Plotly: How to edit unified hoverlabel?

Question

I am generating a graph with two different contour lines. When I hover the mouse over the graph it compares a menu with the values of the two contours as in the image:

I obtained this result with this code:

# IMPORT
import plotly.graph_objs as go
import plotly.offline as pyo
import numpy as np

# CONSTANTS SET UP
N = 11
x_min = 0
x_max = 10
y_min = 0
y_max = 10
fontsize = 18

# COLORS SET UP
blue = '#6683f3'
orange = '#ff9266'
black = '#212121'

# DEFINE THE MESH GRID
x = np.linspace(x_min, x_max, N)
y = np.linspace(y_min, y_max, N)
XX, YY = np.meshgrid(x, y)

# CALCULATE Z1 AND Z2
Z1 = XX + YY
Z2 = XX - YY

# DEFINE THE TRACES LIST
data = [go.Contour(z = Z1,
                   transpose = True,
                   name = 'Z1',
                   zmin = np.min(Z1),
                   zmax = np.max(Z1) + 1,
                   hovertemplate = 'Z1 = %{z: .0f}<extra></extra>',
                   contours_coloring = 'lines',
                   showscale = False,
                   showlegend = True,
                   colorscale = [[0, orange], [1, orange]],
                   line_width = 4,
                   ncontours = 20,
                   contours = dict(showlabels = True,
                                   labelformat = '.0f',
                                   labelfont = dict(size = 18))),
        go.Contour(z = Z2,
                   transpose = True,
                   name = 'Z2',
                   zmin = np.min(Z2),
                   zmax = np.max(Z2) + 1,
                   hovertemplate = 'Z2 = %{z: .0f}<extra></extra>',
                   contours_coloring = 'lines',
                   showscale = False,
                   showlegend = True,
                   colorscale = [[0, blue], [1, blue]],
                   line_width = 4,
                   ncontours = 20,
                   contours = dict(showlabels = True,
                                   labelformat = '.0f',
                                   labelfont = dict(size = fontsize)))]

# DEFINE THE LAYOUT
layout = go.Layout(plot_bgcolor = black,
                   hovermode = 'x')

# DEFINE THE FIGURE
figure = go.Figure(data = data,
                   layout = layout)

# IMPROVE LEGEND AND HOVERLABEL ASPECT
figure.update_layout(legend = dict(itemsizing = 'constant',
                                   font = dict(size = fontsize)),
                     hoverlabel = dict(font_size = fontsize))

# PLOT THE FIGURE
pyo.plot(figure)

In the layout definition section, if I replace hovermode = 'x' with hovermode = 'x unified' I get this result:

I would like to remove from this menu the first line that contains the information on the x. I honestly don't know where to start, I tried to consult the plotly documentation but I did not get any clue.
What I would get (image manually edited):

A possible alternative would be to improve the appearance of the menu that appears in the first image:

• adding a unique background for the two contours
• adding a colored line for each contour

Version info:

Python  4.7.0
dash    1.12.0
plotly  4.7.0

Answer 1

If this is your desired output:

Then just include:

figure.update_traces(hoverinfo = 'name+z')

And, for both go.Contour , drop the hovertemplate parts:

 #hovertemplate = 'Z1 = %{z: .0f}<extra></extra>',
 .
 .
 #hovertemplate = 'Z2 = %{z: .0f}<extra></extra>',

Plot:

Some important details:

It seems that figure.update_traces(hoverinfo = 'name+z') or similar setups will have noe effect if a hovertemplate has been defined in go.Contour() . At least that is what I've found to be the case. Please let me know if you make any other discoveries after testing this!

Complete code:

# IMPORT
import plotly.graph_objs as go
import plotly.offline as pyo
import numpy as np

# CONSTANTS SET UP
N = 11
x_min = 0
x_max = 10
y_min = 0
y_max = 10
fontsize = 18

# COLORS SET UP
blue = '#6683f3'
orange = '#ff9266'
black = '#212121'

# DEFINE THE MESH GRID
x = np.linspace(x_min, x_max, N)
y = np.linspace(y_min, y_max, N)
XX, YY = np.meshgrid(x, y)

# CALCULATE Z1 AND Z2
Z1 = XX + YY
Z2 = XX - YY

# DEFINE THE TRACES LIST
data = [go.Contour(z = Z1,
                   transpose = True,
                   name = 'Z1',
                   zmin = np.min(Z1),
                   zmax = np.max(Z1) + 1,
                   #hovertemplate = 'Z1 = %{z: .0f}<extra></extra>',
                   contours_coloring = 'lines',
                   showscale = False,
                   showlegend = True,
                   colorscale = [[0, orange], [1, orange]],
                   line_width = 4,
                   ncontours = 20,
                   contours = dict(showlabels = True,
                                   labelformat = '.0f',
                                   labelfont = dict(size = 18))),
        go.Contour(z = Z2,
                   transpose = True,
                   name = 'Z2',
                   zmin = np.min(Z2),
                   zmax = np.max(Z2) + 1,
                  # hovertemplate = 'Z2 = %{z: .0f}<extra></extra>',
                   contours_coloring = 'lines',
                   showscale = False,
                   showlegend = True,
                   colorscale = [[0, blue], [1, blue]],
                   line_width = 4,
                   ncontours = 20,
                   contours = dict(showlabels = True,
                                   labelformat = '.0f',
                                   labelfont = dict(size = fontsize)))]

# DEFINE THE LAYOUT
layout = go.Layout(plot_bgcolor = black,
                   hovermode = 'x unified')

# DEFINE THE FIGURE
figure = go.Figure(data = data,
                   layout = layout)

figure.update_traces(hoverinfo = 'name+z')

figure.update_layout(legend = dict(itemsizing = 'constant',
                                   font = dict(size = fontsize)),
                     hoverlabel = dict(font_size = fontsize))

figure.show()