How to overlay two quiver plots

📊 Plotly Python
1

Hi all,

I have just started using Plotly and by looking in this Forum I have not seen a similar question asked so I hope I am not duplicating a question.

Basically, I have two vectorial fields, which I would like to plot, with different colors, on the same graphs. Is anybody able to point me towards some documentation that can help me with this question?

Thank you very much,
P

2

HI @PolTricerri welcome to th forums. It depends a bit on your data and how you want the final graph to look like but here you can find some inforamtion:

A basic example for overlaying two quiver plots:

import plotly.figure_factory as ff
import numpy as np

scaleratio=0.8
scale=0.4

# create data
x,y = np.meshgrid(np.arange(0, 2, .2), np.arange(0, 2, .2))
u = np.cos(x)*y
v = np.sin(x)*y

# base figure (including first trace)
fig = ff.create_quiver(x, y, u, v, scale=scale, scaleratio=scaleratio)

# create second figure object, extract trace --> .data[0]
trace2 = ff.create_quiver(x, y, v, u, scale=scale, scaleratio=scaleratio).data[0]

# add trace to figure
fig.add_traces(trace2)

# set heigth and width and show figure
fig.update_layout(height=500, width=500)
fig.show()

creates:
newplot

mrep quiverplot

3

@PolTricerri You can control the plot aesthetics by setting for each quiver its own scale, arrow_scale, angle and line_width. A global settings for these parameters can lead to awful plots.

import plotly.graph_objects as go
import plotly.figure_factory as ff
from numpy import sin, cos,  pi
import numpy as np
x, y = np.mgrid[0:2:16j,0:2:16j]    
u = sin(x*pi) * cos(y*pi) 
v = cos(x*pi) * sin(y*pi) 

fig = ff.create_quiver(x, y, u, v,
                       scale=0.15,
                       arrow_scale=.4,
                       angle=pi/15,
                       name='quiver1',
                       line=dict(width=1.15, color='#8f180b'))
fig.update_layout(width=500, height=500)
x,y = np.meshgrid(np.arange(0, 2, .2),
                  np.arange(0, 2, .25))
z = x*np.exp(-x**2 - y**2)
v, u = np.gradient(z, .2, .2)

# Second quiver
fig.add_trace(ff.create_quiver(x, y, u, v,
                       scale=.25,
                       arrow_scale=.3,
                        angle=pi/15,        
                       name='quiver2',
                       line_width=1.15).data[0])

# Add an equilibrium point of the second vector field to figure
fig.add_trace(go.Scatter(x=[.75], y=[0,0],
                    mode='markers',
                    marker_size=8, marker_color='red',
                    name='equilibrium'))