How to compose a function n times in python

how to apply a function n times in python
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calling a function n times
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python repeat function
python reduce

I know how to compose two functions by taking two functions as input and output its composition function but how can I return a composition function f(f(...f(x)))? Thanks

def compose2(f, g):
    return lambda x: f(g(x))

def f1(x):
    return x * 2
def f2(x):
    return x + 1

f1_and_f2 = compose2(f1, f2)
f1_and_f2(1)

You use a loop, inside a nested function:

def compose(f, n):
    def fn(x):
        for _ in range(n):
            x = f(x)
        return x
    return fn

fn will be have closure that retains references to the f and n that you called compose with.

How to compose a function n times in python, You use a loop, inside a nested function: def compose(f, n): def fn(x): for _ in range(n): x = f(x) return x return fn. fn will be have closure that� A function is a block of organized, reusable code that is used to perform a single, related action. Functions provide better modularity for your application and a high degree of code reusing. As you already know, Python gives you many built-in functions like print(), etc. but you can also create your own functions.

Note this is mostly just copied from https://stackoverflow.com/a/16739439/2750819 but I wanted to make it clear how you can apply it for any one function n times.

def compose (*functions): 
    def inner(arg): 
        for f in reversed(functions): 
            arg = f(arg) 
        return arg 
    return inner

n = 10
def square (x): 
    return x ** 2

square_n = [square] * n
composed = compose(*square_n)
composed(2)

Output

179769313486231590772930519078902473361797697894230657273430081157732675805500963132708477322407536021120113879871393357658789768814416622492847430639474124377767893424865485276302219601246094119453082952085005768838150682342462881473913110540827237163350510684586298239947245938479716304835356329624224137216

Repeat, Write a procedure which accepts as arguments another procedure and a positive integer. 45 Phix; 46 Phixmonti; 47 PicoLisp; 48 PowerShell; 49 Prolog; 50 Python Given the function we want to execute multiple times is of The two classes in this recipe show two styles of function composition. The only difference is when the second function, g, returns a tuple.compose passes the results of g as f’s first argument anyway, while mcompose treats them as a tuple of arguments to pass along.

if you want to make it one line composition,

then try this,

def f1(x):
    return x * 2
def f2(x):
    return x + 1

>>> out = lambda x, f=f1, f2=f2: f1(f2(x)) # a directly passing your input(1) with 2 function as an input (f1, f2) with default so you dont need to pass it as an arguments
>>> out(1)
4
>>> 

>>> def compose(f1, n):
...   def func(x):
...     while n:
...       x = f1(x)
...       n = n-1
...     return x
...   return func

>>> d = compose(f1, 2)
>>> d(2)
8
>>> d(1)
4
>>> 

Loops - Mathematical Python, A for loop allows us to execute a block of code multiple times with some For example, here are two ways to write a function which computes the sum of� While I don’t consider myself a functional programming expert, all those hours spent in Haskell, Lisp and Scheme definitively changed my way of programming. So, after seeing a lot of unnecessarily complex implementations of function composition in Python on the Web, I decided to write this article to present a simple yet powerful solution that covers all use cases. If you are familiar with

you can use functools.reduce:

from functools import reduce

def compose(f1, f2):
    return f2(f1) 

reduce(compose, [1, f2, f1]) # f1(f2(1))

output:

4

if you want to compose same function n times:

n = 4
reduce(compose, [1, *[f1]*n]) # f1(f1(f1(f1(1))))

output:

16

Calling function multiple times : learnpython, Calling function multiple times. I know for loops This takes advantage of Python's ability to read and write to text files, which can be used as mini- databases. Function composition is the way of combining two or more functions in such a way that the output of one function becomes the input of the second function and so on. For example, let there be two functions “F” and “G” and their composition can be represented as F(G(x)) where “x” is the argument and output of G(x) function will become

Python for loop - learn Python for loop statement, The following example uses Python for statement to go through a With the help of the range() function, we can repeat a code block n times. Python also accepts function recursion, which means a defined function can call itself. Recursion is a common mathematical and programming concept. It means that a function calls itself. This has the benefit of meaning that you can loop through data to reach a result.

Python, The internal function of itertools library, repeat() can be used to achieve the solution to the above problem. filter_none. edit close. play_arrow. link brightness_4 Method #2 : Using itertools.chain.from_iterable() + itertools.repeat() This particular problem can also be solved using python inbuilt functions of itertools library. The repeat function, as name suggests does the task of repetition and grouping into a list is done by the from_iterable function.

Loops in Python, A loop allows us to execute some set of statement multiple times. this is to create a Python script and call print() function 100 times as follows: We could instead use while loop to re-write the above program as follows:� hello world hello world hello world hello world hello world. To print out "hello world" 10 times, the code would be as that shown below. for i in range (10): print ("hello world") The statement, "hello world", now gets printed out 10 times.

Comments
  • This code above works perfectly, is this not what you want your code to do?
  • its working .. what do you want? what is your expected result?
  • Does this answer your question? Composing functions in python
  • I mean I would like to know how to write a function that takes f1 and n as input and outputs f1(f1(...f1(x)) function? Thanks.
  • So, what is n ?
  • I would just like to say that this uses recursion, which can be difficult to grasp for less experienced programmers. This link may be helpful if you don't yet understand the concept (although its use in this answer is quite simple): Thinking Recursivley
  • Thanks, may I know how to write a function that takes f1 and n as input and outputs f1(f1(...f1(x)) function? where f1 is composed n times.