How to plot density of lines with plotly

Question

Let's say I have a set lines (y vs. x) that are the result of a random process.

I am looking for a visualization that shows the spread of the lines.

Concretely I am looking to get an e.g. transparency-graded filled region where the opacity corresponds to the height of the histogram at that point.

Somewhat like the plotly "Filled Lines" example, except that I am not looking for hard borders to the area filled but a gradual phasing out using transparency.

One example similar to what I am looking to realize is shown in on this blog:

I would like to plot different sets of lines (e.g. different experimental conditons) on the same plot in different colours to visually compare their results.

Answer 1

Since you're specifically asking for Plotly, one approach could be to visually represent all your results from your random process with an indiviudal line and a certain opacity.

Plot:

Code:

# imports
from plotly.subplots import make_subplots
import plotly.graph_objs as go
import pandas as pd
import numpy as np

# random data
np.random.seed(123)
frame_rows = 50
frame_cols = 500
frame_columns = ['V_'+str(e) for e in list(range(frame_cols+1))]
df=pd.DataFrame()

for col in frame_columns:
    df[col]=np.sin(np.arange(0,frame_rows/10, 0.1)*np.random.uniform(low=0.85, high=0.99))

# plotly figure
fig=go.Figure()
for i in range(1, frame_cols):
        #print(str(i))
        fig.add_trace(go.Scatter(x=df.index,
                                 y=df[df.columns[i]].values,
                                 showlegend=False,           # hides trace name from legend
                                 hoverinfo='skip',           # turns off hoverinfo
                                 name = None,
                                 mode = 'lines',
                                 line_color='black',
                                 opacity = 0.008
                                )
                     )

# add mean of all rows to the plot
df_mean=df.mean(axis=1).to_frame()
df_mean.columns=['mean']
# show mean
fig.add_trace(go.Scatter(x=df_mean.index, y=df_mean['mean'].values,
                          name='mean lines',
                          line_color='red',
                          line=dict(width=2),
                          mode='lines')
             )
        
fig.show()