Python: 'list' object is not callable

Question

have the following code to compare the time of bubblesort and quicksort:

def makeArray(groesseArray, stellenZahlen):
    array = groesseArray * [None]
    for i in range(0,groesseArray):
        array[i] = randint(0,10**stellenZahlen)
    return array

makes array

def bubble(arr):
    n = len(arr)
    for i in range(n - 1):
        for j in range(0, n - i - 1):
            if arr[j] > arr[j + 1]:
                arr[j], arr[j + 1] = arr[j + 1], arr[j]
                #print(arr)

bubblesort algorithm

def quick(arr):
   n = len(arr)
   high = []
   low = []
   if n <= 1:
       return arr
   else:
       pivot = arr.pop()
   for i in arr:
       if i > pivot:
           high.append(i)
       else:
           low.append(i)
   return quick(low) + [pivot] + quick(high)

quicksort algorithm

def timer(func(arr)):
    start = time.time()
    func(arr)
    end = time.time()
    print(end - start)

timer function to measure the time of algorithms

testArray = makeArray(500, 5)

timer(quicksort.quick(testArray))
timer(bubblesort.bubble(testArray))

which is throwing

Traceback (most recent call last):
  File "C:\Users\user\PycharmProjects\Algo\compare.py", line 30, in <module>
    timer(quicksort.quick(testArray))
  File "C:\Users\user\PycharmProjects\Algo\compare.py", line 14, in timer
    func(arr)
TypeError: 'list' object is not callable             

How do I pass a function with a list into the timer function? I tried *args,**kwargs hoping it would be the solutions, but got thrown the same mistake

Thanks in advance

Answer 1

Change your timer function to

def timer(func, arr):
    start = time.time()
    func(arr)
    end = time.time()
    print(end - start)

and call it as follows:

timer(quicksort.quick, testArray)
timer(bubblesort.bubble, testArray)

In your code, you evaluate the sorting function the moment you call timer. The result is a list (returned from the sorting function), which is then passed to timer. Hence the error: you're trying to use that list as a function inside timer.

In the above code, the function and data are passed as two separate arguments. Functions are first-class objects in Python, and can passed to other functions just as any variable can.