Set & List Comprehension’s in Python

Set & List Comprehension’s in Python

Sets

• A set is an unordered collection
• Eliminates duplicate entries.
• Empty set my_set= set()
• my_set = {1,2,3,4}

:-

• add my_set.add(5)
• remove /delete

my_set.remove(3)    # Raises KeyError if element notfound
my_set.discard(3)   # Does nothing if element not found
my_set.clear()      # Removes all elements

• Length len(my_set)

set operations

• union seta.union(setb) or seta | setb
• Intersection seta.intersection(setb) or seta & setb
• Difference seta.difference(setb) or seta - setb
• Symmeteric difference (unique elements of both sets) seta.symmetric_difference(setb) or set ^ setb

Advanced List

• creating list in single line [expression for item in iterable if condition]

eg : sqaures = [x*x for x in range(0,9) if x%2 == 0]

• Slicing list list[start:end:step]
• Reverse/sort sort(), reverse()
• Nested List {list in list : multidimensional list }

[[1,2],[3,4]]

• List Copy

list.copy() list.deepcopy()

• map / filter
• lambda expression map( lambda function, list/range) filter(lamda condition , )