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pythonplotlydashboard

only list-like objects are allowed to be passed to isin(), you passed a [str]

I am trying to create dashboard by using the plotly python. Require to create dropdown for date selection for the pie chart. All the data are come from a .csv file.

Expectation: The data displayed in the pie chart are based on the date selected.

Data:
enter image description here

Code:

date_category = list(df['Date'].unique())

app.layout = ...,

        dcc.Dropdown(id='date_drdn', multi=False, value= ['02/01/2022'], 
                      options = [{'label':x, 'value':x} 
                                for x in date_category]
                      ),
                     
        dcc.Graph(id='pie-fig', figure={})

@app.callback(  
      Output('pie-fig', 'figure'),
      Input('date_drdn', 'value'))


def update_graph(selection):
 
      dff = df[df['Date'].isin(selection)]      
      fig = px.pie(dff, values='Transactions', names='Product', color_discrete_sequence=px.colors.sequential.RdBu)
      fig.update_traces(textinfo= "label+value+percent").update_layout(title_x=0.5)
      return fig

However, it keep on showing the error message when select the date.
Error message:"only list-like objects are allowed to be passed to isin(), you passed a [str]"

And the data is not display based on the date selected.

Does anyone know why and how to solve it?

Solution

  • If the return value of the dropdown allows multiple selections, it will be in list format and isin effect. Since the expected pie chart is a single selection of date and time, the list format is not needed as an initial value. At the same time, the return value of the callback will be a single date and time data for conditional extraction.

    date_category = list(df['Date'].unique())

from dash import Dash, dcc, html, Input, Output
import plotly.express as px
#from jupyter_dash import JupyterDash

app = Dash(__name__)
#app = JupyterDash(__name__)

app.layout = html.Div([
    html.H3('Daily Graph'),
    dcc.Dropdown(id='date_drdn',
                 multi=False,
                 value= '02/01/2022',
                 options = [{'label':x, 'value':x} for x in date_category]
                ),
                     
        dcc.Graph(id='pie-fig', figure={})
])

@app.callback(  
     Output('pie-fig', 'figure'),
     Input('date_drdn', 'value'))
def update_graph(selection):
    # if selection:
    dff = df[df['Date'] == selection]
    #print(dff)
    fig = px.pie(dff, values='Transactions', names='Product', color_discrete_sequence=px.colors.sequential.RdBu)
    fig.update_traces(textinfo="label+value+percent").update_layout(title_x=0.5)
    return fig

if __name__ == '__main__':
    app.run_server(debug=True)#, mode='inline'

    enter image description here