Create a set from a series in pandas

Question

I have a dataframe extracted from Kaggle’s San Fransico Salaries: https://www.kaggle.com/kaggle/sf-salaries
and I wish to create a set of the values of a column, for instance ‘Status’.

This is what I have tried but it brings a list of all the records instead of the set (sf is how I name the data frame).

a=set(sf['Status'])
print a

According to this webpage, this should work.
How to construct a set out of list items in python?

Asked By: Julio Arriaga

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Source

Answer 1

If you only need to get list of unique values, you can just use unique method.
If you want to have Python’s set, then do set(some_series)

In [1]: s = pd.Series([1, 2, 3, 1, 1, 4])

In [2]: s.unique()
Out[2]: array([1, 2, 3, 4])

In [3]: set(s)
Out[3]: {1, 2, 3, 4}

However, if you have DataFrame, just select series out of it ( some_data_frame['<col_name>'] ).

Answered By: grechut

Answer 2

With large size series with duplicates the set(some_series) execution-time will evolve exponentially with series size.

Better practice would be to set(some_series.unique()).

A simple exemple showing x16 execution time.

Answered By: Adrien Pacifico

Create a set from a series in pandas

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