Assignments and Variables

Any computer program could be simply described as a sequential list of commands acting on data. When we store data in a memory location with an identifier so we can access it, we have created a variable.

In mathematics, an assignment occurs when you create a variable and assign it a value using an operator. A variable points at a location in memory where the value is stored.

Variable	Operator	Value
a	=	3

In Python, the format is

a = 2

Sometimes the right side of the equation could be a calculation, this will be evaluated before it is assigned. For example, in the line

a = 1 + 2

the variable a will evaluate as 3.

Variable names must start with an underscore or a letter and the Python Style Guide recommends snake_case, which uses underscores to divide words in a variable name. Other possibilities are to use camelCase or MixedCase. Which one you use is less important than using one, consistently throughout a project. Lower case is generally used, but you will see some variations later, for example when you are using global variable names. I use long, descriptive names, for example latitude_in_decimal_degrees.

Do not use any built-in key words as variable names. Look these up now and document them.