Get a list from Pandas DataFrame column headers

Question

I want to get a list of the column headers from a Pandas DataFrame. The DataFrame will come from user input, so I won't know how many columns there will be or what they will be called.

For example, if I'm given a DataFrame like this:

>>> my_dataframe     y  gdp  cap 0   1    2    5 1   2    3    9 2   8    7    2 3   3    4    7 4   6    7    7 5   4    8    3 6   8    2    8 7   9    9   10 8   6    6    4 9  10   10    7 

I would get a list like this:

>>> header_list ['y', 'gdp', 'cap'] 

Answer 1

You can get the values as a list by doing:

list(my_dataframe.columns.values) 

Also you can simply use (as shown in Ed Chum's answer):

list(my_dataframe) 

Answer 2

There is a built-in method which is the most performant:

my_dataframe.columns.values.tolist() 

.columns returns an Index, .columns.values returns an array and this has a helper function .tolist to return a list.

If performance is not as important to you, Index objects define a .tolist() method that you can call directly:

my_dataframe.columns.tolist() 

The difference in performance is obvious:

%timeit df.columns.tolist() 16.7 µs ± 317 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)  %timeit df.columns.values.tolist() 1.24 µs ± 12.3 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each) 

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For those who hate typing, you can just call list on df, as so:

list(df)