How to plot a 3D surface from X,Y,Z array in Plotly?

Question

I try to understand how to plot a 3D surace from X,Y,Z real data array. So, I've found a good sample of Plotlu 3D surface plotting:

import plotly.graph_objects as go

import pandas as pd

# Read data from a csv
z_data = pd.read_csv('https://raw.githubusercontent.com/plotly/datasets/master/api_docs/mt_bruno_elevation.csv')

fig = go.Figure(data=[go.Surface(z=z_data.values)])

fig.update_layout(title='Mt Bruno Elevation', autosize=False,
                  width=500, height=500,
                  margin=dict(l=65, r=50, b=65, t=90))

fig.show()

But, mt_bruno_elevation.csv data is a bit confusing for me. I don't understand what exactly data represents in csv and how to build something similar if I have an X,Y,Z array of my real data.

Answer 1

The simplest equation of a surface is of the form z=f(x,y). As far as I can understand, in this example, z-data is a 2D array. Take a look at below example;

 z-data = [ 
[ 0.1, 0.2, 0.3, 0.4 ],
[ 0.5, 0.6, 0.7, 0.8 ],
[ 0.9, 1.0, 1.1, 1.2 ],
[ 1.3, 1.4, 1.5, 1.6 ]
]

This is a z-matrix. That is those numbers are the values of y-axis for different z and x . Now the question is, what z and x are.

The first element of z-data ( [ 0.1, 0.2, 0.3, 0.4 ] ) is for constant z=0 and different values of x . So (x,y,z) for the first value (0.1) equals to (0,0.1,0). For second value (0.2) is (1,0.2,0) and so on.

The second element of z-data ( [ 0.5, 0.6, 0.7, 0.8 ] ) is for constant z=1 and different values of x . So (x,y,z) for the first value (0.5) equals to (0,0.5,1). For second value (0.6) is (1,0.6,1) and so on.

Helpful links: Link 1 Link 2 Link 3