Python Data Structure

Lists

• Mutable
• Ordered sequence
• Notation: []. Ex: Animals = [‘Zebra’, ‘Whale’]
• Accessed by Index. Ex: Animals[0], Animals[-1], Animals[0:1], etc.
• .extend to concate a list. Ex: Animals.extend([‘Horse’,’Chicken]) => Animals = [‘Zebra’, ‘Whale’,’Horse’,’Zebra’]
• .append to add one element to list. Ex: Animals.extend([‘Horse’,’Chicken]) => Animals = [‘Zebra’, ‘Whale’,[‘Horse’,’Zebra’]]
• change one element, Animals[0] = ‘Giraffe’
• delete one element, del(Animals[0])
• clone a list, NewAnimals = Animals[:]

Tuples

• Immutable (can’t modify)
• Ordered sequence
• Notation: (). Ex: Grade = (‘A’,’B’,’C’, 1, 2, 3)
• Accessed by Index. Ex: Grade[0], Grade[-1], Grade[0:2], etc.
• Can be concated. Ex: Grade = Grade + (‘x’, ‘y’, ‘z’)

Dictionaries

• Notation: {}
• Keys: immutable and unique
• Values: can be immutable, mutable, duplicate
• delete dict, del(Dict[‘key’])
• Search key, ‘A’ in Dict, return true or false
• Dict.keys() return list of keys
• Dict.values(0 return list of values

Sets

• Like lists and tuples, but unordered (not record element position)
• unique elements
• Notation: {}
• Lists convert to Sets, set(list)
• Add element with Sets.Add(element)
• Remove element with Sets.Remove(element)
• Search key, ‘search’ in Sets, return true or false
• Math operator: & (perform join), .union, .issubset