Convert pandas df columns to paired list [duplicate]

Question

If I have a df like this:

df1 = pd.DataFrame({'col1': [1, 1, 2, 2], 'col2': [10, 20, 10, 20]})

How would I get a list that pairs each row of col1 and col2 like so:

outputlist = [[1, 10], [1, 20], [2, 10], [2, 20]]

I've found ways to turn lists into df columns, but not the other way around!

Dani Mesejo · Accepted Answer · 2019-01-03 19:51:02Z

2

You could do (see tolist):

import pandas as pd df1 = pd.DataFrame({'col1': [1, 1, 2, 2], 'col2': [10, 20, 10, 20]}) result = df1.values.tolist() print(result)

Output

[[1, 10], [1, 20], [2, 10], [2, 20]]

answered Jan 3, 2019 at 19:51

Dani Mesejo

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5 Comments

kabanus Over a year ago

Not even sure tolist is needed.

Dani Mesejo Over a year ago

@kabanus What do you mean?

kabanus Over a year ago

From OP's requirements the value array might be good enough (maybe better?) Anyway, nice answer.

Liquidity Over a year ago

How would I select specific columns? eg if I have a col3, but I only want col1 and col2 to be in the output? I realize I could just drop col3 and then use .tolist(), but I was just curious.

Dani Mesejo Over a year ago

I guess you could do: df1[['col1', 'col2']].values.tolist()

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