Python Notes and Examples

Data Structures

Lists

Note that slicing gives you a shallow copy.

To loop over items from multiple lists, grouped together:

Invert a Matrix

Dicts

Sets

Note:

non-mutating (and op) mutating
difference (-) difference_update
intersection (&) intersection_update
symmetric_difference (^) symmetric_difference_update
union (|) update

Comprehensions Recap

  • List comprehension: [x**2 for x in range(10)]
  • Dict comprehension: {f'={i}=': i**2 for i in range(10)}
  • Set comprehension: {x for x in 'aabaabbbaababa'}

Data Structures Recap

Type Check for Item Remove Item Add Item
list 'a' in li
li.index('a')
del li[2]
li.pop()
li.remove('a')
li.append('x')
li.extend(['y', 'z'])
li.insert(idx, 'x')
dict 'a' in d del d['a']
d.pop('a')
d.popitem()
d['x'] = 7
d.update()
set 'a' in s s.remove('a')
s.discard('a')
s.pop()
s.add('x')
s.update()