Gantt chart docs - TypeError: Object of type timedelta is not JSON serializable

[helen-fornazier]

Hi,

I am following this docs to generate a gantt chart https://github.com/plotly/plotly.py/blob/doc-prod/doc/python/gantt.md

But this is what I get:

Traceback (most recent call last):
  File "/home/ccu/ccu/mesa-performance-tracking/mesa-ci-status/gantt-chart-test.py", line 12, in <module>
    fig.show()
  File "/home/ccu/.local/lib/python3.10/site-packages/plotly/basedatatypes.py", line 3390, in show
    return pio.show(self, *args, **kwargs)
  File "/home/ccu/.local/lib/python3.10/site-packages/plotly/io/_renderers.py", line 403, in show
    renderers._perform_external_rendering(fig_dict, renderers_string=renderer, **kwargs)
  File "/home/ccu/.local/lib/python3.10/site-packages/plotly/io/_renderers.py", line 340, in _perform_external_rendering
    renderer.render(fig_dict)
  File "/home/ccu/.local/lib/python3.10/site-packages/plotly/io/_base_renderers.py", line 748, in render
    html = to_html(
  File "/home/ccu/.local/lib/python3.10/site-packages/plotly/io/_html.py", line 144, in to_html
    jdata = to_json_plotly(fig_dict.get("data", []))
  File "/home/ccu/.local/lib/python3.10/site-packages/plotly/io/_json.py", line 123, in to_json_plotly
    return json.dumps(plotly_object, cls=PlotlyJSONEncoder, **opts)
  File "/usr/lib/python3.10/json/__init__.py", line 238, in dumps
    **kw).encode(obj)
  File "/home/ccu/.local/lib/python3.10/site-packages/_plotly_utils/utils.py", line 59, in encode
    encoded_o = super(PlotlyJSONEncoder, self).encode(o)
  File "/usr/lib/python3.10/json/encoder.py", line 199, in encode
    chunks = self.iterencode(o, _one_shot=True)
  File "/usr/lib/python3.10/json/encoder.py", line 257, in iterencode
    return _iterencode(o, 0)
  File "/home/ccu/.local/lib/python3.10/site-packages/_plotly_utils/utils.py", line 136, in default
    return _json.JSONEncoder.default(self, obj)
  File "/usr/lib/python3.10/json/encoder.py", line 179, in default
    raise TypeError(f'Object of type {o.__class__.__name__} '
TypeError: Object of type timedelta is not JSON serializable

I installed with pip, and the version is the same indicated on top here https://plotly.com/python/gantt/

ccu@ginger ~/c/mesa (cuttlefish)> pip show plotly
Name: plotly
Version: 5.14.0
Summary: An open-source, interactive data visualization library for Python
Home-page: https://plotly.com/python/
Author: Chris P
Author-email: chris@plot.ly
License: MIT
Location: /home/ccu/.local/lib/python3.10/site-packages
Requires: packaging, tenacity
Required-by: 

So I'm wondering if this is a bug or if I'm doing something wrong, or maybe the docs is outdated (and I can help with that once I figure the right way to implement it).

Thanks.

[AaronStiff]

@helen-fornazier which example in the docs specifically generated the error? I was able to run the first few examples successfully with the same version as you.

[helen-fornazier]

the first example:

import plotly.express as px
import pandas as pd


df = pd.DataFrame([
    dict(Task="Job A", Start='2009-01-01', Finish='2009-02-28'),
    dict(Task="Job B", Start='2009-03-05', Finish='2009-04-15'),
    dict(Task="Job C", Start='2009-02-20', Finish='2009-05-30')
])

fig = px.timeline(df, x_start="Start", x_end="Finish", y="Task")
fig.update_yaxes(autorange="reversed") # otherwise tasks are listed from the bottom up
fig.show()

and just for information:

$python --version
Python 3.10.6

[helen-fornazier]

All the first examples before Deprecated Figure Factory gives me this error.

The Deprecated Figure Factory, Group Tasks Together and Color by Numeric Variable works, but not the ones under Gantt Charts and Timelines with plotly.express section

[aberres]

@helen-fornazier Are you using Pandas 2? Then the fix might be here: #4103

[arg0d]

I'm experiencing the same issue.

$ pip freeze | grep pandas
pandas==2.0.0

Which version of pandas should we use?

[aberres]

@arg0d A downgrade to 1.5.3 should help.

pip install pandas==1.5.3

[helen-fornazier]

Yes, I was using pandas==2.0.0, downgrading with pip install pandas==1.5.3 works. Thanks.

[kaibir]

Since #4103 has been merged about an hour ago (and closed #4102), this one here can be closed too, can't it? @helen-fornazier

[alexcjohnson]

@helen-fornazier would you try again with the new v5.14.1 and pandas v2.0.0 and let us know if the issue is resolved? Thanks!

[helen-fornazier]

@helen-fornazier would you try again with the new v5.14.1 and pandas v2.0.0 and let us know if the issue is resolved? Thanks!

It works! Looks solved. Thanks! Closing the issue.