Problems with dropdown in a line chart

Dash Python
1

Hi, I’m new to Dash, Plotly and Python and I 'm trying to do a line chart with a multi options dropdown but the options in the dropdown are not filtering the lines in the chart, instead, it have multiple lines on the right side of the line chart which are doing the work the dropdown supposed to do. Could someone have any tips to help me?
Here is the code:

import pandas as pd

import plotly

import plotly.express as px

import dash

import dash_core_components as dcc

import dash_html_components as html

from dash.dependencies import Input, Output

app = dash.Dash(name)

df = pd.read_csv(‘Gráfico2(11.10).csv’, encoding=‘UTF-8’, sep=’;’)

app.layout = html.Div([html.Div([html.H1(children=‘Comparação semanal dos principais destinos brasileiros:’),

                             html.Label(['Escolha as cidades para comparar:'],

                                        style={'font-weight': 'bold'}),

                             dcc.Dropdown(id='cidades',

                                          options=[{'label': x, 'value': x}

                                                   for x in df.sort_values('CIDADE')['CIDADE'].unique()],

                                          value=['Brasil'],

                                          multi=True,

                                          disabled=False,

                                          clearable=False,

                                          searchable=True,

                                          placeholder='Escolha a cidade...',

                                          style={'width': '100%',

                                                 'height': '1000%'}),

                             ]),

                   html.Div([dcc.Graph(id='grafico')]),

                   ])

@ app.callback(

Output('grafico', 'figure'),

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

)

def update_graph(cidades):

dff = df

fig = px.line(data_frame=dff, x="DIA", y="PCTG",

              color='CIDADE')

fig.update_layout(xaxis_title='Semanas',

                  yaxis_title='Mudanças no interesse pelas buscas de voos (%)')

return fig

if name == ‘main’:

app.run_server(debug=True)`Preformatted text`
2

Hi Axbor,
When you pass the value of the dropdown (id=‘cidades’) to the callback:
“def update_graph(cidades):”
Then I do not see that you use the value ‘cidades’ in the x or y values of the graph.
Also I do not understand when do you pass the information of the csv file to the callback to process the data of that table?