Plotly: How to set individual color for each y error bar using go.Figure and go.Scatter?

Question

I'm using Plotly to create a scatter plot with error bars in Python. But, I'm unable to apply a color code to error bars. In the Plotly documentation, error bar color will take only a 'single color', and thus it fails when I add color list. How could I workaround this?

I've provided a sample code, and the plot I get. If I remove the # in the color command in error dict, the code will error out.

import numpy as np
import plotly.graph_objects as go

x_data = ['10 days', '20 days', '30 days']
y_data = [0.5, 0.8, 0.4]
err_y_data = [0.1, 0.2, 0.05]

colors = ['rgba(93, 164, 214, 0.7)', 'rgba(255, 144, 14, 0.7)', 'rgba(44, 160, 101, 0.7)']

fig = go.Figure()

fig.add_trace(go.Scatter(
    x=x_data,
    y=y_data,
    text=np.round(y_data, 1),
    mode='markers+text',
    textposition='top center',
    error_y=dict(
        type='data',
        #color = colors,
        array=err_y_data,
        visible=True),
    marker=dict(color=colors, size=12)
))

fig.show()

I get the following plot,

However, I'll ideally want the error bars to be the same color as the respective markers. I cannot use plotly express, as I'll have to create subplots, and need control.

Answer 1

This is no problem at all as long as you've got your y_error data available like you do here err_y_data = [0.1, 0.2, 0.05]. You can't add several colors to the error bars of one trace, but you can add one trace per error bar, using, among other things:

for i, bar in enumerate(err_y_data):
    fig.add_trace(go.Scatter(
                    x=[x_data[i]],
                    y=[y_data[i]],
                    error_y=dict( type='data',color = colors[i],array=[bar],visible=True),
                    marker=dict(color='rgba(0,0,0,0)', size=12),
                    showlegend=False
                ))

Plot:

Complete code:

import numpy as np
import plotly.graph_objects as go

x_data = ['10 days', '20 days', '30 days']
y_data = [0.5, 0.8, 0.4]
err_y_data = [0.1, 0.2, 0.05]

colors = ['rgba(93, 164, 214, 0.7)', 'rgba(255, 144, 14, 0.7)', 'rgba(44, 160, 101, 0.7)']

fig = go.Figure()

fig.add_trace(go.Scatter(x=x_data, y=y_data,
                            text=np.round(y_data, 1),
                            mode='markers+text',
                            textposition='top center',
                        #     error_y=dict(
                        #         type='data',
                        #         #color = colors,
                        #         array=err_y_data,
                        #         visible=True),
                            marker=dict(color=colors, size=12),
                            showlegend=False
            ))

for i, bar in enumerate(err_y_data):
    fig.add_trace(go.Scatter(
                    x=[x_data[i]],
                    y=[y_data[i]],
                   # text=np.round(y_data, 1),
                    mode='markers+text',
                    textposition='top center',
                    error_y=dict(
                        type='data',
                        color = colors[i],
                        array=[bar],
                        visible=True),
                    marker=dict(color='rgba(0,0,0,0)', size=12),
                    showlegend=False
                ))

fig.show()