LANGUAGE » PYTHON
List
Constructors
python
my_list = ['a', 'b', 'c']
my_list = list(obj)
my_list = [expression for value in input_set (if predicate)]Operators
python
value = my_list[1] # Get element from index
my_list = list1 + list2 # Concatenation
my_list = my_list[start:stop:step] # Slicing (step default is 1)Methods
| Method | Description |
|---|---|
insert(index, object) | Insert an item at a given position. |
append(object) | Add an item to the end of the list. |
extend(iterable) | Extend the list by appending all the items from the iterable. |
remove(object) | Removes the first item from the list which matches the specified value. |
pop() | Removes and returns the item at the specified index (default to last item). |
index(item) | Returns the index of the first occurrence of the specified list item. |
count(item) | Returns the number of times the specified item appears in the list. |
sort() | Sorts the list in place. |
reverse() | Reverse the elements of the list in place. |
Functions
These are builtin keywords, the list must be passed as a parameter.
| Function | Description |
|---|---|
len(collection) | Returns an int type specifying number of elements in the collection. |
min(collection) | Returns the smallest item from a collection. |
max(collection) | Returns the largest item in an iterable or the largest of two or more arguments. |
sum(iterable) | Returns a total of the items contained in the iterable object. |
sorted(iterable) | Returns a sorted list from the iterable. |
reversed(sequence) | Returns a reverse iterator over a sequence. |
all(iterable) | Returns a Boolean value that indicates whether the collection contains only values that evaluate to True. |
any(iterable) | Returns a Boolean value that indicates whether the collection contains any values that evaluate to True. |
enumerate(sequence) | Returns an enumerate object. |
zip(iterable, ...) | Returns a list of tuples, where the i-th tuple contains the i-th element from each of the argument sequences or iterables. |
map(func, iterable) | Return an iterator that applies function to every item of iterable, yielding the results. |
reduce(func, iterable, start) | Applies function of two arguments cumulatively to the items of iterable, so as to reduce the iterable to a single value. Requires: from functools import reduce |
Examples
List generation
python
my_list = list(range(3)) # => [0, 1, 2]
my_list = list(range(1, 7)) # => [1, 2, 3, 4, 5, 6]
my_list = list(range(1, 7, 2)) # => [1, 3, 5]List comprehension
python
my_list = [x for x in range(1, 6)] # => [1, 2, 3, 4, 5]
my_list = [x * 2 for x in range(1, 6)] # => [2, 4, 6, 8, 10]
my_list = [x for x in range(1, 6) if x % 2 == 0] # => [2, 4]List operations
Map:
python
map(lambda x: x*x, my_list)Reduce:
python
from functools import reduce
reduce(lambda total, cur: total + cur, numbers, 0)Slicing
python
my_list = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
sliced1 = my_list[1:8:2] # => [1, 3, 5, 7]
sliced2 = my_list[::2] # => [0, 2, 4, 6, 8]
sliced3 = my_list[1:8] # => [1, 2, 3, 4, 5, 6, 7]
sliced4 = my_list[::-1] # => [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]Copy
Shallow copy:
python
list_copy = my_list.copy()Deep copy:
python
from copy import deepcopy
list_copy = deepcopy(my_list)Sort
python
list_of_dicts.sort(key=itemgetter('date'))
my_list = sorted(list_of_instances, key=attrgetter('type'))