Python Pandas Convert columns to list from dataframe

Question

I've been getting lists in emails with line breaks for each item what I want to do is just copy and paste then save as csv and have a script create a python list out of the data. Since it's columns from the paste to the file I'm getting improper formatting, if I change I do a replace on the line breaks for commas it look a bit better but still since it's converted from a column it's not correct and with mylist.values.tolist() it still doesn't work. Here's what I have and what's happening. I can do this with the builtin csv library but was wondering how to do it in p

Email format that I'm pasting:

Fox Chicken Cat Dog

When I put into csv and put the commas:

Fox, Chicken, Cat, Dog

What I get back for output:

mylist.values.tolist()

[['Fox, nan'], ['Chicken, nan'], ['Cat, nan'], ['Dog, nan']]

I just want:

['Fox','Chicken', 'Cat', 'Dog']

Further, if I try to assign my_list = mylist.values.tolist() I get an exception the unsupported operands 'str' and 'type'.

Any help would be appreciated since I like pandas more than builtin, if it's not possible elegantly I'll have to go back.

Are you sure your output is exactly as you typed it? Is it not [['Fox', nan], ['Chicken', nan], ['Cat', nan], ['Dog', nan]]? — DYZ
– DYZ, Commented Dec 2, 2016 at 2:54
what type is mylist? the exception in the assignment is strange, how could I duplicate it? please, put a small minimal but complete example of the exception. — eguaio
– eguaio, Commented Dec 2, 2016 at 2:55
You are correct, it's a couple hundred mac addresses so I didn't copy and paste, sorry. — Fallacy11
– Fallacy11, Commented Dec 2, 2016 at 2:56
@eguaio >>> type(mylist) <class 'pandas.core.frame.DataFrame'> I can add code but it's really just a list copied into excel columns and read with pandas. — Fallacy11
– Fallacy11, Commented Dec 2, 2016 at 3:01

DYZ · Accepted Answer · 2016-12-02 02:57:06Z

1

If your output is [['Fox', nan], ['Chicken', nan], ['Cat', nan], ['Dog', nan]] (which I believe it is), then you can unzip the list into two parts:

names,nans=zip(*mylist.values.tolist()) 
# both names and nuns are tuples
names = list(names)

answered Dec 2, 2016 at 2:57

DYZ

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1 Comment

eguaio Over a year ago

I would agree it is a little strange, but the tolist() method really returns a list of strings encoding all the values separated by comma, as stated in the question. This will not work.

eguaio · Accepted Answer · 2016-12-02 02:58:56Z

0

try:

slist = mylist.values.tolist()
ilist = [l[0].split(',')[0].strip() for l in slist]

answered Dec 2, 2016 at 2:58

eguaio

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Comments

Ken Wei · Accepted Answer · 2016-12-02 19:42:27Z

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The formatting from the copy-pasting is somehow causing pandas to think you've given it a (4 x 2) table. So in this particular case, if your dataframe is mylist, you'll want mylist.iloc[:,0].values.tolist().

But really, just reading the file into a string and calling .split() is much simpler, faster and more robust.

answered Dec 2, 2016 at 19:42

Ken Wei

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