This is a repository only for learning python and automate boring stuff in daily life.
You'll remember the things you do much better than the things you only read.
- 2 + 2
Expressions consist of values (such as 2) and operators (such as +), and they can evaluate down to a single value.
The ** operator is evaluated first; the *, /, //, and % are evaluted next, from left to right; and the + and - operators are evaluated last (also from left to right). You can use parentheses to override the usual precedence if you need to.
- A data type is a category for values, and every value belongs to exactly one data type.
- The integer (or int) data type indicates values that are whole numbers.
- Numbers with a decimal point, such as 3.14 are called floating point numbers (or floats).
- Always surround your string in single quote (')
- You can even have a string with no characters in it. '' called a blank string.
- + is the addition operator when it operates on two integers or floating-point values. However, when + is used on two string values, it joins the strings as the string concatenation operator.
- The * operator is used for multiplication when it operates on two integer or floating point values.But when the * operator is used on one string value and one integer value, it becomes the string replication operator.
- A variable is like a box in the computer's memory where you can store a single value.
- If you want to use the result of an evaluated expression later in your program, you can save it inside a variable.
- Assignment Statements
- You'll store values in variables with an assignment statement. An assignment statement consists of a variable name, an equal sign (called the assignment operator), and the value to be stored.
- If you enter the assignment statement spam = 42, then a variable named spam will have the integer value 42 stored in it.
- Packages are nothing more than a folder of Python module files.
- In the package folder, a file named init.py should be present,it can be empty
- This file can be used for package initialization
- When Python sees this file, it treats the folder as a package, and it modules can be imported
- The folder name is the package name, and can be thought of as a namespace
- The Python Package Index is the official public package repository for Python.
- The packages are simply shared code libraries which save developers lots of time by not requiring them to reinvent the wheel for each task they need to accomplish.
- To use the repository to download and install packages, the program pip is used.
- Pip is distributed with Python.
- https://pypi.python.org/pypi
- Packages can be installed globally or for the user.
- To install a package globally, open a terminal, and run the following command:
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pip install <package name>
- To install the package for the current user only, run the following command:
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pip install --user <package name>
- To remove a package run:
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pip uninstall <package name>
- If a package is installed locally (with --user) and globally, the local version will be installed first.
- Run the command again to uninstall the package globally.
- To list all installed packages:
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pip list
- To see a list of outdated packages:
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pip list --outdated
- To upgrade a package:
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pip install --upgrade <package name>
- To see more details of a package:
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pip show <package name>
- To ensure packages are installed for a given application, a "requirements.txt" can be created.
- To initially create the "requirements.txt" file, the pip "freeze" command can be used
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pip freeze > requirements.txt
- The "requirements.txt" can be used by pip to install the packages listed inside of it
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pip install -r requirements.txt