essyy / python-leaning---

python-leaning---

• A virtual environment is a sandbox where you can install only the Python packages you need for a particular project, without the risk of those packages clashing with those for another project (or your system). You create different little sandboxes for each project and install only the packages you want in it.
• theoce is python3 -m ❶ venv ❷ venv
• The first venv ❶ is a command that creates a virtual environment, and the second venv ❷ is the desired path to the virtual environment. In this case, venv is just a relative path, creating a venv/ directory in the current working directory. However, you could also use an absolute path, and you could call it whatever you want. For example, you could create a virtual environment called myvirtualenv in the /opt directory of a UNIX system, like this
• python3 -m venv /opt/myvirtualenv
• to activate it venv\Scripts\activate.bat
• Pip is used in installation of files using the command: pip install
• You can use == to signify a specific version or even >=
• You can also write a requirements.txt filr that contains commands of packages yu would like to install
• Then run pip install -r requirements.txt

Update files using pip install --upgrade---------------

pip search command to find the packages

** Concatenation of strings it can be done 'This costs' + str(6)+ 'dollars'

"Myname is" + "Hello:Nick:World".split(":")[1] 'Myname is Nick' Boolean Operators List is arranged in the form of arrays. Thy are still arranged in the same order index 0,1,... etc Dictionaries are written using the {} {"name": "Nick", "age":27, "hobby":"code"} ["name"] to retrieve the values, you use the []

• Variable - they enable the reuse of variables, also in writing functions it is essential
• variables can be written using camelcase - myVariableName = "John", pascal case - MyVariableName = "John" and snake case-- my_variable_name = "John"

There are two types of variables in a function: Local variable and local variable Then in printing thr int and string, use a comma instead of a + data type Text Type: str Numeric Types: int, float, complex Sequence Types: list, tuple, range Mapping Type: dict Set Types: set, frozenset Boolean Type: bool Binary Types: bytes, bytearray, memoryview None Type: NoneType

in strings, You can use quotes inside a string, as long as they don't match the quotes surrounding the string: example; print("He is called 'Johnny'")

in modifying strings

• The upper() method returns the string in upper case:
• The lower() method returns the string in lower case
• The strip() method removes any whitespace from the beginning or the end:
• The replace() method replaces a string with another string:
• The split() method splits the string into substrings if it finds instances of the separator: -Example: age = 36 txt = f"My name is John, I am {age}" print(txt) the curly braces {} are used for a placeholder A modifier is included by adding a colon : followed by a legal formatting type, like .2f which means fixed point number with 2 decimals:

• use of f strings

• To specify a string as an f-string, simply put an f in front of the string literal, and add curly brackets {} as placeholders for variables and other operations.

eSCAPE CHAR

To insert characters that are illegal in a string, use an escape character.

An escape character is a backslash \ followed by the character you want to insert. txt = "We are the so-called "Vikings" from the north."

Built in functions - leng, bool, int, float, sorted

sorted([12, 23, 45, 6, 7, 8, 9 , 754]) [6, 7, 8, 9, 12, 23, 45, 754]

• User defined functions in defining functions, use smallcase letters, capitalization of each alphabet is used in OOP

Examples of functions

def my_function(): print("This is my function!") print("A second String")

my_function() Function 2 def print_something(name = "Someone",age = "Unknown"): print("My name is ",name, "and my age is", age)

print_something("nick")

Ininfite values def print_people(*people): for person in people: print("This person is", person)

print_people("Nick", "Dan", "Jack")

List is a collection which is ordered and changeable. Allows duplicate members. Tuple is a collection which is ordered and unchangeable. Allows duplicate members. Set is a collection which is unordered, unchangeable*, and unindexed. No duplicate members. Dictionary is a collection which is ordered** and changeable. No duplicate members.

** Method Description fOR lists append() Adds an element at the end of the list clear() Removes all the elements from the list copy() Returns a copy of the list count() Returns the number of elements with the specified value extend() Add the elements of a list (or any iterable), to the end of the current list index() Returns the index of the first element with the specified value insert() Adds an element at the specified position pop() Removes the element at the specified position remove() Removes the item with the specified value reverse() Reverses the order of the list sort() Sorts the list