I have a list of integers and I was wondering if it would be possible to add to individual integers in this list.
Python provides an inbuilt function sum() which sums up the numbers in the list. Syntax: sum(iterable, start) iterable : iterable can be anything list , tuples or dictionaries , but most importantly it should be numbers.
There are two methods to add elements to the list. add(E e): appends the element at the end of the list. Since List supports Generics, the type of elements that can be added is determined when the list is created. add(int index, E element): inserts the element at the given index.
One of the most common ways to add an integer to a list, let alone any other type of data, is to use the append() method. This will simply add a single integer to the very end of the list. There are a number of other ways to add one or more integers to a list, which we'll explore in the next sections.
Here is an example where the things to add come from a dictionary
>>> L = [0, 0, 0, 0]
>>> things_to_add = ({'idx':1, 'amount': 1}, {'idx': 2, 'amount': 1})
>>> for item in things_to_add:
... L[item['idx']] += item['amount']
...
>>> L
[0, 1, 1, 0]
Here is an example adding elements from another list
>>> L = [0, 0, 0, 0]
>>> things_to_add = [0, 1, 1, 0]
>>> for idx, amount in enumerate(things_to_add):
... L[idx] += amount
...
>>> L
[0, 1, 1, 0]
You could also achieve the above with a list comprehension and zip
L[:] = [sum(i) for i in zip(L, things_to_add)]
Here is an example adding from a list of tuples
>>> things_to_add = [(1, 1), (2, 1)]
>>> for idx, amount in things_to_add:
... L[idx] += amount
...
>>> L
[0, 1, 1, 0]
You can append to the end of a list:
foo = [1, 2, 3, 4, 5]
foo.append(4)
foo.append([8,7])
print(foo) # [1, 2, 3, 4, 5, 4, [8, 7]]
You can edit items in the list like this:
foo = [1, 2, 3, 4, 5]
foo[3] = foo[3] + 4
print(foo) # [1, 2, 3, 8, 5]
Insert integers into the middle of a list:
x = [2, 5, 10]
x.insert(2, 77)
print(x) # [2, 5, 77, 10]
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