How to store data in a variable from a plotly dropdown?

📊 Plotly Python
1

Hi there,

I’m trying to create a directed graph visualization, which will show the movement of people to different countries during a given year. I am trying to also enable two dropdown filters that will filter the year of the people’s movement and the country they are traveling from (origin_country). Where I am struggling is, I don’t know how to save the user’s dropdown choice into a variable I can use. I had some empty strings I was planning on putting the user’s selection into and then using an if statement when calling the add_trace function to draw the lines (see comments in code). Ideally, I would like the dropdown data to be populated from my travel_paths file (wasn’t sure how to do that either). Any advice on this? Sorry if I’m asking a very basic question, and thanks for any help.

import plotly.graph_objects as go
import pandas as pd

# to further implement
"""
1. be able to filter the data in the future

2. make everything print pretty
"""

countries = pd.read_csv('https://raw.githubusercontent.com/jerguy1928/refugee_map/master/country_centroid_locations.csv')
countries.head()

travel_paths = pd.read_csv('https://raw.githubusercontent.com/jerguy1928/refugee_map/master/test_file.csv')
travel_paths.head()

fig = go.Figure()

#adds country centroids
fig.add_trace(go.Scattergeo(    
	lon = countries['long'],
	lat = countries['lat'],

	hoverinfo = 'text',
    text= countries['country'],
    
	mode = 'markers',
	marker = dict(
		size = 2,
		color = 'rgb(255, 0, 0)',	
	)))

# these 3 variables are currently not used, I was thinking of using them for filtering
year = ""
origin_country = ""
destination_country = ""

button_layer_1_height = 1.08
fig.update_layout(
    updatemenus=[
        go.layout.Updatemenu(
            buttons=list([
				dict(
                    args=["year", "1964"],
                    label="1964",
                    method="update",
                ),
				dict(
                    args=["year", "1972"],
                    label="1972",
                    method="update",
                ),
				dict(
                    args=["year", "1988"],
                    label="1988",
                    method="update",
                ),
				dict(
                    args=["year", "1996"],
                    label="1996",
                    method="restyle",
                ),
            ]),
            direction="down",
            pad={"r": 10, "t": 10},
            showactive=True,
            x=0.1,
            xanchor="left",
            y=button_layer_1_height,
            yanchor="top"
        ),
        go.layout.Updatemenu(
            buttons=list([
                #these are some demo dropdown buttons, i would need to dropdown to be populated from values in the countries csv
				dict(
                    args=["origin_country", "Mozambique"],
                    label="Mozambique",
                    method="update"
                ),
                dict(
                    args=["origin_country", "Rwanda"],
                    label="Rwanda",
                    method="update"
                ),
				dict(
                    args=["origin_country", "Sudan"],
                    label="Sudan",
                    method="update"
                ),
				dict(
                    args=["origin_country", "Cuba"],
                    label="Cuba",
                    method="restyle"
                )
            ]),
            direction="down",
            pad={"r": 10, "t": 10},
            showactive=True,
            x=0.37,
            xanchor="left",
            y=button_layer_1_height,
            yanchor="top"
        ),
    ]
)

for i in range(len(travel_paths)):
	# if (travel_paths['year'][i] == year) and travel_paths['origin'][i] == origin_country: (Was thinking of using this to filter?)
		fig.add_trace(
			go.Scattergeo(
				lon = [travel_paths['start_lon'][i], travel_paths['end_lon'][i]],
				lat = [travel_paths['start_lat'][i], travel_paths['end_lat'][i]],
			
				mode = 'lines+markers', 
				line = dict(width = 1,color = 'red'),
				marker= dict(
					size = 5,
					symbol = 'triangle-down'
				),
				hoverinfo = 'text',
				text= travel_paths['origin'][i] + " -> " + travel_paths['destination'][i]
			)
		)

fig.update_layout(
	title_text = 'Movement of Refugees UNHCR <br> Choose source country from the list <br>',
	showlegend = False,
	geo = go.layout.Geo(
		scope = 'world',
		projection_type = 'mercator',
		showland = True,
        showcountries= True,
		landcolor = 'rgb(243, 243, 243)',
		countrycolor = 'rgb(204, 204, 204)',
	),
)

fig.show()