Plotly Dash 下拉菜单 python

Question

我想添加一个下拉菜单以仅显示一个数字。 我的意思是，如果我是 select 图，破折号必须只显示图，如果我是 select 图 2，则破折号必须显示图 2。这可能吗？ 我的代码是一个例子，我有 500 多个无花果。

import dash
import dash_core_components as dcc
import dash_html_components as html
import plotly.graph_objects as go # or plotly.express as px

fig = go.Figure()
fig2 = go.Figure()
fig.add_trace(go.Scatter(y=[4, 2, 1], mode="lines"))
fig2.add_trace(go.Bar(y=[2, 1, 3]))

figs = [fig, fig2]
div = []
for item in figs:
    div.append(dcc.Graph(figure=item))

app = dash.Dash()
app.layout = html.Div(div)
"""
add a dropdown to show only one fig
"""


app.run_server(debug=True, use_reloader=False)

Answer 1

对的，这是可能的。

首先，您需要创建包含图形名称/文件名或您希望的标识符的下拉列表，只需为选项参数保留{'label': x, 'value': x}结构。 label是您将在下拉列表中看到的内容，并且value将传递给回调（如下所示）。

fig_names = ['fig1', 'fig2']
fig_dropdown = html.Div([
    dcc.Dropdown(
        id='fig_dropdown',
        options=[{'label': x, 'value': x} for x in fig_names],
        value=None
    )])

接下来，您需要一个空白 div（带有id ），其中 plot 将出现：

fig_plot = html.Div(id='fig_plot')

现在创建一个回调。 当id='fig_dropdown'的输入发生变化时， value参数将被传递给update_output function。 这个 function 的 output 将被传递给id='fig_plot' div 的children参数。

@app.callback(
dash.dependencies.Output('fig_plot', 'children'),
[dash.dependencies.Input('fig_dropdown', 'value')])
def update_output(fig_name):
    return name_to_figure(fig_name)

name_to_figure(fig_name) function 返回一个dcc.Graph()对象，其中包含您的图形，具体取决于下拉列表的fig_name值。

完整示例：

import dash
import dash_core_components as dcc
import dash_html_components as html
import plotly.graph_objects as go # or plotly.express as px


app = dash.Dash()

fig_names = ['fig1', 'fig2']
fig_dropdown = html.Div([
    dcc.Dropdown(
        id='fig_dropdown',
        options=[{'label': x, 'value': x} for x in fig_names],
        value=None
    )])
fig_plot = html.Div(id='fig_plot')
app.layout = html.Div([fig_dropdown, fig_plot])

@app.callback(
dash.dependencies.Output('fig_plot', 'children'),
[dash.dependencies.Input('fig_dropdown', 'value')])
def update_output(fig_name):
    return name_to_figure(fig_name)

def name_to_figure(fig_name):
    figure = go.Figure()
    if fig_name == 'fig1':
        figure.add_trace(go.Scatter(y=[4, 2, 1]))
    elif fig_name == 'fig2': 
        figure.add_trace(go.Bar(y=[2, 1, 3]))
    return dcc.Graph(figure=figure)

app.run_server(debug=True, use_reloader=False)

Answer 2

如果您在下拉框中有很多无花果可供选择，则可能需要对代码进行以下更改才能实现：

@app.callback(Output('fig_plot', 'figure'), [Input('fig_dropdown', 'value')])
def cb(plot_type):
    plot_type = plot_type if plot_type else 'fig1'
    df_year = head_db.copy()
    if plot_type:
        return px.bar(df_year, x='Week #', y=str(plot_type), color='Name')

Answer 3

#Libraries/Imports
from dash import Dash, html, dcc, Input, Output
import plotly.graph_objects as go

fig = go.Figure()
fig2 = go.Figure()
fig.add_trace(go.Scatter(y=[4, 2, 1], mode="lines"))
fig2.add_trace(go.Bar(y=2, 1, 3]))

figs = ['fig', 'fig2']

#Your HTML to display the graph
#Disables the multiple dropdown values attributes
app.layout = html.Div([
html.Div(children=[
     html.label('Dropdown'), 
     dcc.Dropdown(id='dropdown', options=(figs), multi=False
     html.div(id='show-my-graph')
    ])
])

#Your callback; is used to display the graph when the dropdown values are selected or updated
@app.callback(
     Output(component_id='show-my-graph'), component_property='children'),
     Input(component_id='dropdown', component_property='value')
)

 #Defines the Function used to display the graph when an option is selected or updated
def update_graph(dropdown_value):
     "Returns the appropriate graph component to display when a dropdown is selected or updated"
     if(dropdown_value == 'fig'): 
          ret_val = dcc.Graph(id='scatter-plot-graph', figure=fig)
          return ret_val 

     if (dropdown_value == 'fig2'):
          ret_val = dcc.Graph(id='bar-graph', figure=fig2)
          return ret_val

app.run_server(debug=True, use_reloader=False)