Difference between del, remove and pop on lists

Question

>>> a=[1,2,3]
>>> a.remove(2)
>>> a
[1, 3]
>>> a=[1,2,3]
>>> del a[1]
>>> a
[1, 3]
>>> a= [1,2,3]
>         


        

Answer 1

Any operation/function on different data structures is defined for particular actions. Here in your case i.e. removing an element, delete, Pop and remove. (If you consider sets, Add another operation - discard) Other confusing case is while adding. Insert/Append. For Demonstration, Let us Implement deque. deque is a hybrid linear data structure, where you can add elements / remove elements from both ends.(Rear and front Ends)

class Deque(object):

  def __init__(self):

    self.items=[]

  def addFront(self,item):

    return self.items.insert(0,item)
  def addRear(self,item):

    return self.items.append(item)
  def deleteFront(self):

    return self.items.pop(0)
  def deleteRear(self):
    return self.items.pop()
  def returnAll(self):

    return self.items[:]

In here, see the operations:

def deleteFront(self):

    return self.items.pop(0)
def deleteRear(self):
    return self.items.pop()

Operations have to return something. So, pop - With and without an index. If I don't want to return the value: del self.items[0]

Delete by value not Index:

• remove :

  list_ez=[1,2,3,4,5,6,7,8]
  for i in list_ez:
      if i%2==0:
          list_ez.remove(i)
  print list_ez
  

Returns [1,3,5,7]

let us consider the case of sets.

set_ez=set_ez=set(range(10))

set_ez.remove(11)

# Gives Key Value Error. 
##KeyError: 11

set_ez.discard(11)

# Does Not return any errors.