Difference between revisions of "Python"
From Centre for Bioinformatics and Computational Biology
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Revision as of 13:57, 26 June 2019
Contents
Variables
Declaration and typing
#### # Boolean variables can only contain one of two values: True or False # Boolean values are annotated by using the "bool" keyword a: bool = True #### #### # Integers are variables that contain any positive or negative whole number # Integers are annotated using the "int" keyword # Floats are variables that contains any positive or negative decimal # Floats are annotated using the "float" keyword a: int = 15 b: int = -23 c: float = 6.4 d: float = -9.5 #### #### # Strings are variables that contain text # Strings are annotated using the "str" keyword a: str = "This is a string" b: str = 'Strings can be enclosed using single quotes' # Initializing an empty string: a = "" #### #### # Lists are collections of other variables # Lists are annotated using the "list" keyword a: list = ["Some string", 15, 9.6, True] # Initializing an empty list: a = [] #### #### # Sets are lists that cannot contain duplicate values # They also do not keep the order of the variables # Sets are a lot faster than lists when looking for specific values # Sets are annotated using the "set" keyword a: set = {"Some string", 15, 9.6, True} # Initializing an empty set: a = set() #### #### # Tuples are lists that cannot be changed after being created # They are useful when returning multiple values from a function # Tuples are annotated using the "tuple" keyword a: tuple = ("Some string", 15, 9.6, True) # Because tuples cannot be changed there is no point in initializing an empty one #### #### # Dictionaries work of Key - Value pairs # Keys can be any immutable type - integers, floats, strings and tuples # Dictionaries do not keep the their order # Dictionaries are annotated using the "dict" keyword a: dict = {"A": "Some string", "B": 15, "C": 9.6, "D": True} # Initializing an empty dictionary: a = {} ####