__import__() function in Python

__import__() is a built-in function in Python that is used to dynamically import modules. It allows us to import a module using a string name instead of the regular "import" statement. It's useful in cases where the name of the needed module is know to us in the runtime only, then to import those modules in runtime, we use __import__() function.

Let's understand with an example.

s = "math"
m = __import__(s)

print(m.sqrt(16))  # Output: 4.0

4.0

Explanation:

• Here, we assign the name of the required module in 's', then __import__(s) imports the module and assign it to 'm'.
• Now all the methods of the math module can be accessed using the object 'm'.

Syntax

__import__(name, globals, locals, fromlist, level)

Parameters:

• name: Name of the module to be imported
• globals (optional): The global variables (usually globals())
• locals (optional): The local variables (usually locals())
• formlist (optional): Objects or submodules to be imported (as a list)
• level (optional): Specifies whether to use absolute or relative imports. The default is -1.

Return Type: returns a reference to the imported module object.

Examples of __import__():

Example 1:

In this example, we will use the __import__() function to import the Python NumPy module dynamically to create an array.

np = __import__('numpy')

# array from numpy
a = np.array([1, 2, 3])

print(type(a))

<class 'numpy.ndarray'>

Explanation:

• __import__('numpy') imports the numpy module and it's methods can be accessed using "np".
• notice that parameters like globals, locals, etc are not provided here so the function will assume the default values for them.

Example 2:

Now, instead of trying to import the whole module, let's import only some specific functions from a module suing fromlist parameter.

m = __import__('math', globals(), locals(), fromlist=['factorial'])

print(m.factorial(5))

Explanation:

• we are importing 'math' module here.
• globals() and locals() ensure the module integrates correctly with the current scope.
• fromlist=['factorial'] ensures that only factorial is imported.