How to compile all lists in a column into one unique list

Question

I have a pandas dataframe as below:

How can I combine all the lists (in the \'val\' column) into a unique list (set), e.g. [val1, val2, val33, val9, v

Answer 1

You can use str.concat followed by some string manipulations to obtain the desired list.

In [60]: import re
    ...: from collections import OrderedDict

In [62]: s = df['val'].str.cat()

In [63]: L = re.sub('[[]|[]]',' ', s).strip().replace("  ",',').split(',')

In [64]: list(OrderedDict.fromkeys(L))
Out[64]: ['val1', 'val2', 'val33', 'val9', 'val6', 'val7']