Collections / Lists
Mutable
Unlike strings, lists are mutable.
"""Lists are mutable
A list contains multiple values in an ordered sequence
"""
A = [1, 2]; A[1] = 3
assert A == [1, 3]
assert A != [1, 2]
print('Tests passed')
Concat
You can use the + operator concatenate lists.
"""To concatenate two list use + operator
To multiply a list use * operator
"""
A = [1, 2] + [3,4]
B = [9] * 4
C = A * 2
assert A == [1, 2, 3, 4]
assert B == [9, 9, 9, 9]
assert C == [1, 2, 3, 4, 1, 2, 3, 4]
print('Tests passed')
Slice
The slice operator also works on lists.
""" Slice operator [:] works on list, as with strings
The value -1 refers to the last index in a list
"""
a = "abcde"
assert a[:1] == "a"
assert a[1:] == "bcde"
assert a[1:3] == "bc" # limit 3 not included
A = [1, 2, 3, 4, 5]
assert A[:1] != 1
assert A[:1] == [1]
assert A[1:] == [2, 3, 4, 5]
assert A[1:3] == [2, 3] # limit 3 not included
assert A[-1] == 5
assert A[-1:] == [5] # last
print('Tests passed')
Append
You can append the list.
"""List append() extend()
To add an element to a list use append()
To add a list to another list use extend()
The del statement removes values at the index in a list
"""
A = ['a', 'b', 'c']
A.append('x')
assert A != ['a', 'b', 'c']
assert A == ['a', 'b', 'c', 'x']
B = ['d', 'e']
A.extend(B)
assert A != ['a', 'b', 'c']
assert A == ['a', 'b', 'c', 'x', 'd', 'e']
del A[3]
assert A != ['a', 'b', 'c', 'x', 'd', 'e']
assert A == ['a', 'b', 'c', 'd', 'e']
print('Tests passed')
Sorted
Display a sorted list of installed python modules.
"""Display all installed python modules
CLI Examples:
pip list
pip list --outdated
pip show pyperclip
pip install pyperclip
"""
import pkg_resources
pkgs = pkg_resources.working_set
pkgs = sorted(['%s \t %s' % (k.key, k.version) for k in pkgs])
print('\n'.join(pkgs))
# ...
# ufw 0.36
# unattended-upgrades 0.1
# urllib3 1.25.8
Last update: 59 days ago
