Aaa ped-2- Python: Basics

Python:
Basics (in Python)
AAA-Python Edition

Plan
●
1- Basic Operations and variables
●
2- Basic Types
●
3- Functions and white space formatting
●
4- Modules and Libraries
●
5- Examples of some Libraries
●
6- Installing Libraries in Google Colab

3
1-BasicOperations
Andvariables
[By Amina Delali]
●
To perform simple operations, you just have to type them:
Integer division/floored quotient
Modulus (remainder)
Exponent

4
1-BasicOperations
Andvariables
[By Amina Delali]
●
Other type of operations:
If 5 wasn’t greater
than 3, it would returned
False
Is 5 different
from 3
Is 5 equal to 3
The only case this expression is evaluated to False,
it’s when the two operands are evaluated to False
The only case this expression is evaluated to True,
it’s when the two operands are evaluated to True

5
1-BasicOperations
Andvariables
[By Amina Delali]
●
Table of precedence of some operators (increasing order)
To evaluate an expression with multiple operators,the “precedence” rule apply
Expression between parentheses is evaluated first:(-1+1)=0
Then the exponentiation is evaluated: 6**0=1
Then the multiplication is evaluated: 3*1=3
Then the addition is evaluated: 5+3=8
The full table can be seen at:
https://docs.python.org/3.6/reference/expressions.html#operator-precedence
or
and
not
< , <= , > ,
>= , != , ==
+, -
* , / , // , %
**
( )
Highest precedence
Operators in the same box
have same precedence
Operators in the same box group from left to right
(except for exponentiation **).For example, to evaluate 5 / 4 * 2 :
We start by: 5 / 4 = 1.25 (the most left operator)
Then: 1.25 * 2 = 2.5 (we continue with the following one)

6
1-BasicOperations
Andvariables
[By Amina Delali]
●
We can store values of expressions in “variables” with the
“assignment” statement:
Assignment statement
Variable name
●
Variable names have some mandatory characteristics
●
Composed of 1 word
●
Composed only by: letters, number or the
underscore character (_)
●
Can not start with a number
The value of “a” is 3,
and the value of “b” is 5

7
1-BasicOperations
Andvariables
[By Amina Delali]
●
We can assign one value to multiple variables
●
We can assign multiple values to multiples variables:

8
2-BasicTypes
[By Amina Delali]
● Numbers
●
Integer 5
-3
0
1000
●
Float 7.8
-3.156
0.0
●
Complex 5.3+2j
10+1J
●
A number can be:
Real part
Imaginary part

9
2-BasicTypes
[By Amina Delali]
Strings
●
String are text values written between quotes:

10
2-BasicTypes
[By Amina Delali]
Strings
●
With Strings, we can perform Concatenation and
Replication operations:

11
2-BasicTypes
[By Amina Delali]
●
Boolean
●
They have only two values: True and False
●
In a numeric context: True behaves like 1 and False like 0
●
The Boolean operators are : and, or, not

12
3-Functionsand
whitespace
formatting
[By Amina Delali]
●
Functions are a “reusable” block of code.
●
They can be “built-in” functions: already defned
●
They can be also “user-defned”: you can defne your own
functions.
●
Example of built-in functions:
Functions
Number of character of
string S1

13
3-Functionsand
whitespace
formatting
[By Amina Delali]
Functions
Convert j into a float
New line character

14
3-Functionsand
whitespace
formatting
[By Amina Delali]
User defined functions
White space formatting
●
Python uses indentation to define blocks of code
●
Blocks begin when the indentation increases
●
Blocks end when the indentation decreases
●
Whitespace is ignored inside parentheses and brackets
The block of code
is marked by a colon(:)
and its indentation
(the space before print)
Calling the function
(decreasing the indentation to terminate
The function definition block)

15
3-Functionsand
whitespace
formatting
[By Amina Delali]
●
Return statement
The function arguments
Keyword and default arguments
●
A function can return a value using the keyword “return”
The function returns the value
of a+b
●
In a function call, we can identify the arguments by their name.
●
In a function definition, the arguments can have a default value
they will be optional

16
3-Functionsand
whitespace
formatting
[By Amina Delali]
●
The default value of a third argument
So the argument is optional
The order of the arguments a and b
doesn’t matter, since they are identified
by their names

17
4-ModulesandLibraries
[By Amina Delali]
●
A module is a program that contains a related group of functions that can
be embedded in your programs
Module and Library
●
To use the functions module you have to use the “import” statement.
●
Other statement with import like “from” and “as” can be used
●
A set of modules define a Library
●
Python comes with a library called the standard library
●
To use an other library modules, you have to install the corresponding
library : a third-party library

18
4-ModulesandLibraries
[By Amina Delali]
Function “randint “from
module random
Only “randint” was
imported
The name of “randint” was replaced by “ri”

19
5-Examplesofsome
Libraries
[By Amina Delali]
● Third-party libraries
●
Numpy: is the fundamental package for scientific computing with
Python
●
Pandas: is an open source, BSD-licensed library providing high-
performance, easy-to-use data structures and data analysis tools for the
Python programming language.
●
Matpolotlib: is a Python 2D plotting library
●
Tensorflow: An open source machine learning framework for
everyone. It is a software library for high performance numerical
computation.

20
5-Examplesofsome
Libraries
[By Amina Delali]
●
Third-party libraries
●
Numpy:

21
5-Examplesofsome
Libraries
[By Amina Delali]
●
Third-party libraries
●
Matplotlib:

22
6-InstallingLibraries
inGoogleColab
[By Amina Delali]
! pip install
apt-get
After !apt-get update
From:( https://colab.research.google.com/notebooks/snippets/importing_libraries.ipynb)

References
●
Duchesnay Edouard and Löfstedt Tommy.Statistics and machine learning in python
release 0.2. On-line at ftp:
//ftp.cea.fr/pub/unati/people/educhesnay/pystatml/M1_IMSV/
StatisticsMachineLearningPythonDraft.pdf. Accessed on 23-09-2018.
●
Python Software Foundation. The python language reference. On-line
at https://docs.python.org/3.6/reference/index.html. Accessed on 23-09-2018.
●
Python Software Foundation. The python standard library. On-line at
●
https://docs.python.org/3.6/library/index.html. Accessed on 23-09-2018.
●
Joel Grus. Data science from scratch: frst principles with python. O’Reilly Media,
Inc, 2015.
●
J. D. Hunter. Matplotlib: A 2d graphics environment. Computing In Science &
Engineering, 9(3):90–95, 2007.
●
NumPy. Numpy. On-line at http://www.numpy.org/. Accessed on 23-09-2018.

References
●
pandas. pandas. On-line at https://pandas.pydata.org/. Accessed on
23-09-2018.
●
Chandat Sunny. Learn Python in 24 Hours. CreateSpace Independent
Publishing Platform, 2016.
●
Al Sweigart. Automate the boring stuf with Python: practical programming
for total beginners. No Starch Press, 2015.
●
TensorFlow. About tensorfow. On-line at https://www.tensorfow.
org/. Accessed on 23-09-2018.

RuleN°7
Thank
you!
FOR ALL YOUR TIME

Aaa ped-2- Python: Basics

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