Unit 1
1) The purpose of this Unit is to enhance migrants’ basic soft skills and competencies, which are needed in today’s labor market and help them in their fist steps while in search for a job.
2) The Unit includes four units, focusing on themes such as installing Python, working with variables, lists, while loop, arithmetic operations, generators in Python and other.
3) The main part of this presentation is the compilation of programmers with Python
4) The Unit aims at helping the reader to understand «Installing Python», «the interpreter», «create your first program» and «working with variables».
After completing the course you will attain a fundamental understanding of the Python programming language, object oriented programming base, essential skills to specialize on particular branches — machine learning, data science etc.
Python is a high-level (“human readable”) programming language that uses an interpreter to display results. Python contains an extensive standard library of tested code modules that can be easily incorporated into your own programs.
Developed by GuidovanRossum in the late 1980s and early 1990s at the National Research Institute of Mathematics and Computer Science in the Netherlands, Python is derived from many other languages, including C, C ++ and the Unix shell. Today Python is supported by the core team at the institute, although Guido vanRossum still plays an important role in determining the direction of the language. Code readability, making Python especially suitable for newbies to programming.
Because Python is focused on code readability, it often uses English keywords where other programming languages tend to use punctuation marks. A special difference is that Python uses indentation rather than keywords or punctuation marks to group statements in a block of code.
The Python interpreter processes your program’s textual code and also has an interactive mode, useful for debugging and testing snippets of code. Python interactive mode can be accessed in several ways:
Regardless of which method you choose to enter interactive mode, the Python interpreter will respond in the same way to commands entered on its command line after the >>> characters. In this mode, it can be used as a calculator.
The Python interpreter understands any arithmetic expression, so you can use parentheses to indicate the order of evaluation – the part of the expression enclosed in parentheses will be evaluated first.
3. Now on the Python command line, type the same expression, but add parentheses to indicate the order of evaluation.
In addition to being useful as a basic calculator, Python interactive mode can be used to create programs. A Python program is a plain text file created with a simple editor such as Notepad and saved as a .py file. You can run a Python program by specifying the name of the corresponding file after the python command in the interpreter command line. By tradition, the first program that is created when learning a programming language simply displays a message with a greeting. In Python, the print () function is used for this, the message for the output of this function is indicated in brackets. It can be a character string enclosed in quotation marks. Quotes can be double (“”) or single (”), but you cannot use both at the same time.
The procedure for creating your first Python program on Linux is no different from that on Windows. However, regardless of the platform you are using, you should always remember that if different versions of Python are installed, then the correct command should be used to invoke the interpreter. This is especially important for Linux systems, which usually come with the installed version of Python 2.7, and the typed python command invokes this interpreter by default. If Python 3.3 is installed and you want to call it to process your program, then you should use the python3.3 command to invoke the correct version of the interpreter.
In programming, a variable is a container in the computer’s memory where data is stored. After the data has been saved, it can be called using the name of this variable. The programmer can choose any name for the variable, except for Python keywords. It is best to choose meaningful names for variables that reflect their content.
In Python programs, data that needs to be stored in variables is entered using the assignment operator =, for example, to store the numeric value 8 in a variable named a, you would write: a = 8
You can then refer to the stored value of the variable using its name. Thus, the print (a) statement will print out the stored value 8. Variables can be sequentially assigned different values, and therefore a variable can take on different values as the program runs – it is no coincidence that it is called that: variable.
In Python, a variable must be assigned an initial value (variable initialization) in the statement that declares the variable in the program, otherwise the interpreter will raise the error notdefined (undefined variable).
In one statement, it is allowed to initialize several variables with the same value. This can be done using the assignment operator =. For example, to initialize variables a, b and c and assign them the value 8, we use the notation: a = b = c = 8
On the contrary, several variables can be initialized with different values and written all in one statement, using a comma as a separator. For example, as an initialization of variables a, b and c with numeric values 1, 2, 3 we use the notation: a, b, c = 1, 2, 3
Some programming languages, such as Java, require variable types to be specified when declaring them. In this case, a certain amount of memory is reserved. This technique is known as static typing. This restriction is not imposed on variables in Python, and memory is allocated in accordance with the values assigned to the variables (dynamic typing). This means that a variable can contain both integers and floating point numbers, text strings, or boolean values. You can add comments to your Python programs to describe instructions or sections of code. The # symbol is used for this. Anything after this character to the end of the line is ignored by the Python interpreter. Comments are very useful – they help make your code understandable for others, as well as for yourself when you come back to it later.
# Initialize the variable with an integer value
var = 8
print (var)
# Assign a floating point value to a variable
var = 3.142
print (var)
# Assign a string value to the variable
var = ‘Pythonineasysteps‘
print (var)
# Assign a boolean value to the variable
var = True
print (var)
Variables in Python can be assigned values not only through a program, but also through user input. The input () function is used for this. It takes a string as an argument, which will be displayed to the user, prompting him to enter data, and then reads the string entered by the user.
Such characters are interpreted as a text string, even if they are actually numeric values. This string can be assigned to any variable using the assignment operator =. Subsequently, you can work with this variable in the same way as with others, for example, display its value by specifying the variable name in the print () function.
Using the print () function, you can also print several values of variables by specifying them inside parentheses, separated by commas.
# Initialize the variable with the value entered by the user
user = input (‘I amPython. Whatisyourname?:’)
# Print the string and the value of the variable
print (‘Welcome’, user)
When you print multiple values using the print () function, they are separated by a single space by default. To specify an alternate separator, you can add the sep parameter to the print () function. For example, if you use sep = ‘*’, you will get values in the output, separated by *.
Also, by default, the print () function prints a non-displayable newline character (\ n) at the end of each line. But it is possible to specify your own symbol using the end parameter. For
example, using end = ‘!’ will print an exclamation mark at the end of each line.
user input prompt
# Initialize another variable with the value entered by the user
lang = input (‘Favorite programming language?:’)
# Print the string and the value of the variable
print (lang, ‘Is’, ‘Fun’, sep = ‘*’, end = ‘! \ n’)
Python is a high-level (“human readable”) programming language that uses an interpreter to display results. Python contains an extensive standard library of tested code modules that can be easily incorporated into your own programs.
Developed by GuidovanRossum in the late 1980s and early 1990s at the National Research Institute of Mathematics and Computer Science in the Netherlands, Python is derived from many other languages, including C, C ++ and the Unix shell. Today Python is supported by the core team at the institute, although Guido vanRossum still plays an important role in determining the direction of the language. Code readability, making Python especially suitable for newbies to programming.
Because Python is focused on code readability, it often uses English keywords where other programming languages tend to use punctuation marks. A special difference is that Python uses indentation rather than keywords or punctuation marks to group statements in a block of code.