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 , )
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