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Introduction to Python

Dictionary Methods

As you've probably noticed, dictionaries have unique characteristics that set them apart from lists and tuples. They also come with their own set of methods. Let's dive in.

  • len(d) - returns the number of key:value pairs in the dictionary d;
  • d.copy() - creates a copy of the dictionary d;
  • d.items() - provides all the key, value pairs from the dictionary d;
  • d.keys() - lists all the keys in the dictionary d;
  • d.values() - provides all the values from the dictionary d.

Wondering how to add new entries to a dictionary? Dictionaries don't utilize list methods like .append() or .extend(), and they don't support concatenation like strings. Instead, since dictionaries organize data in key-value pairs, you simply assign values using keys:

d[k] = e - assigns the value e to the key k. If the key k already exists in the dictionary, its associated value will be updated.

For example, let's add a couple of countries to our dictionary:

Everything was clear?

Section 4. Chapter 13
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

Dictionary Methods

As you've probably noticed, dictionaries have unique characteristics that set them apart from lists and tuples. They also come with their own set of methods. Let's dive in.

  • len(d) - returns the number of key:value pairs in the dictionary d;
  • d.copy() - creates a copy of the dictionary d;
  • d.items() - provides all the key, value pairs from the dictionary d;
  • d.keys() - lists all the keys in the dictionary d;
  • d.values() - provides all the values from the dictionary d.

Wondering how to add new entries to a dictionary? Dictionaries don't utilize list methods like .append() or .extend(), and they don't support concatenation like strings. Instead, since dictionaries organize data in key-value pairs, you simply assign values using keys:

d[k] = e - assigns the value e to the key k. If the key k already exists in the dictionary, its associated value will be updated.

For example, let's add a couple of countries to our dictionary:

Everything was clear?

Section 4. Chapter 13
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