What does this mean: key=lambda x: x[1] ?

Question

I see it used in sorting, but what do the individual components of this line of code actually mean?

key=lambda x: x[1]

What\'s lambda

Answer 1

One more example of usage sorted() function with key=lambda. Let's consider you have a list of tuples. In each tuple you have a brand, model and weight of the car and you want to sort this list of tuples by brand, model or weight. You can do it with lambda.

cars = [('citroen', 'xsara', 1100), ('lincoln', 'navigator', 2000), ('bmw', 'x5', 1700)]

print(sorted(cars, key=lambda car: car[0]))
print(sorted(cars, key=lambda car: car[1]))
print(sorted(cars, key=lambda car: car[2]))

Results:

[('bmw', 'x5', 1700), ('citroen', 'xsara', 1100), ('lincoln', 'navigator', 2000)]
[('lincoln', 'navigator', 2000), ('bmw', 'x5', 1700), ('citroen', 'xsara', 1100)]
[('citroen', 'xsara', 1100), ('bmw', 'x5', 1700), ('lincoln', 'navigator', 2000)]