Dash Plotly 关闭警告/错误

问题描述

我用 Python 创建了一个非常简单的 Dash Plotly 代码。

• 用户拖动一个输入文件（任何带有字符串列名的 excel 文件都可以）。
• 从 x 和 y 轴的下拉列表中选择他需要的列名。
• 出现一个简单的图表。

但是，在用户拖动输入文件之前，我一直遇到这些错误，因为在用户上传任何内容之前，代码会看到“无”。

有什么办法可以让它闭嘴吗？

代码如下：

import base64
import datetime
import io
import plotly.graph_objs as go
import cufflinks as cf

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

import pandas as pd

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

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

colors = {"graphBackground": "#F5F5F5","background": "#ffffff","text": "#000000"}

app.layout = html.Div(
    [
        dcc.Upload(
            id="upload-data",children=html.Div(["Drag and Drop or ",html.A("Select Files")]),style={
                "width": "100%","height": "60px","lineHeight": "60px","borderWidth": "1px","borderStyle": "dashed","borderRadius": "5px","textAlign": "center","margin": "10px",},# Allow multiple files to be uploaded
            multiple=True,),dcc.Dropdown(
            id='x_dropdown',options = [],placeholder="X Axis - Please Select Column"),dcc.Dropdown(
            id='y_dropdown',placeholder="Y Axis - Please Select Column"),dcc.Graph(id="Mygraph"),html.Div(id="output-data-upload"),]
)


@app.callback(Output('Mygraph','figure'),[
Input('upload-data','contents'),Input('upload-data','filename'),Input('x_dropdown','value'),Input('y_dropdown','value')
])



def update_graph(contents,filename,x_dropdown,y_dropdown):
    x = []
    y = []
    if contents:
        contents = contents[0]
        filename = filename[0]
        x_dropdown = str(x_dropdown)
        y_dropdown = str(y_dropdown)
        df = parse_data(contents,filename)
        df = df.set_index(df.columns[0])
        x=df[x_dropdown]
        y=df[y_dropdown]
    fig = go.figure(
        data=[
            go.Bar(
                x=x,y=y)
            ],layout=go.Layout(
            plot_bgcolor=colors["graphBackground"],paper_bgcolor=colors["graphBackground"]
        ))
    return fig


def parse_data(contents,filename):
    content_type,content_string = contents.split(",")

    decoded = base64.b64decode(content_string)
    try:
        if "csv" in filename:
            # Assume that the user uploaded a CSV or TXT file
            df = pd.read_csv(io.StringIO(decoded.decode("utf-8")))
        elif "xls" in filename:
            # Assume that the user uploaded an excel file
            df = pd.read_excel(io.BytesIO(decoded))
        elif "txt" or "tsv" in filename:
            # Assume that the user upl,delimiter = r'\s+'oaded an excel file
            df = pd.read_csv(io.StringIO(decoded.decode("utf-8")),delimiter=r"\s+")
    except Exception as e:
        print(e)
        return html.Div(["There was an error processing this file."])

    return df

@app.callback(
    Output("output-data-upload","children"),[Input("upload-data","contents"),Input("upload-data","filename")],)


def update_table(contents,filename):
    table = html.Div()

    if contents:
        contents = contents[0]
        filename = filename[0]
        df = parse_data(contents,filename)
        table = html.Div(
            [
                html.Hr(),html.H5(filename),html.Hr(),dash_table.DataTable(
                    data=df.to_dict("rows"),columns=[{"name": str(i),"id": str(i)} for i in df.columns],html.Div(""),]
        )

    return table

# update x_dropdown
@app.callback(Output('x_dropdown','options'),[Input('upload-data','filename')])

def update_x_dropdown(contents,filename):
    contents = contents[0]
    filename = filename[0]
    if contents is not None:
        df = parse_data(contents,filename)
        columns = df.columns.values.tolist()
        if df is not None:
            return [ {'label': x,'value': x} for x in columns ]
        else:
            return []
    else:
        return []
    
# update y_dropdown
@app.callback(Output('y_dropdown','filename')])

def update_y_dropdown(contents,'value': x} for x in columns ]
        else:
            return []
    else:
        return []


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

非常感谢！

解决方法

您的想法是正确的：

def update_y_dropdown(contents,filename):
    contents = contents[0]
    filename = filename[0]
    if contents is not None:
        # do stuff

在尝试做任何事情之前，只需让每个回调检查实际值。