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Introduction to Python
course content

Course Content

Introduction to Python

Introduction to Python

1. First Acquaintance
The Very First StepsCommentsSome Simple MathMore Challenging MathChallengeBringing It All Together
2. Variables and Types
Storing NumbersNaming RulesUsing VariablesData TypesNumbersChallengeStoring TextString IndexingNegative Indexing and LengthString SlicingChallengeConcatenation
3. Conditional Statements
Boolean Data TypeChallenge: Comparison OperatorsCombining ConditionsChallenge: Logical OperatorsMembership Operators and Types ComparisonSimple if/else ExpressionsChallenge: Grocery StoreChallenge: Odd and Evenif/elif/else ExpressionsChallenge: Grocery Store ExtendedChallenge: Positive, Negative or Zero
4. Other Data Types
What Is a List?List MethodsChallengeNested ListsChallengeWhat Is a Tuple?Tuple MethodsChallengeNested TuplesChallengeWhat Is a Dictionary?ChallengeDictionary MethodsChallenge
5. Loops
while LoopChallengefor LoopChallengeRangeChallengeIterating Over IndexesNested Loops
6. Functions
Built-in FunctionsChallengeDefining Your First FunctionChallengeif/else Statements in FunctionsChallengeFunctions With No ReturnChallengeModifying FunctionsChallengeLambda FunctionsChallenge

bookMembership Operators and Types Comparison

So far, we've discussed the primary comparison operators commonly used for numbers and strings. Python also offers membership operators that allow you to determine if a certain sequence exists within an object.

In Python, sequence objects include strings, lists, tuples, and more. We'll delve into these in the next section.

The membership operators are in and not in. If the sequence exists within an object, the in operator will return True. For instance, let's see if the letter 'n' is in the word 'codefinity'.


              
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# Initial string
site = "codefinity"
# Using membership operator
print("n" in site)
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A True result indicates that the letter was found in the given word. Conversely, the not in operator checks if a certain sequence does not exist within an object. At times, we might need to verify whether an object is of a particular type. For instance, if we're writing a program to divide an input value by 2, we need to ensure the value is numerical; otherwise, the operation won't work. There are two methods to determine if a value is of a specific type:

  • One approach is to compare a variable's type to the desired type using the is operator. For instance, type(var) is int will return True only if the var variable's value is an integer;
  • Alternatively, you can use the isinstance() function. This function requires two arguments: the first is the value whose type you wish to verify, and the second is the type to compare against. For example, isinstance(var, int) will also return True only if the value in the var variable is an integer.

To illustrate, let's determine if 3.5 is an integer.


              
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# Initial number
num = 3.5
# Checking if num is an integer
print(type(num) is int) # the first approach
print(isinstance(num, int)) # the second approach
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As demonstrated, both methods returned False because 3.5 is a float and not an integer (int).

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Section 3. Chapter 5
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