Course Content
Introduction to Python
Introduction to Python
2. Variables and Types in Python
How to Store Numbers in PythonPython Naming Rules for VariablesHow to Work with Variables in PythonData Types in PythonChallenge: Converting Kilometers to MilesStore Text with Strings in PythonString Indexing in PythonNegative Indexing and String Length in PythonString Slicing in PythonChallenge: Retrieving Letters from StringString Concatenation in Python
3. Conditional Statements in Python
Boolean Data Type in PythonChallenge: Working with Comparison OperatorsHow to Combine Conditions in PythonChallenge: Working with Logical OperatorsMembership Operators and Type Comparisons in PythonHow to Use if/else Expressions in PythonChallenge: Running a Grocery StoreChallenge: Creating Odd and Even Logicif/elif/else ExpressionsChallenge: Running Grocery Store ExtendedChallenge: Outputting Positive, Negative or Zero
4. Other Data Types in Python
Python ListsCommon List Methods in PythonChallenge: Updating ListNested Lists in PythonChallenge: Retrieving Information from Nested ListPython TuplesCommon Tuple Methods in PythonChallenge: Updating TupleNested Tuples in PythonChallenge: Retrieving Information from Nested TuplePython DictionariesChallenge: Completing DictionaryCommon Dictionary Methods in PythonChallenge: Updating Dictionary
6. Functions in Python
Built-in Functions in PythonChallenge: Converting HeightsHow to Create Functions in PythonsChallenge: Writing First FunctionUse of if/else Statements in Python FunctionsChallenge: Identifying Positive Values Functions Without Return in PythonChallenge: Creating Logging FunctionModifying Functions in PythonChallenge: Updating Logic of the FunctionLambda Functions in PythonChallenge: Creating Lambda Function
Common Dictionary Methods in Python
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 ofkey:value
pairs in the dictionaryd
;d.copy()
- creates a copy of the dictionaryd
;d.items()
- provides all thekey, value
pairs from the dictionaryd
;d.keys()
- lists all the keys in the dictionaryd
;d.values()
- provides all the values from the dictionaryd
.
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:
# Initial dictionary countries_dict = {'USA': (9629091, 331002651), 'Canada': (9984670, 37742154), 'Germany': (357114, 83783942)} # Update dictionary with two countries countries_dict["Brazil"] = (8515767, 212559417) countries_dict["India"] = (3166391, 1380004385) print(countries_dict)
Everything was clear?
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Section 4. Chapter 13