Plotly Dash：为什么我的数字无法通过多个下拉选项显示？

Question

我正在使用 dash 和 plotly 构建一个简单的 python 仪表板。我也是 python 的新手（可能很明显！），我很高兴任何/所有更正。我想从预先确定的 CSV 文件中绘制时间序列数据。我添加了一个下拉选择框，我想用它来绘制多个不同的列。样本数据："TOA5","HE605_RV50_GAF","CR6","7225","CR6.Std.07","CPU:BiSP5_GAF_v2d.CR6","51755","SensorStats""TIMESTAMP","RECORD","BattV_Min","BattV_Avg","PTemp_C_Avg","SensorRel_Min(1)","SensorRel_Min(2)","SensorRel_Min(3)","SensorRel_Min(4)","SensorRel_Min(5)","SensorRel_Max(1)","SensorRel_Max(2)","SensorRel_Max(3)","SensorRel_Max(4)","SensorRel_Max(5)""TS","RN","Volts","Volts","Deg C","","","","","","","","","","""","","Min","Avg","Avg","Min","Min","Min","Min","Min","Max","Max","Max","Max","Max""2019-09-30 11:15:00",0,12.68219,12.74209,"NAN","NAN","NAN","NAN","NAN","NAN","NAN","NAN","NAN","NAN","NAN""2019-09-30 11:30:00",1,12.68466,12.73777,31.26331,-2.498894,-2.38887,-8.497528,-2.963989,-20.42339,41.51585,28.41309,88.98283,27.27819,17.98986"2019-09-30 11:45:00",2,12.69364,12.74584,31.43891,-3.490456,-2.856804,-8.770081,-3.879868,-22.69171,42.27676,30.53723,89.47752,34.25191,23.92586"2019-09-30 12:00:00",3,12.69078,12.74522,31.38461,-3.290047,-2.973389,-8.69928,-3.295074,-21.88254,42.72508,29.91062,83.36012,27.9931,22.6571"2019-09-30 12:15:00",4,12.6914,12.74376,31.2449,-2.899231,-2.392128,-10.01413,-2.996033,-23.22171,42.97162,29.20943,106.1204,35.93995,41.74426我的 python(3.7) 代码是：import dashimport dash_core_components as dccimport dash_html_components as htmlfrom dash.dependencies import Input, Outputimport pandas as pdimport plotly.graph_objects as go# Load external stylesheetsexternal_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']app = dash.Dash(__name__, external_stylesheets=external_stylesheets)    )  ])该图的初始渲染看起来不错，因为这是运行后出现的python3 app.py：

Answer 1

问题是下拉列表返回多个变量的列表（如您设置的那样multi=True），而您的回调旨在仅绘制一个变量。

为了绘制多个变量，您需要遍历选定的变量列表（即通过selectedVariable2您的代码）并将相应的轨迹添加到图中。

您还应该确保下拉列表是用列表而不是字符串初始化的（即您应该value="RECORD"用value=["RECORD"].

我在下面包括了一个例子。

import pandas as pd

import dash

import dash_core_components as dcc

import dash_html_components as html

from dash.dependencies import Input, Output

import plotly.graph_objects as go

# Load external stylesheets

external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']

app = dash.Dash(__name__, external_stylesheets=external_stylesheets)

# Create a sample ataset

df = pd.DataFrame({"TIMESTAMP": ["2019-09-30 11:15:00", "2019-09-30 11:30:00", "2019-09-30 11:45:00", "2019-09-30 12:00:00", "2019-09-30 12:15:00"],

                   "RECORD": [0, 1, 2, 3, 4],

                   "SensorRel_Min(2)": [12.68219, 12.68466, 12.69364, 12.69078, 12.6914],

                   "SensorRel_Min(3)": [14.74209, 13.73777, 10.74584, 9.74522, 16.74376]})

# Define dropdown options

opts = [{'label': k, 'value': k} for k in list(df.columns.values)[1:]]

# Create a Dash layout

app.layout = html.Div(children=[

    html.H1(children='Testing dashboard v01'),

    html.Div(children='''

        Select variable to plot below.

    '''),

    html.Div(children='''

        Select variables to add to plot below.

    '''),

    dcc.Dropdown(

        id='multiVariableDropdown',

        options=opts,

        value=['RECORD'],

        multi=True

    ),

    dcc.Graph(

        id='plot2'

    )

])

# Add callback functions

## For plot 2

@app.callback(Output('plot2', 'figure'),

             [Input('multiVariableDropdown', 'value')])

def update_graph(selectedVariable2):

    traces = []

    for var in selectedVariable2:

        traces.append(go.Scatter(x=df['TIMESTAMP'],

                                 y=df[var],

                                 name=var))

    fig2 = go.Figure(data=traces)

    return fig2

if __name__ == '__main__':

    app.run_server(debug=True)

Answer 2

尝试使用print()对其进行调试。如下所示，这样您就可以在每次从下拉列表中添加/删除内容时看到发送到输出组件的内容。希望能帮助到你！

def update_graph(selectedVariable2):

    trace_finalPlot2 = go.Scatter(

                            x=df['TIMESTAMP'],

                            y=df[selectedVariable2],

                            name=str(selectedVariable2))

    fig2 = go.Figure(data=trace_finalPlot2)

    print(df[selectedVariable2])

    return fig2