hv.Points(df) with duplicate columns in dataframe

The user guide says dataframes are supported, but I’m having trouble in cases with duplicate columns. The error message is also not very helpful in pinpointing what is going wrong.

Also, API documentation for element.chart.Chart does not mention dataframes, not sure if it should.

import numpy as np
import pandas as pd
import holoviews as hv
data = pd.DataFrame(np.random.randint(-100,100, size=(100, 2)), columns=list("AB"))

# Dataframe with non-duplicate columns works
hv.Points(data[["A", "B"]])

# Dataframe with duplicate columns does not work.
hv.Points(data[["A", "A"]])

# Converting to the numpy array works
hv.Points(data[["A", "A"]].as_matrix())

The last part of the traceback:

print(hv.__version__) # 1.9.4-x-g73c2735e7
print(pd.__version__) # 0.20.3

[philippjfr]

Having read up on the history a bit, I can sort of understand why pandas allows this. When reading in csv files with duplicate columns you don’t want it to fail or mutate your columns automatically. Anyway adding the exception in holoviews should be easy.

[philippjfr]

We could consider putting in a warning if we detect that happening, though?

Good idea, but I think it should be an exception tbh, there is no way we’ll be able to resolve which column is meant if it’s duplicated.