Python dynamically resize list
How to implement dynamic array in PythonA dynamic array automatically grows when you try to make an insertion into a fully occupied list. Once all the space is consumed, and an additional element is ready to be added, the underlying fixed-sized array needs to increase in size.
Implementationimport ctypes
class DynamicArray:
def __init__(self):
self.n=0 # count actual elements
self.size=1 # default array capacity
self.A=self._make_array(self.size) # low level arrays-->creating an array
def __len__(self):
return self.n
def append(self,item):
if self.n==self.size: # not enough memory or rooms
self._resize(2*self.size) # double the capacity
self.A[self.n]=item # I am inserting element into the array
self.n+=1
def _resize(self,new_capacity):
# 1.Creata new Array
B=self._make_array(new_capacity)
self.size=new_capacity
# 2.Copy the elemnts from old array to new array
for i in range(self.n):
B[i]=self.A[i]
#3 .Reassign(delete the previous array)
self.A=B
def _make_array(self,new_capacity):
return (new_capacity*ctypes.py_object)()
def __str__(self):
temp=""
for i in range(self.n):
temp=temp+str(self.A[i])+","
temp=temp[:-1]
return "["+temp+"]"
arr=DynamicArray() # object creation
arr.append(100)
arr.append(200)
arr.append(500)
print(len(arr))
print(arr) Run The highlighted code part gives information about the Dynamic Allocation of a new size, for inserting new elements. |
