Adding Annotation Text Yields Integer Error Message

When I adding a vline to my graph it works perfect: fig.add_vline( x=pd.to_datetime('1970-01-01 00:00:00'), line_dash='dot', row=0) [![enter image descript

Solution 1:

• as a workaround, do one call to add_vline() and one call to add_annotation()
• have set parameters to add_annotation() such that annotation will be at top of line

import pandas as pd
import plotly.express as px

ROWS = 20
df = pd.DataFrame({"ColA":pd.date_range("1-jan-1970", freq="4H", periods=ROWS), "ColB":np.random.uniform(1,30, ROWS)})

fig = px.line(df, x="ColA", y="ColB")
fig.update_xaxes(title_font=dict(size=12), tickformat='%X')

fortimein df["ColA"].values:
    time = pd.Timestamp(time).to_pydatetime()
    fig.add_vline(x=time)
    fig.add_annotation(x=time, y=1, yref="paper", text="15")

fig

sub-plots

import pandas as pd
import plotly.express as px

ROWS = 20
df = pd.DataFrame(
    {
        "ColA": pd.date_range("1-jan-1970", freq="4H", periods=ROWS),
        "ColB": np.random.uniform(1, 30, ROWS),
        "Facet": np.repeat(["plot 1", "plot 2"], ROWS // 2),
    }
)

fig = px.line(df, x="ColA", y="ColB", facet_row="Facet")
fig.update_xaxes(title_font=dict(size=12), tickformat="%X")

fortime, y, facet in df[["ColA", "ColB", "Facet"]].values:
    time = pd.Timestamp(time).to_pydatetime()
    fig.add_vline(x=time, row=0if facet == "plot 1"else1)
    fig.add_annotation(x=time, y=y, text="15", row=0if facet == "plot 1"else1, col=0)

fig