python DataFrame: get 'set' from DataFrame elements

Question

How can I get 'set' data from DataFrame elements?

For example, if I have a data as

df = DataFrame([['a','b','z'], ['a', 'c'], ['d']])

I would like to get

{'a', 'b', 'c', 'd', 'z'}

(type: set)

If I use for sentence, I can code it. However, if there is another way to calculate with pandas, I would like to use it.

MaxU - stand with Ukraine · Accepted Answer · 2017-08-18 15:40:53Z

In [56]: df.stack().tolist() Out[56]: ['a', 'b', 'z', 'a', 'c', 'd']

or as a set:

In [57]: set(df.stack().tolist()) Out[57]: {'a', 'b', 'c', 'd', 'z'}

Alexander · Accepted Answer · 2017-08-18 15:43:56Z

s = set(df.values.ravel()) >>> s {None, 'a', 'b', 'c', 'd', 'z'}

Technically, the value None should be in the result. You could always remove it with s.remove(None) if required.

Miriam Farber · Accepted Answer · 2017-08-18 18:28:47Z

Try this:

A=[] [A.extend(item)for item in df.values.tolist() ] A = list(set([i for i in A if i is not None])) A Out[1224]: ['a', 'b', 'c', 'd', 'z']

3 Answers 3