Add hover text in plotly.express

Question

The dataframe df :

        Id      timestamp                C      Date         sig    events1 Start   Peak    Timediff2   datadiff2   B
51253   51494   2020-01-27 06:22:08.330 19.5    2020-01-27   -1.0   0.0     NaN     1.0     NaN          NaN        NaN
51254   51495   2020-01-27 06:22:08.430 19.0    2020-01-27   1.0    1.0     0.0     0.0     NaN          NaN        NaN
51255   51496   2020-01-27 07:19:06.297 19.5    2020-01-27   1.0    0.0     1.0     0.0     3417.967     0.0        0.000000
51256   51497   2020-01-27 07:19:06.397 20.0    2020-01-27   1.0    0.0     0.0     0.0     3417.967     1.0        0.000293
51259   51500   2020-01-27 07:32:19.587 20.5    2020-01-27   1.0    0.0     0.0     0.0     793.290      1.0        0.001261
51260   51501   2020-01-27 07:32:19.687 21.0    2020-01-27

I plotted an interactive graph using:

import pandas as pd
import plotly.express as px

fig = px.line(x=df['Timestamp'], y=df['C'], hover_data=["B"])
fig.add_scatter(x=df['Timestamp'], y=df['C'], mode='markers',  marker_color=df['A'], marker_size=5)

fig.update_layout(plot_bgcolor='#bababa', showlegend=False, width=2400, height=800)

fig.show()

Then to add additional hover data for column C , I added hover_data=["C"] :

fig = px.line(x=df['Timestamp'], y=df['B'], hover_data=["C"])

It returned

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-21-be5860c5172a> in <module>()
     21 import plotly.express as px
     22 
---> 23 fig = px.line(x=df['Timestamp'], y=df['C'], hover_data=["B"])
     24 fig.add_scatter(x=df['Timestamp'], y=df['C'], mode='markers', marker_color=df['A'], marker_size=5)
     25 

3 frames
/usr/local/lib/python3.6/dist-packages/plotly/express/_core.py in build_dataframe(args, attrables, array_attrables)
    931                         "DataFrame or an array is provided in the `data_frame` "
    932                         "argument. No DataFrame was provided, but argument "
--> 933                         "'%s' is of type str or int." % field
    934                     )
    935                 # Check validity of column name

ValueError: String or int arguments are only possible when a DataFrame or an array is provided in the `data_frame` argument. No DataFrame was provided, but argument 'hover_data_0' is of type str or int.

Update:

Tried

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-21-be5860c5172a> in <module>()
     21 import plotly.express as px
     22 
---> 23 fig = px.line(x=df['Timestamp'], y=df['C'], hover_data=df["B"])
     24 fig.add_scatter(x=df['Timestamp'], y=df['C'], mode='markers', marker_color=df['A'], marker_size=5)
     25 

/usr/local/lib/python3.6/dist-packages/plotly/express/_core.py in build_dataframe(args, attrables, array_attrables)
    986                 else:  # numpy array, list...
    987                     col_name = _check_name_not_reserved(field, reserved_names)
--> 988                 if length and len(argument) != length:
    989                     raise ValueError(
    990                         "All arguments should have the same length. "

TypeError: object of type 'float' has no len()

Answer 1

This is how you do it, actually is a little simpler and you can add as much hover data as you want:

    fig = px.line(df,
        x='Timestamp',
        y='C',
        hover_data=[
            'B', 'Z', 
            'A', 'Other'
        ],
   )

Answer 2

You tried:

fig = px.line(x=df['Timestamp'], y=df['C'], hover_data=["B"])

If you read the error message, you'll see that ["B"] should be df['B']

So try:

fig = px.line(x=df['Timestamp'], y=df['C'], hover_data=df["B"])

Edit after comments:

My original answer still stands, but it's no wonder you're still experiencing problems. If you had shared a sample of your dataset, I would most likely have seen the real issue at once.

Anyway, take a look at some of the plotly express docs . There you'll see that px.line does not function the way you seem to expect it to. You're trying to apply dataframe columns such as df['Timestamp'] , df['B'] and df['C'] which leads me to believe that your source data has a so-called wide format. Plotly express functions mostly work with data of a so-called long format. Take a look at https://plotly.com/python/px-arguments/ for more info on this.

If I'm right, then all you'll have to do to make this work for you particular case is transforming your dataframe from a wide to a long format. Update your question with a sample dataframe, and we can take a look at that too.