使用下拉菜单更改堆叠条形图颜色

花卉

我正在尝试创建一个堆积条形图，然后通过下拉值更改它的颜色。下面是我的示例代码：

import pandas as pd
import numpy as np
import plotly.express as px
import dash
from dash import html
from dash import dcc
from dash.dependencies import Input, Output, State
import dash_bootstrap_components as dbc

app = dash.Dash(__name__,external_stylesheets=[dbc.themes.LUX]) # You can change external_stylesheets
    # Make the layout with two tabs
    
    colorscales = dir(px.colors.qualitative)
    df = px.data.medals_long()
    
    app.layout = html.Div([
        dbc.Row([html.H6('Color Palette',className='text-left'),
                dcc.Dropdown(id='color_range',placeholder="Color", # Dropdown for heatmap color
                    options=colorscales, 
                    value='aliceblue',
                    multi=False,
                    disabled=False,
                    clearable=True,
                    searchable=True),  
        dcc.Graph(id='bar_chart',figure={},style={'height':500,'width':'auto'})
        ])
    ])
    
    @app.callback(Output('bar_chart','figure'),
                 [Input('color_range', 'value')]) 
    
    def update_color(color_range):
        fig = px.bar(df, x="medal", y="count", color="nation", text="nation",
                     color_discrete_sequence = color_range)
        return fig
    
    if __name__ == "__main__":
        app.run_server(debug=False)

但它引发了一个错误，上面写着：

ValueError: 
    Invalid value of type 'builtins.str' received for the 'color' property of bar.marker
        Received value: 'a'

    The 'color' property is a color and may be specified as:
      - A hex string (e.g. '#ff0000')
      - An rgb/rgba string (e.g. 'rgb(255,0,0)')
      - An hsl/hsla string (e.g. 'hsl(0,100%,50%)')
      - An hsv/hsva string (e.g. 'hsv(0,100%,100%)')
      - A named CSS color:
            aliceblue, antiquewhite, aqua, aquamarine, azure,

我尝试从colorscales = dir(px.colors.qualitative)to更改为colorscales = px.colors.named_colorscales()，然后更改color_discrete_sequence为，color_continuous_scale但没有成功。它没有引发错误，但颜色没有改变。

谢谢你。

r-初学者

修改的是下拉默认应该选择一个定性的颜色名称。并且条形图颜色规范需要写在表格中px.colors.qualitative.G10。

app.layout = html.Div([
    dbc.Row([html.H6('Color Palette',className='text-left'),
            dcc.Dropdown(id='color_range',placeholder="Color", # Dropdown for heatmap color
                options=colorscales, 
                value='Plotly',# update
                multi=False,
                disabled=False,
                clearable=True,
                searchable=True),  
    dcc.Graph(id='bar_chart',figure={},style={'height':500,'width':'auto'})
    ])
])

def update_color(color_range):
    df = px.data.medals_long() # update
    fig = px.bar(df, x="medal", y="count", color="nation", text="nation",
                     color_discrete_sequence = eval('px.colors.qualitative.{}'.format(color_range))) # update
    return fig