The keyword lambda is used in Python to define anonymous functions, that is, functions without a name and described by a single expression. You might just want to perform an operation on a function that can be expressed by a simple expression without naming this function and without defining this function by a lengthy def block.

The name lambda originates from a special branch of calculus and mathematical logic, the -calculus.

We demonstrate the use of lambda-functions by numerically evaluating the following integral:

We use SciPy’s function quad, which requires as its first argument the function to be integrated and the integration bounds as the next two arguments. Here, the function to be integrated is just a simple one-liner and we use the keyword lambda to define it:

import scipy.integrate as si
si.quad(lambda x: x ** 2 + 5, 0, 1)

The syntax is as follows:

lambda parameter_list: expression

The definition of the function lambda...