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Feature request: 2D "cone" plots #4748

@vidarsko

Description

@vidarsko

First of all, thank you for such an amazing plotting library.

The 3D cone plot function is amazing. Creating a fast, informative and responsive presentation of 3D vector fields.

image

My feature request is a similar function for two dimensions, taking x- and y-coordinates, and the vector components as input and creates a similar plot. I have made my own version of this function with plotly, which produces plots like this:

image

which works, but it is very slow. The relevant code snippets used to produce the figure above is given below:

def plot_vector_field(x,y,u,v):
    def get_colors(values, colorscale='Viridis'):
                        colorscale = pc.get_colorscale(colorscale)
                        unique_magnitudes = np.unique(values)
                        color_map = {val: pc.sample_colorscale(colorscale, val)[0] for val in unique_magnitudes}
                        return np.vectorize(color_map.get)(values)

    def plot_triangle(fig, position,direction,size,color):
                        x = [position[0]+direction[0]*size/2, 
                                position[0]-direction[0]*size/3 + direction[1]*size/4, 
                                position[0]-direction[0]*size/3 - direction[1]*size/4]
                        y = [position[1]+direction[1]*size/2, 
                                position[1]-direction[1]*size/3 - direction[0]*size/4, 
                                position[1]-direction[1]*size/3 + direction[0]*size/4]

                        fig.add_trace(go.Scatter(
                                                x=x,
                                                y=y,
                                                fill='toself',
                                                mode='lines', 
                                                line=dict(color='rgba(0,0,0,0)'),
                                                fillcolor=color,
                                                showlegend=False,
                                                name=''
                                            ))
        
        magnitude = np.sqrt(u**2 + v**2)
        magnitude_normalized = magnitude/np.max(magnitude)
        
        colors = get_colors(magnitude_normalized, colorscale='viridis')
        
        angle = np.arctan2(v, u)
        
        direction = np.array([np.cos(angle), np.sin(angle)]).T

        fig = go.Figure()

        for i in range(len(x)):
                            plot_triangle(fig, 
                                                position=[x[i],y[i]], 
                                                direction=direction[i], 
                                                size=1.3*magnitude_normalized[i], 
                                                color=colors[i])
        return fig

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