Axis labels are not shown for all subplots when using plotly express, facets and string labels

[b-a0]

Problem summary

Whenever I have the following combination:

• plotly express
• facet plots
• labels used for axis are strings

The first subplot shows the axis labels properly, but all following subplots don't show labels at all:

If the axis labels are numbers, there is no problem.

Reproducible example

I originally created these plots in Python (plotly 5.18.0) and then used the .to_json(pretty=True) method to obtain the Javascript for the codepens.

• Manually building up the figure using graph_objects and make_subplots I get the following working visualization: https://codepen.io/sl1970/pen/BaMvNbp
• If I use the convenient plotly.express library and the facet argument I get this broken visualization (no axis labels on the right plot): https://codepen.io/sl1970/pen/jOdXPoa

Original Python code

If necessary, this is the original Python code I used

import pandas as pd
import plotly.express as px
from plotly.subplots import make_subplots
import plotly.graph_objects as go

df = pd.DataFrame(
    {
        "age": { "0": "Adult", "1": "Adult", "2": "Adult", "3": "Adult", "4": "Adult", "5": "Kid", "6": "Kid", "7": "Kid", "8": "Kid", "9": "Kid", },
        "favourite_food": { "0": "Pizza", "1": "Noodles", "2": "Pizza", "3": "Pizza", "4": "Pizza", "5": "Burger", "6": "Pancake", "7": "Noodles", "8": "Pizza", "9": "Pancake", },
        "favourite_drink": { "0": "Beer", "1": "Tea", "2": "Beer", "3": "Wine", "4": "Coffee", "5": "Coffee", "6": "Water", "7": "Beer", "8": "Tea", "9": "Wine", },
        "max_running_speed": { "0": 4.7362803248, "1": 16.7084927714, "2": 8.1135697835, "3": 1.0704264989, "4": 4.6330187561, "5": 6.331593807, "6": 16.5221040135, "7": 3.2256763127, "8": 4.3084468631, "9": 6.3677742299, },
        "number_of_bicycles": { "0": 4, "1": 2, "2": 1, "3": 3, "4": 4, "5": 3, "6": 3, "7": 3, "8": 4, "9": 2, },
    }
)
df.set_index("age", inplace=True)


working = make_subplots(rows=1, cols=2, subplot_titles=["Food", "Drink"])

working.add_trace( go.Histogram( histfunc="count", histnorm="percent", x=df.loc["Adult"].favourite_food, name="Adult", legendgroup="Adult", ), row=1, col=1, )
working.add_trace( go.Histogram( histfunc="count", histnorm="percent", x=df.loc["Kid"].favourite_food, name="Kid", legendgroup="Kid" ), row=1, col=1, )
working.add_trace( go.Histogram( histfunc="count", histnorm="percent", x=df.loc["Adult"].favourite_drink, name="Adult", legendgroup="Adult", ), row=1, col=2, )
working.add_trace( go.Histogram( histfunc="count", histnorm="percent", x=df.loc["Kid"].favourite_drink, name="Kid", legendgroup="Kid" ), row=1, col=2, )
working.show()

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

Related

• Related post on SO
• Related post on Plotly community

[lvlte]

The issue might rather be in px.express (ie. in plotly.py rather than plotly.js) since you managed to get labels working using go.Histogram(). It appears px.histogram() with facet_col explicitly set the same bingroup 'x' to every trace, while the default (implicit, working) behavior is only the traces that are on the same subplot belong to the same bingroup. So you can fix the issue by adding fig.update_traces(bingroup='x2', row=1, col=2) to your original code, and maybe move the issue to https://github.com/plotly/plotly.py.

[b-a0]

Thank you, I can confirm that fig.update_traces(bingroup='x2', row=1, col=2) works arround the issue. I am fine with this issue being moved to the plotly.py repo, but unfortunately I cannot move it myself.

@plotly, can you please move this issue to the right repository? Thanks in advance!

[b-a0]

Closing as I opened this same issue at https://github.com/plotly/plotly.py