How to add an animated horizontal line in a python animated scatter plotly graph?

Question

Let’s take a sample example of animated scatter graph from plotly site :

import plotly.express as px
df = px.data.gapminder()
fig = px.scatter(df, x="gdpPercap", y="lifeExp", animation_frame="year", animation_group="country",
           size="pop", color="continent", hover_name="country",
           log_x=True, size_max=55, range_x=[100,100000], range_y=[25,90])
fig.show()

I would like to add an animated horizontal line that represents the weighted average life expectancy for each year. I can create a list with those weighted average life expectancy like that :

def weighted_average(df, values, weights):
    # source : https://datagy.io/pandas-weighted-average/
    return sum(df[weights] * df[values]) / df[weights].sum()
L_weighted_average_life_exp = df.groupby('year').apply(weighted_average, 'lifeExp', 'pop').to_list()

We can add an horizontal line using add_hline. I guess that I have to iterate over fig.frames but I don’t know how. I tried something like :

for y,frame in zip(L_weighted_average_life_exp,fig.frames):
   frame.add_hline(y=y, line_width=1, line_dash="dash", line_color="black")

But ‘Frame’ object has no attribute ‘add_hline’.

Would you know please how to do ?

Bonus : add an annotation next to the horizontal line with the amount of the weighted average life expectancy (so the value of y-axis of the horizontal line)

Asked By: Ewdlam

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Source

Answer 1

I found a non-optimal solution, which consists in adding scatters having the form line-ew :

import plotly.express as px
import pandas as pd
import numpy as np

def weighted_average(df, values, weights):
    return sum(df[weights] * df[values]) / df[weights].sum()

df = px.data.gapminder()

df["Point category"] = "Country"

size = df["pop"].mean()

for index, row in pd.DataFrame(df.groupby('year').apply(weighted_average, 'lifeExp', 'pop')).iterrows():
    i = 100
    while i < df["gdpPercap"].max() :
        for ii in [1,5]:#range(1,10):
            df.loc[df.index.max() + 1] = ["Weighted average life exp %s %s"%(i,ii),"Weighted average life exp",index,row[0],size,i*ii,np.nan,np.nan,"Weighted average life exp"]
        i = i*10

fig = px.scatter(df, x="gdpPercap", y="lifeExp", animation_frame="year", animation_group="country",
           size="pop", color="continent", hover_name="country",
           log_x=True, size_max=55,symbol = df["Point category"],range_x=[100,100000], range_y=[25,90],
           symbol_sequence=["circle","line-ew"],color_discrete_sequence=px.colors.qualitative.Dark24)

fig.update_traces(marker=dict(line=dict(width=1,color='Black')))

fig.show()

I’m still open to a better solution

Answered By: Ewdlam

How to add an animated horizontal line in a python animated scatter plotly graph?

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