Python / Plotly Gantt chart: a marker to indicate current date in timeline?

Question

In project management, a Gantt chart lets you see a project's components over a timeline, for example in Plotly. How can one, in a Python context preferably, have a line indicating the current date across this timeline, i.e. today's date, on this graphic? In the Plotly context, there is shapes in which a thin line can be drawn as a shape, but I am having trouble applying it to time-series / Gantt chart, and visually it seems lacking as it doesn't cross out of the graph space (i.e. it does not cross over to the axis) and has no labelling...

Answer 1

Using Plotly 4.9.0, the standard timeline example from the docs (link) can be successfully extended using shapes, as you mentioned:

# plot standard Plotly Gantt example from docs

from pandas import pd
import plotly.express as px
import plotly.offline as py

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")

# add vertical line indicating specific date (e.g. today)

today = '2009-04-20'
fig.update_layout(shapes=[
    dict(
      type='line',
      yref='paper', y0=0, y1=1,
      xref='x', x0=today, x1=today
    )
])
fig.show()