Altair : Duplicate signal name: "selector080_columnName"

Using Streamlit
1

I am trying to create a regression line using Altair and Streamlit and I am getting the following error while trying to execute the same:
Duplicate signal name: “selector080_Fiscal_Week”

Below is the code I am using:
import streamlit as st
import pandas as pd
import numpy as np
import altair as alt

def scatter_chart(f, col1, col2):
scatter = alt.Chart(f).mark_point().encode(
x=col1,
y=col2,
tooltip=[col1, col2]).interactive()
reg = scatter.transform_regression(col1,col2).mark_line()
return scatter + reg

st.altair_chart(scatter_chart(df, scatter_opt1, scatter_opt2), use_container_width = True)

Please let me know the issue and how to resolve it ?

2

Hi @anshul and welcome to the forums !

The interactive() part should be on the concatenated chart :

import streamlit as st
import pandas as pd
import numpy as np
import altair as alt
from vega_datasets import data

df = data.iris()

def scatter_chart(f, col1, col2):
	scatter = alt.Chart(f).mark_point().encode(
		x=col1,
		y=col2,
		tooltip=[col1, col2]
	)
	reg = scatter.transform_regression(col1,col2).mark_line()
	return (scatter + reg).interactive() # <--- here

st.write(df)
st.altair_chart(scatter_chart(df, 'sepalLength', 'sepalWidth'), use_container_width = True)

it can also be on the reg definition but it’s clearer to make all of the chart interactive by putting it on the upmost definition :wink:

3

Thanks a lot andfanilo. It works. :slight_smile: