labs/Module-2/1.Basic/01-Variable Assignment.ipynb

Variable Assignment

Rules for variable names

• names can not start with a number

• names can not contain spaces, use _ intead

• names can not contain any of these symbols:

  :'",<>/?|\!@#%^&*~-+
  

• it's considered best practice (PEP8) that names are lowercase with underscores

• avoid using Python built-in keywords like list and str

• avoid using the single characters l (lowercase letter el), O (uppercase letter oh) and I (uppercase letter eye) as they can be confused with 1 and 0

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my_dogs = 2

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my_dogs

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my_dogs = ['Sammy', 'Frankie']

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my_dogs

Assigning Variables

Variable assignment follows name = object, where a single equals sign = is an assignment operator

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a = 5

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a

Here we assigned the integer object 5 to the variable name a.
Let's assign a to something else:

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a = 10

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a

You can now use a in place of the number 10:

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a + a

Reassigning Variables

Python lets you reassign variables with a reference to the same object.

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a = a + 10

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a

There's actually a shortcut for this. Python lets you add, subtract, multiply and divide numbers with reassignment using +=, -=, *=, and /=.

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a += 10

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a

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a *= 2

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a

Determining variable type with type()

You can check what type of object is assigned to a variable using Python's built-in type() function. Common data types include:

• int (for integer)
• float
• str (for string)
• list
• tuple
• dict (for dictionary)
• set
• bool (for Boolean True/False)

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type(a)

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a = (1,2)

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type(a)

Simple Exercise

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my_income = 100
tax_rate = 0.1
my_taxes = my_income * tax_rate

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my_taxes