How to show text on a heatmap with Plotly?

Question

I am trying to show the z items as text on a Plotly heatmap. I am using the latest version (5.5.0) and following the exact example shown on the Plotly Heatmaps webpage ( https://plotly.com/python/heatmaps/ ), see the section "Text on Heatmap Points" near the bottom.

My code is their example code, which is:

figHeatmap = go.Figure(
                       data=go.Heatmap(
                                       z=[[1,20,30], [20,1,60], [30,60,1]], 
                                       text=[['1','2','3'],['4','5','6'],['7','8','9']], 
                                       texttemplate="%{text}", 
                                       textfont={"size":20}
                                       )
                      )

When I render my app in a webpage, what I see is this:

But on their site it shows with the labels:

I don't get any errors when I run my app, and the labels do indeed show when I hover over the heatmap, but the text is not displaying on the heatmap as it should. Since I'm using their exact example, I don't understand what could be going wrong. Any thoughts?

[EDIT]: It seems like this might be an issue with Dash. When I run the example interactively, I do indeed get the text labels. But my application is part of a Dash app, and that is where I am not seeing the rendered labels.

Answer 1

• This is a new feature in 5.5.0 https://github.com/plotly/plotly.py/releases . After installing and restarting my jupyter kernel, this did not work. Required restart of complete jupyter environment
• the documented example using go https://plotly.com/python/heatmaps/#text-on-heatmap-points plus note in release notes auto_text parameter, I explored this.
• below shows use of px and also go by adding numbers as text as well

import plotly.express as px
import plotly.graph_objects as go
import inflect

p = inflect.engine()
df = px.data.medals_wide(indexed=True)
fig = px.imshow(df, text_auto=True)
fig2 = go.Figure(fig.data, fig.layout)
fig2 = fig2.update_traces(text=df.applymap(p.number_to_words).values, texttemplate="%{text}", hovertemplate=None)

fig.show()
fig2.show()