Adolfo Correa's questions

What is the use of keyword yieldin Python? What are you doing?

I am trying to understand the following code ¹ :

def _get_child_candidates(self, distance, min_dist, max_dist):
    if self._leftchild and distance - max_dist < self._median:
        yield self._leftchild
    if self._rightchild and distance + max_dist >= self._median:
        yield self._rightchild

The function call (or method in this case) is:

result, candidates = [], [self]
while candidates:
    node = candidates.pop()
    distance = node._get_dist(obj)
    if distance <= max_dist and distance >= min_dist:
        result.extend(node._values)
    candidates.extend(node._get_child_candidates(distance, min_dist, max_dist))
return result

What happens when the _get_child_candidates method is called? Does it return a list or a single element? Is it called again? When will subsequent calls stop?

_{1. The code comes from Jochen Schulz (jrschulz), who created an excellent Python library for metric spaces. This is the link to the full source: Module mspace .}

I build a program that requires to know the files in the working directory ( current working directory ). Therefore, I made the following code, which finds and confirms the existence of the file named arq_buscado:

def encontrar_arq(arq_buscado, camino):
   encontrado = False
   # lista_arq = ls(camino) #función que lista todos los archivos de la ruta
   for nome_arq in lista_arq:
       if nome_arq == arq_buscado:
           encontrado = True
   return encontrado

How can I get the list of all files in a folder in a Python list?

What is the difference between the following lines:

if not x == 'val':

Y

if x != 'val':

Is there a way to check if one is more efficient than the other?

Or, maybe the following block would be better:

if x == 'val':
    pass
else:

They are very close terms and I have already found texts that interchange these concepts, as if in certain situations the definitions are almost the same.

What are the technical definitions that distinguish an API from a library or a Framework ?

Are there situations in which it is permissible to interchange these terms without violating the correct technical definition?