R ggplotly to Python plotly conversion issues (with beginnings of a possible fix)

Hello Plotly team! I want to make graphs in R’s ggplotly and then run existing Plotly Python code to reformat them. However, I’m getting errors when importing a ggplotly JSON created in R into Plotly in Python.

To fix these errors, I have to resort to either running code to fix them in the JSON (2a below) or setting pio.read_json()’s skip_invalid parameter to true (2b below). , I believe the JSON is valid because 1) The JSON renders correctly in Plotly.js 2) The JSON comes from simple graphs made in ggplotly.

R code:

library(ggplot2)
library(plotly)

# Data
a = data.frame(x = (0:4), y = c(2, 4, 1, 6, 8), group="A")
b = data.frame(x = (0:4), y = c(3, 2, 5, 4, 7), group="B")
data <- rbind(a, b)

# Graph 
fig <- ggplot(data, aes(x, y, color = group)) + geom_line()

#Convert to ggplotly, save as JSON, and export
fig_ggplotly <- ggplotly(fig)
fig_ggplotly_json<-plotly_json(fig_ggplotly, FALSE)
write(fig_ggplotly_json,'fig_ggplotly.json')

2a: Python code - Errors when using json.load( )

import json
import sys

with open(“fig_ggplotly.json", "r") as f:
    fig_ggplotly_json = json.load(f)
print(fig_ggplotly_json)

go.Figure(fig_ggplotly_json) # throws errors; solved with ggplotly_to_plotly.py 

 # Example of invalid parameter:  
fig_ggplotly_json['layout']['font']['family'] # shows value as ‘’. Does not throw error.

2b: Python code - Using pio.read_json() with skip_invalid=True

import json
import sys
import plotly.io as pio

with open("fig_ggplotly.json", "r") as f:
    fig_ggplotly_pio = pio.read_json(f, skip_invalid=True)

# Example of invalid parameter that gets completely eliminated using skip_invalid, causing later issues:   
fig_ggplotly_pio.to_dict()['layout']['font']['family'] #throws KeyError

Skipping elements of the JSON seems to be inviting a loss of fidelity. Indeed, the reformatting code I apply has issues handling some elements due to the skipped invalid parameters. I’ve identified a number of specific elements that are not compatible with Plotly.py and would appreciate it if Plotly.py were to handle this valid input correctly. The ggplotly_to_plotly conversion code, which highlights many of the problem areas for basic graphs, can be found here.

Start by reproducing the supplied R ggplotly export and importing it with Python's pio.read_json() and go.Figure(). Read the linked ggplotly_to_plotly.py gist for the identified incompatibilities. Done means compatible ggplotly JSON imports without skip_invalid=True while preserving fields such as layout.font.family.