What is the use of the "starmap" function in Python?

In Python, the starmap() function is part of the itertools module and is used to apply a specified function to a sequence of argument tuples. It returns an iterator that yields the results of applying the function to each argument tuple.

The starmap() function takes two arguments:

  • func: The function to apply to each argument tuple. It should take multiple arguments and return a single value.
  • iterable: The input iterable of argument tuples.

Here's an example to demonstrate the usage of the starmap() function:

import itertools

def add(a, b):
    return a + b

arg_tuples = [(1, 2), (3, 4), (5, 6)]
result_iterator = itertools.starmap(add, arg_tuples)

for result in result_iterator:

# Output:
# 3
# 7
# 11

In this example, the starmap() function applies the add() function to each tuple in arg_tuples. The add() function takes two arguments and returns their sum. The resulting iterator, result_iterator, yields the results of the addition operation for each argument tuple.

The starmap() function is useful when you have a sequence of argument tuples and want to apply a function to each tuple. It simplifies the process of unpacking the tuples and passing the individual elements as arguments to the function. It is particularly handy when working with iterable data structures that store multiple values per element (e.g., tuples, lists) and you want to apply a function to each combination of values.

It's important to note that the starmap() function assumes that each argument tuple has the correct number of elements that match the function's parameter list. If there is a mismatch, such as a tuple with fewer or more elements than expected by the function, an error will occur.

Also, keep in mind that the starmap() function is lazy and produces results on-the-fly as you iterate over the resulting iterator. This can be beneficial for performance and memory efficiency, especially when working with large or infinite iterables.

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