plotly python change y-axis values ​to your own - python-3.x

Question

A graph of random values ​​is plotted. It is necessary to change the values ​​of the Y axis to others.
xg = np.random.rand(100, 1200)
fig = px.imshow(xg, aspect="auto",color_continuous_scale='ice')
fig.show()
values ​​to be changed
y1=np.arange(100)*0.5
y2=np.arange(100)*5
Thanks!

Answer 1

100 ticks on the yaxis is too many! Have gone with 10
simple case of defining where you want ticks in the range of values (100) and text you want to display again domain value https://plotly.com/python/tick-formatting/#tickmode--array
the multiplications are equivalent to your requirements, just generating arrays of appropriate length (ten ticks)
import numpy as np
import plotly.express as px
xg = np.random.rand(100, 1200)
fig = px.imshow(xg, aspect="auto",color_continuous_scale='ice')
# y1
fig.update_layout(yaxis={"tickmode":"array","tickvals":np.arange(10)*10, "ticktext":np.arange(10)*5}).show()
# y2
fig.update_layout(yaxis={"tickmode":"array","tickvals":np.arange(10)*10, "ticktext":np.arange(10)*50}).show()
supplementary - show both y-axis
as per comment you can use documented approach https://plotly.com/python/multiple-axes/#multiple-axes
you do require a trace per axis hence creation of two traces and modification of second trace to use y2
setting second trace to "visible":False does not work. So there are two identical traces on top of each other
import numpy as np
import plotly.express as px
xg = np.random.rand(100, 1200)
fig = px.imshow(xg, aspect="auto", color_continuous_scale="ice").add_traces(
px.imshow(xg, aspect="auto", color_continuous_scale="ice")
.update_traces(yaxis="y2")
.data
)
fig.update_layout(
xaxis={"domain": [0.05, 1]},
yaxis={
"tickmode": "array",
"tickvals": np.arange(10) * 10,
"ticktext": np.arange(10) * 50,
},
yaxis2={
"tickmode": "array",
"tickvals": np.arange(10) * 10,
"ticktext": np.arange(10) * 5,
"anchor": "free",
"position": 0,
"autorange": "reversed",
},
).show()