python - Calling a function twice with different argument changes the values of function output that is already called

Question

I got this weird problem that I cannot even make a title with concision.

Here, I first describe the problem, and show an arbitrary code that is a simplified version of my original code that generates the same problem.

I have a function(say 'A') of another function(say 'B'). 'A' returns output of 'B'. And B has two different modes with respect to its parameter.

Now, If I call 'A' twice with identical parameter to 'B', it shows same results twice.

But If I insert 'B' Twice in 'A' with different parameter, but output only the first 'B', 'A' shows the output of 'second B'.

Here is the code. (I repeat that this is just an arbitrary code that I created to show the problem with ease.)

arr=[]
for i in range(5):
  arr.append(i)

def B(arr, rand=False):
  cnt=[]
  if rand:    
    ind=np.random.choice(arr, len(arr))    
    for i, val in enumerate(arr):
      if val in arr:
        arr[arr.index(val)]+=1

  for i in arr:
    if i>2:
      cnt.append(i)
  return cnt

def A(arr):
  firstB=B(arr)
  secondB=B(arr, rand=True)
  return np.std(firstB)

for i in range(5):
  print(A(arr))

if you remove secondB, output will be

0.5
0.5
0.5
0.5
0.5

But if you retain secondB, eventhough the output is still firstB, the outputs vary. like this.

0.5
0.816496580927726
1.118033988749895
1.4142135623730951
1.4142135623730951

How is this like this?

question from:https://stackoverflow.com/questions/65951265/calling-a-function-twice-with-different-argument-changes-the-values-of-function

Answer 1

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