plot Dash热图，链接到2个下拉列表

Question

如何在plotly dash中创建一个应用程序，我想在其中创建一个链接到2下拉列表的热图?下拉列表从Pandas DF中读取' my_dropdown1 '和' my_dropdown2 '。

Answer 1

我认为这种情况的一个很好的例子是在Dash文档:基本回调，Dash应用程序与多个输入。https://dash.plotly.com/basic-callbacks

这个例子有2个下拉框和2个单选按钮。这是一个散点图。您可以重新格式化此示例以创建热图并使用两个下拉列表。

import dash
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output
import plotly.express as px
import pandas as pd
app = dash.Dash(__name__)
df = pd.read_csv('https://plotly.github.io/datasets/country_indicators.csv')
available_indicators = df['Indicator Name'].unique()
app.layout = html.Div([
html.Div([
html.Div([
dcc.Dropdown(
id='xaxis-column',
options=[{'label': i, 'value': i} for i in available_indicators],
value='Fertility rate, total (births per woman)'
),
dcc.RadioItems(
id='xaxis-type',
options=[{'label': i, 'value': i} for i in ['Linear', 'Log']],
value='Linear',
labelStyle={'display': 'inline-block'}
)
], style={'width': '48%', 'display': 'inline-block'}),
html.Div([
dcc.Dropdown(
id='yaxis-column',
options=[{'label': i, 'value': i} for i in available_indicators],
value='Life expectancy at birth, total (years)'
),
dcc.RadioItems(
id='yaxis-type',
options=[{'label': i, 'value': i} for i in ['Linear', 'Log']],
value='Linear',
labelStyle={'display': 'inline-block'}
)
], style={'width': '48%', 'float': 'right', 'display': 'inline-block'})
]),
dcc.Graph(id='indicator-graphic'),
dcc.Slider(
id='year--slider',
min=df['Year'].min(),
max=df['Year'].max(),
value=df['Year'].max(),
marks={str(year): str(year) for year in df['Year'].unique()},
step=None
)
])

@app.callback(
Output('indicator-graphic', 'figure'),
Input('xaxis-column', 'value'),
Input('yaxis-column', 'value'),
Input('xaxis-type', 'value'),
Input('yaxis-type', 'value'),
Input('year--slider', 'value'))
def update_graph(xaxis_column_name, yaxis_column_name,
xaxis_type, yaxis_type,
year_value):
dff = df[df['Year'] == year_value]
fig = px.scatter(x=dff[dff['Indicator Name'] == xaxis_column_name]['Value'],
y=dff[dff['Indicator Name'] == yaxis_column_name]['Value'],
hover_name=dff[dff['Indicator Name'] == yaxis_column_name]['Country Name'])
fig.update_layout(margin={'l': 40, 'b': 40, 't': 10, 'r': 0}, hovermode='closest')
fig.update_xaxes(title=xaxis_column_name,
type='linear' if xaxis_type == 'Linear' else 'log')
fig.update_yaxes(title=yaxis_column_name,
type='linear' if yaxis_type == 'Linear' else 'log')
return fig

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