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Python for Novices Cheat Sheet (DRAFT) by

Python Cheat Sheet for beginners

This is a draft cheat sheet. It is a work in progress and is not finished yet.

TOPIC 01: INTROD­UCTION

 
- Python Introd­uction
- Getting Started
- Keywords & Identi­fiers
- Statements & Comments
- Python Variables
- Python Datatypes
- Python Type Conversion
- Python I/O and Import
- Python Operators
- Python Namespace

1.1. Install Thonny Python IDE

Link to download Thonny Python IDE for beginners
Thonny is a popular Python Integrated Develo­pment Enviro­nment (IDE) that is designed for beginners and students learning to program in Python.

1.2. Run Thorny Python IDE

Thonny comes with Python 3.10 built in, so just one simple installer is needed and you're ready to learn progra­mming. (You can also use a separate Python instal­lation, if necess­ary.) The initial user interface is stripped of all features that may distract beginners.

1.3. Python Progra­mming Keywords

False
class
finally
is
return
None
continue
for
lambda
try
True
def
from
nonlocal
while
and
del
global
not
with
as
elif
if
or
yield
assert
else
import
pass
break
except
in
raise
In Python, All keywords are case sensitive. All the keywords except True, False and None are in lowercase and they must be written as it is.

1.4. Create a program to test Keywords

>>> import keyword
>>> keyword.iskeyword("tutsmake.com")
False
>>> keyword.iskeyword("try")
True
>>>

1.5. Python Progra­mming identi­fiers

Identifier rules of Python
Rule 1:
Use either a lowercase (A to Z) or an uppercase (A to Z) sequence of letters. However, you can also add digits (0 to 9) or an underscore (_) while writing identity in python.
 
For example:- Names like myClass, my_1, and upload­_im­age­_to_db are all valid identi­fiers.
Rule 2:
You cannot write digit with the start of an identi­fier. This will assume invalid. But you can write digit with the end of the identi­fier.
 
For Example:- If you write identifier like 1variable, it is invalid, but variable1 is perfectly fine.
Rule 3:
Python Progra­mming Reserved Keywords cannot be used as identi­fiers. Like del, global, not, with, as, if, etc.
Rule 4:
Also, you can not use special character as an identifier in python progra­mming like ‘.’, ‘!’, ‘@’, ‘#’, ‘$’, ‘%’ , etc.
Rule 5:
The identifier can be of any length.
In the Python progra­mming language, identi­fiers are user-d­efined names. Which represents functions, classes, variables, and any other objects in the code. It helps to distin­guish one identity from another.

1.6. Create a program to test identifier

>>> 'jonh'.isidentifier()
True
>>> '1hello'.isidentifier()
False
>>> 'tutsmake.com'.isidentifier()
False
>>> 'tutsmake_com'.isidentifier()
True

1.7. Python Statement

Simple Assignment Statement
Syntax:
variable = expression
Example:
lang = "­Learn Python­"
Multi-line statement
Use a new line character to break the statement line
x = 5 + 4 + 2 + \ 
     1 + 6 + 4 + \
     9 + 7 + 8
Use parent­heses ( ), brackets [ ] and braces { }.
x = (5 + 4 + 2 +
     1 + 6 + 4 +
     9 + 7 + 8)
  
colors = ['red',
          'blue',
          'green']
Multiple line statements in signle line.
Use semicolons
a = 1; b = 2; c = 3
In python progra­mming, A statement is a logical instru­ction. Which can read and execute by Python interp­reter. In Python, it could be an expression or an assignment statement.

1.8. Python Indent­ation

Python uses indent­ation
A code block starts with indent­ation and ends with the first unindented line. And a code block that represents the body of a function, loop, etc. For example:
  
for i in range(1,9):
     print(i)
     if i == 5:
         break
Python Comments
Single line comment
  
#This is hello world by tutsmake.com
 print(­'Hello world')
Multi line comment
  
#This is hello world program
 #by tutsmake.com{{nl #hello{{nl print(­'Hello world'
  
"­"­"This is also a
     multi line
     comments"""
 print(­'Hello world')

1.9. Docstring in Python

Docstring in Python
  
def myFunc(no):
     "­"­"­Fun­ction to 10x the value"""
     return 10*no
access the code above
  
>>> print(­myF­unc.__­doc__)

1.10. Python Variable and Type

Rules for creating a variable in python
Rule 1:
A variable name must begin with a letter or the underscore character
Rule 2:
A variable name cannot begin with a number
Rule 3:
The python variable name can only contain alpha-­numeric characters and unders­cores (A-z, 0-9, and _ )
Rule 4:
A Variable names are case-s­ens­itive Like name, Name and NAME are three different variables
Python declar­e/c­reate variable
Here first we will create­/de­clare a variable. And also assign value to it.
x = 10
print("My fav no is " + x)
Change variable value in python
We will create a variable and change the value of this variable at runtime.
x = 10
print("My fav no is " + x)
x = 15
print("My fav no is " + x)
Assigning a single value to multiple variables
Python allows to assign a single value to several variables simult­ane­ously.
x = y = z = 10
print(x)
print(y)
print(z)
Assigning a different values to multiple variables
x, y, z = 5, "­str­ing­", 99  
print(x)  
print(y)  
print(z)
Types of variables
Local Variable
Which variables are made inside the function. They are called local variables. Local variables can be used only inside the function. For example:
  
  def valfun():
    x = "great"
    print(­"­Python is " + x)
  valfun()
Global Variable
Which variables are made outside the function. They are called global variables. Global variables can be used both inside and outside the function. For example:
  
 x = "great"
  def valfun():
    print(­"­Python is " + x)
  valfun()

1.11. Data Types in Python

Numbers Data Type
Integer, floati­ng-­point numbers, and complex numbers under the category of Python numbers. Those you define as int, float and complex classes. For example:
 a = 10
 print(a, "is of type", type(a))

 a = 50.0
 print(a, "is of type", type(a))

 a = 11+2j
 print(a, "is complex number­?", isinst­anc­e(1­1+2­j,c­omp­lex))
Output of the above program is following:
 10 is of type <class 'int'>
 50.0 is of type <class 'float'>
 (11+2j) is complex number? True
List Data Type
list data types hold different types of data. it does not need to be of the same type. The items stored in the list are separated with a comma (,) and enclosed within square brackets [].
 a = [10, 5.5, 'python'] 
 print(a) 
 a = [5,10,­15,­20,­25,­30,­35,40] 
 # a[2] = 15 
 print(­"a[2] = ", a[2]) 
 # a[0:3] = [5, 10, 15] 
 print(­"­a[0:3] = ", a[0:3]) 
 # a[5:] = [30, 35, 40] 
 print(­"­a[5:] = ", a[5:])
The output of the above program is following:
 [10, 5.5, 'python']
 a[2] =  15
 a[0:3] =  [5, 10, 15]
 a[5:] =  [30, 35, 40]
Tuple Data Type
A tuples data type is alike to list data type. But it is only one differ­ence, once tuples created can not be change­d/m­odify.
Tuples contain the collection of the items of different data types alike list data type. The items of the tuple are separated with a comma (,) and enclosed in parent­heses ().
 a = (8,'py­thon', 1+2j) 
 # a[1] = 'program' 
 print(­"a[1] = ", a[1]) 
 # a[0:3] = (5, 'program', (1+3j)) 
 print(­"­a[0:3] = ", a[0:3])
Output of the above code is following:
 a[1] =  python 
 a[0:3] =  (8, 'python', (1+2j))
Strings Data Type
A string is a sequence of characters in Python. In python, Strings are either enclosed with single quotes, double, and triple quotes.
 string = 'Hello world!' 
 # string[1] = 'e' 
 print(­"­str­ing[1] = ", string[1]) 
 mString = "­"­"­Hello world! 
               this is multi 
               line string exampl­e""" 
 print(­mSt­ring)
Output of the above program is the following:
 string[1] =  e 
 Hello world! 
               this is multi  
               line string example
Set Data Type
Set data types hold unordered collection of unique items. The items stored in the set data types are separated with a comma (,) and enclosed within square brackets { }.
 abc = {5,2,3­,1,4} 
 # printing set variable 
 print(­"abc = ", abc) 
 # data type of variable a 
 print(­typ­e(abc))
Output of the above program is following:
 abc =  {1, 2, 3, 4, 5}
 <class 'set'>
Dictionary Data Type
Dictionary data types is held data in key and value pairs. Note:- A dictionary data type does not allow duplicate keys in collec­tion. But the values ​​can be duplicate. For example:
 dict = {1:"­joh­n","l­ast­nam­e":"s­mit­h", "­age­":25} 
 # prints the value where key value is 1 
 print(­dic­t[1]) 
 # prints the value where key value is "­las­tna­me" 
 print(­dic­t["l­ast­nam­e"]) 
 # prints the value where key value is "­age­" 
 print(­dic­t["a­ge"])
Output of the above program is following:
john smith 25
 

TOPIC: FLOW CONTROL

 

TOPIC: FUNCTIONS

 

TOPIC: DATATYPES

 

TOPIC: FILE HANDLING

 
- File Handling Operation
- Python open and close
- Python Read and Write
- Python File Delete

TOPIC: Python built-in Methods

 
- Math Functions
- Math Module Functions
- String Methods
- List Methods
- Dictionary Methods
- Set Methods