0, 5, N)
    }
)
df.age.replace({range(0, 19): "Kid", range(19, 100): "Adult"}, inplace=True)

Random 5 rows:

	age	favourite_food	favourite_drink	max_running_speed	number_of_bicycles
0	Adult	Dim sum	Wine	8.57536	2
65	Kid	Pizza	Water	9.45698	1
57	Kid	Pancake	Beer	11.1445	0
84	Adult	Dim sum	Soda	8.80699	0
45	Adult	Pizza	Fruit juice	17.7258	4

Demonstration of problem

If I now create a figure with two subplots:

• First subplot contains the distribution of the max. running speed (a number)
• Second subplot contains the distribution of the number of bicycles (a number)

For convenience I use the facet_col argument in combination with the wide-form support of plotly express and the formatting updates I found in this related Q&A):

px.histogram(
    df,
    x=["max_running_speed", "number_of_bicycles"],
    facet_col="variable",
    color="age",
    barmode="group",
    histnorm="percent",
    text_auto=".2r",
).update_xaxes(matches=None, showticklabels=True).update_yaxes(matches=None, showticklabels=True)

All works as it should ✅: I get separate ranges x- and y-axes and I get separate labels on the x-axes.

Now I do the same, but for the columns with text data:

px.histogram(
    df,
    x=["favourite_food", "favourite_drink"],
    facet_col="variable",
    color="age",
    barmode="group",
    histnorm="percent",
    text_auto=".2r",
).update_xaxes(matches=None, showticklabels=True).update_yaxes(matches=None, showticklabels=True)

Now there's a problem ❌: The x-axis of the right plot does not show the names of the favourite drinks.

What I've tried

I checked the underlying data JSON object, as I noticed that when I hover over the bars of the right plot, the "value" field is empty:

But when I inspect the JSON object in the .data key of the figure, I see that x-values are present for both histograms:

Answer 1

One of the plotly contributors suggested I use the .update_traces(bingroup=None) on my figure. This indeed shows the missing categories on the right plot and is a viable workaround for now.