setitem and getitem -- python
class, python
Solution
You have several problems:
`extend` is appending essentially a new vector to the end of the original, rather than increasing the length of the original. It's not clear that it needs to return a string representation of the modified vector (unless it's just for debugging purposes).
def extend(self, newlength):
# Assume newlength is greater than the old
self.vector.extend([0] * (newlength - len(self)))
`__setitem__` needs to call `extend` if the key is too large.
def __setitem__(self, key, item):
if key >= len(self):
self.vector.extend(key+1)
self.vector[key] = item
`__getitem__` needs to access the underlying list, not use an undefined attribute
def __getitem__(self, key):
# It's probably better to catch any IndexError to at least provide
# a class-specific exception
return self.vector[key]
Problem
I've created a python program that makes a vector. Now i want to set an item using a function`__setitem__` and`__getitem__`. So for example, if`vector = Vec()`and`vector[3] = 26`would change an empty vector to`[0, 0, 0, 26]`. I need to override the`__getitem__`and`__setitem__` I've listed the code below, but i'm having troubles with the get and set functions. Any advice? ``` class Vec: def __init__(self, length = 0): self.vector = [0]*length def __str__(self): return '[{}]'.format(', '.join(str(i) for i in self.vector)) #This formats the output according to the homework. #Adds '[' and ']' and commas between each 0 def __len__(self): return len(self.vector) def extend(self, newLen): self.vector.append([0]*newLen) return (', '.join(str(j) for j in self.vector)) def __setitem__(self, key, item): self.vector[key] = item def __getitem__(self, key): return self.vector[key] ```