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What is the purpose of this append command! - Printable Version

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What is the purpose of this append command! - Captain_farrell - Apr-27-2020 

def square(x):
    return x * x


def my_calculation(x, y):
    result = []
    for i in y:
        result.append(x(i))
    return result


squares = my_calculation(square, [1, 2, 3, 4, 5])

print(squares)


sorry everyone, i am a beginner! in these codes i did not understand why we have to do ? Arrow "result.append(x(i))

or if anyone can explain me all steps, would be much appreciated.
thanks again.

RE: What is the purpose of this append command! - Yoriz - Apr-27-2020 

result.append(x(i))
result is a list
result.append() append an item to the list
x() x is a function passed to my_calculation and the () calls the function
i is the value obtained from iterating through the list y that is passed to my_calculation

RE: What is the purpose of this append command! - Shahmadhur13 - Apr-29-2020 

def square(x):
    return x * x
 
 
def my_calculation(x, y):
    result = []
    for i in y:
        result.append(x(i))
        print(type(x))
    return result
 
 
squares = my_calculation(square, [1, 2, 3, 4])
 
print(squares)
I als come to know that x is function by adding one extra line 9 in above code. But I am wondering there is no pre-defined function called 'x' in there. 'x' is argument in "def square(x)" only. Please enlighten.

RE: What is the purpose of this append command! - buran - Apr-29-2020

(Apr-29-2020, 03:49 AM)Shahmadhur13 Wrote: But I am wondering there is no pre-defined function called 'x' in there. 'x' is argument in "def square(x)" only.
well, there is x parameter in def my_calculation(x, y): too.

By the way, more meaningful names would be better and make easier to follow the code.
e.g. sqare takes a number as argument.
So it would be better to write it like this
def square(number):
    return number * number
same for my_calculation. First param is a function, second is sequence of numbers. e.g.
def my_calculation(func, numbers):


RE: What is the purpose of this append command! - bowlofred - Apr-29-2020

In the function my_calculation, x is the first parameter that is passed in. In your program, this is called at line 13. There, the first parameter is square, which is indeed a function defined earlier in your program.