Tracer des tracés de couleurs dans Matplotlib

import plotly.express as px

px.colors.sequential.ice

['rgb(3, 5, 18)',
 'rgb(25, 25, 51)',
 'rgb(44, 42, 87)',
 'rgb(58, 60, 125)',
 'rgb(62, 83, 160)',
 'rgb(62, 109, 178)',
 'rgb(72, 134, 187)',
 'rgb(89, 159, 196)',
 'rgb(114, 184, 205)',
 'rgb(149, 207, 216)',
 'rgb(192, 229, 232)',
 'rgb(234, 252, 253)']

my_cmap = matplotlib.colors.listedcolormap(px.colors.sequential.ice, name='my_colormap_name')

ValueError: Invalid RGBA argument: 'rgb(3, 5, 18)'

import plotly.express as px
import matplotlib.pyplot as plt
import matplotlib.colors as mcolors

samples = 20
ice = px.colors.sample_colorscale(px.colors.sequential.ice, samples)
rgb = [px.colors.unconvert_from_rgb_255(px.colors.unlabel_rgb(c)) for c in ice]

cmap = mcolors.listedcolormap(rgb, name='ice', n=samples)

import numpy as np

gradient = np.linspace(0, 1, 256)
gradient = np.vstack((gradient, gradient))
plt.imshow(gradient, aspect='auto', cmap=cmap)
plt.show()