Plotly Dash实现带多选默认全选下拉框的散点图开发问题

你只需要修改两处核心逻辑即可实现需求：

1. 调整下拉框默认值为全部胶囊ID列表，实现默认全选效果
2. 修改回调中的数据筛选规则，适配多选返回的列表格式数据

核心修改说明 #

• 下拉框的value参数从单个数值2100015改为你提前提取好的全量胶囊ID列表capsuleID_names
• 筛选数据时将==判断替换为pandas的isin()方法，支持匹配列表内的多个ID
• 额外补充空选判断：当用户清空所有选中项时默认展示全部数据，避免图表为空

修改后完整代码 #

import pandas as pd
import plotly.express as px  # (version 4.7.0)
import plotly.graph_objects as go

import dash  # (version 1.12.0) pip install dash
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output

app = dash.Dash(__name__)

df = pd.read_csv("tcd vs rh.csv")
print(df)

capsuleID = df['Capsule_ID'].unique()
print(capsuleID)

capsuleID_names = list(capsuleID)
print(capsuleID_names)

app.layout = html.Div([

    html.H1("Web Application Dashboards with Dash", style={'text-align': 'center'}),

    dcc.Dropdown(id="capsule_select",
                 options=[{"label": cid, "value": cid} for cid in capsuleID_names],
                 multi=True,
                 value=capsuleID_names, # 此处修改为全量ID列表，默认全选
                 style={'width': "40%"}
                 ),

    html.Div([
        dcc.Graph(id="the_graph")
    ]),

])


# -----------------------------------------------------------
@app.callback(
    Output('the_graph', 'figure'),
    [Input('capsule_select', 'value')]
)
def update_graph(capsule_chosen):
    # 空选处理+多选筛选逻辑
    if not capsule_chosen:
        dff = df
    else:
        dff = df[df['Capsule_ID'].isin(capsule_chosen)]  

    scatterplot = px.scatter(
    data_frame=dff,
    x="tcd",
    y="humidity",
              )

    scatterplot.update_traces(textposition='top center')

    return scatterplot


# ------------------------------------------------------------------------------

if __name__ == '__main__':
    app.run_server(debug=True)

内容的提问来源于stack exchange，提问作者haroldchoi