如何返回由 2 个下拉列表更新的数据表作为 Plotly Python 中的输入

Posted 2023-02-22

【中文标题】如何返回由 2 个下拉列表更新的数据表作为 Plotly Python 中的输入

【英文标题】：How to return a datatable updated by 2 dropdowns as inputs in Plotly Python

【发布时间】：2020-06-18 18:22:57

【问题描述】：

如标题所示，我正在创建一个仅包含数据表的绘图仪表板。将有 2 个下拉菜单作为输入，数据表将根据下拉菜单更新。如何设置布局和回调？

import pandas as pd
import dash
import dash_core_components as dcc
import dash_html_components as html
import dash_table as dt
from dash.dependencies import Input, Output, State

df = pd.read_csv(data, header=0, encoding = 'utf8')

app = dash.Dash()
application = app.server

dropdown = html.Div([html.Label('district'),
             dcc.Dropdown(id='dropdown_d',
                          options=['label': i, 'value': i for i in df["district"].unique()], value='none'),
             html.Label('address'),
             dcc.Dropdown(id='dropdown_a',
                          options=['label': i, 'value': i for i in df["address"].unique()], value='none')])

final_table = html.Div([dash_table.DataTable(id="final_table")])

app.layout = html.Div([dropdown, final_table])

@app.callback(Output('final_table', 'data'),
          [Input('dropdown_d', 'value'),
           ])

def update_table(selected_value):
    df = pd.read_csv(data, header=0, encoding = 'utf8')
    df_updated = df[df["district"] == selected_value]
    columns = ['name': i, 'id': i for i in df_updated.columns]
    data = df.to_dict('records')
    return columns, data

if __name__ == "__main__":
    app.run_server(debug=True, port=8055)

这是我能到达的最远的地方。上面的代码只是试图从 1 个下拉值更新数据表，但我的目标是更新 2 个下拉值。

非常感谢任何帮助。 如果需要数据文件，这里是data的链接。

【参考方案1】：

这里是工作代码的sn-p，我已经添加了cmets来澄清，

import pandas as pd
import dash
import dash_core_components as dcc
import dash_html_components as html
import dash_table as dt
from dash.dependencies import Input, Output, State

df = pd.read_csv("https://elartedm.com/wp-content/uploads/2020/03/data_hk.csv", header=0, encoding = 'utf8')

app = dash.Dash()
application = app.server

dropdown = html.Div([
    html.Label('district'),
    dcc.Dropdown(id='dropdown_d1', options=['label': i, 'value': i for i in df["District"].unique()], value=None),
    html.Label('address'),
    dcc.Dropdown(id='dropdown_d2', options=[], value=None)
])


#its better to have a Div here so that you can update the entire div in the callback and add the necessary properties in the callback
final_table = html.Div(id="final_table")

app.layout = html.Div([dropdown, final_table])


#callback to update second dropdown based on first dropdown
#This callback is used to update the second dropdown based on the value selected in the first dropdown so that its dynamically updated (this is a good  practice rather than having a static list of options).
@app.callback(Output('dropdown_d2', 'options'),
          [
            Input('dropdown_d1', 'value'),
          ])
def update_dropdown_2(d1):
    print(d1)
    if(d1 != None):
        df_filtered = df[(df["District"]==d1)]
        return ['label': i, 'value': i for i in df_filtered["Address"].unique()]
    else:
        return []


#this callback to update the final table should be based on both the input dropdown values, so the input parameters are two dropdown_d1, dropdown_d2
#based on these values filter the dataframe and update the table
#since dataframe is a global declaration you don't need to again consume it here.
@app.callback(Output('final_table', 'children'),
          [
            Input('dropdown_d1', 'value'),
            Input('dropdown_d2', 'value'),
          ])
def update_table(d1, d2):

    if(d1 != None and d2 != None):
        df_filtered = df[(df["District"]==d1) & (df["Address"]==d2)]

        return [dt.DataTable(
            id='table',
            columns=["name": i, "id": i for i in df_filtered.columns],
            data=df_filtered.to_dict('records'),
        )]
    else:
        print("none")
        return []


if __name__ == "__main__":
    app.run_server(debug=True, port=8055)

希望对你有帮助。

【讨论】：

它就像魔术一样，非常感谢@Lawliet！我现在正在尝试理解它，并且会在一段时间内回来。

更新：再次感谢您的回答。我回来了，请教一下，现在final_table这里没有给孩子起名字，但是为什么系统有时候会报错说没有指定孩子呢？

@yts61 我不太确定这个错误，我可能在这里遗漏了一些极端情况，如果你能让我知道如何重新创建问题，我可以尝试找出是什么导致错误。