如何为多加密货币折线图添加支持单选、多选的下拉选择菜单

最优实现方案基于你已导入的Dash框架完成，无需引入额外依赖，直接复用你已写好的爬虫和数据拉取逻辑，仅需替换静态绘图部分为动态交互逻辑即可，完整实现如下：

完整可运行代码 #

from datetime import datetime, timedelta
from pycoingecko import CoinGeckoAPI
import pandas as pd
import pandas_datareader as pdr
import plotly.graph_objs as go
import requests
import lxml.html as lh
import dash
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output

# 爬取加密货币列表
url = 'https://finance.yahoo.com/cryptocurrencies?count=100&offset=0'
page = requests.get(url)
doc = lh.fromstring(page.content)
tr_elements = doc.xpath('//tr')

col=[]
i=0
# For each row, store each first element (header) and an empty list
for t in tr_elements[0]:
    i+=1
    name=t.text_content()
    col.append((name,[]))

for j in range(1,len(tr_elements)):
    T=tr_elements[j]
    i=0
    for t in T.iterchildren():
        data=t.text_content()
        if i>0:
            try:
                data=int(data)
            except:
                pass
        col[i][1].append(data)
        i+=1

Dict={title:column for (title,column) in col}
df=pd.DataFrame(Dict)
crypto_df = df.set_index('Symbol')

CRYPTOS = []
CURRENCY = 'USD'

for x in crypto_df.index:
    x = x.split('-')[0]
    CRYPTOS.append(x)

# 提前拉取所有加密货币的历史数据，避免每次选择重复请求
def getData(cryptocurrency):
    now = datetime.now()
    current_date = now.strftime("%Y-%m-%d")
    last_year_date = (now - timedelta(days=365)).strftime("%Y-%m-%d")
    start = pd.to_datetime(last_year_date)
    end = pd.to_datetime(current_date)
    data = pdr.get_data_yahoo(f'{cryptocurrency}-{CURRENCY}', start, end)
    return data

crypto_data = {crypto:getData(crypto) for crypto in CRYPTOS}

# 初始化Dash应用
app = dash.Dash(__name__)

# 页面布局
app.layout = html.Div([
    html.H1('加密货币价格走势图表'),
    # 支持多选的下拉菜单
    dcc.Dropdown(
        id='crypto-select',
        options=[{"label": c, "value": c} for c in CRYPTOS],
        value=CRYPTOS[:3], # 默认选中前3个加密货币
        multi=True, # 开启多选模式
        placeholder="请选择要展示的加密货币"
    ),
    # 图表承载组件
    dcc.Graph(id='crypto-graph')
])

# 回调函数：根据选中的加密货币动态生成图表
@app.callback(
    Output('crypto-graph', 'figure'),
    Input('crypto-select', 'value')
)
def update_graph(selected_cryptos):
    # 处理未选中任何币种的情况
    if not selected_cryptos:
        return go.Figure()
    fig = go.Figure()
    # 仅渲染选中的加密货币折线
    for name in selected_cryptos:
        fig.add_trace(
            go.Scatter(
                x = crypto_data[name].index,
                y = crypto_data[name].Close,
                name = name,
            )
        )
    # 保留原有样式配置
    fig.update_layout(
        title = 'Cryptocurrency Price Chart',
        xaxis_title = 'Date',
        yaxis_title = f'Closing price ({CURRENCY})',
        legend_title = 'Cryptocurrencies'
    )
    fig.update_yaxes(type='log', tickprefix='$')
    return fig

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

使用说明 #

运行代码后打开浏览器访问http://127.0.0.1:8050即可使用：

• 单选：直接点击下拉菜单中对应币种即可切换
• 多选：按住Ctrl键点击下拉菜单中对应币种，可同时选中多个币种展示

核心优化点 #

• 复用你原有数据爬取逻辑，所有历史数据仅拉取一次，选择币种时无需重复请求接口，加载速度快
• 完全保留你原有图表的对数坐标轴、美元单位前缀、标题等配置，无需额外调整样式
• 原生支持全量25种加密货币的单选/多选切换，无性能问题

内容的提问来源于stack exchange，提问作者Rubberleg