Python namedtuple : How can I reuse variables used to create attributes in a namedtuple to get values from the namedtuple?

Question

How can I use colname_1 to get a value for an attribute foo of a namedtuple?

from collections import namedtuple

colname_1 = 'foo'
colname_2 = 'bar'

Farm = namedtuple('Farm', 'foo bar')
farm = Farm('apple', 'banana')

farm.foo  # OK
farm.colname_1  #  of course this doesn't work!

Answer 1

Use getattr():

getattr(farm, colname_1) # 'apple'

From the named tuple docs:

To retrieve a field whose name is stored in a string, use the getattr() function

Alternately, although clunky, you can index into the ._fields attribute:

farm[[i for i, f in enumerate(farm._fields) if f == colname_1][0]] # 'apple'