Plotly Dash:仅当Pandas DataFrame中存在特定数据时才呈现图形

import dash
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output
import pandas as pd
import plotly.express as px

app = dash.Dash(__name__)

df = pd.read_csv('data.csv')  # 假设数据保存在data.csv文件中

app.layout = html.Div([
    dcc.Graph(id='graph')
])

@app.callback(
    Output('graph', 'figure'),
    [Input('dropdown', 'value')]  # 假设使用下拉菜单选择特定数据
)
def update_graph(selected_data):
    filtered_df = df[df['column'] == selected_data]  # 根据特定数据筛选DataFrame
    fig = px.scatter(filtered_df, x='x', y='y')  # 使用Plotly Express创建散点图
    return fig

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