python and data preprocessing Flashcards
Libraries in machine learning
1.Pandas-It is used for data manipulation and analysis and providing data structures.
2.Numpy-It is used for numerical computing in python.
3.Tensorflow-It is used for high performance numerical computation.
4.Matplotlib-It is is used for creating visualisation in Python.
5.Seaborn-It is also used for data visualizations.
6.Scipy-A library used for scientific and technical computing
7.Keras-It is used to implement neural networks.
Keywords
They are reserved words that can not be used as an identifier.eg.false.true,for,if.
Code for showing keywords
import keyword
print(keyword.kwlist)
len(keyword.kwlist)
Identifier
These are names given to entities like class,funtion,variables.They help differentiate one entity from one another.
Rules when writing identifiers
They can not start with a digit
They can not use special symbols
Keywords cannot be used as identifies
egp=156
if p==156:
print(p)
Comments
Single line comments-#
Multiple line comments-‘’’
Variable
Is a reserved memory location that is used to store a value
x=5
id(x)
ID function
It returns the identity of the object.
The identity of an object is defined in three aspects:
1.As an integer or any other data type.
2.It is guaranteed to be unique.
Data types
Strings
Integers
Floats
Double
Boolean
Docstring
It provides a way of associating documentation with funtions,clases,methods or modules
List
It is an ordered sequence of items
All method-all()
All method returns true if all elements in a list is true but false if all elements are false
Tuples
It is like a list but the elements cannot be changed once the values are assigned ie immutable
It can contain a mix of data types
Sets
They are a collection of items
they are unique,immutable and the set itself is mutable ie can add or remove items
Add & Remove Items
myset.add(‘NINE’) # Add item to a set using add() method
myset
myset.remove(‘NINE’) # remove item in a set using remove() method
myset
Union of sets
A = {1,2,3,4,5}
B = {4,5,6,7,8}
C = {8,9,10}
A|B # Union of A and B (All elements from both sets. NO DUPLICATES)
Dictionary
is a mutable data type in Python.
A python dictionary is a collection of key and value pairs separated by a colon (:) & enclosed
in curly braces {}.
Keys must be unique in a dictionary, duplicate values are allowed.
egmydict = {1:’one’ , 2:’two’ , 3:’three’} # dictionary with integer keys
mydict
Operators
Operators are special symbols in Python which are used to perform operations on variables/values.
eg arithmetic,logic,comparison
Functions
A function is a block of organized code written to carry out a specified task
Information onfunctions
1.Functions help break our program into smaller chunks for better readability.
2.Information can be passed into a function as arguments.
3.Parameters are specified after the function name inside the parentheses.
4.We can add as many parameters as we want. 5.Parameters must be separated with a comma.
6.A function may or may not return data.
7.In Python a function is defined using the def keyword
Parameter VS Argument
A parameter is the variable listed inside the parentheses in the function definition while
An argument is the value that is sent to the function when it is called.
Types of functions
Built-in function :- predefined functions that are readily available for use like sum() , print()
User-Defined Functions:- Function that we define ourselves to perform a specific task.
Anonymous functions : Function that is defined without a name. Are
also called as lambda functions. They are not declared with the def keyword
Function syntax
FunctionName(parameters):
statements(s)
return[expression]
example
def myfunc():
print(“Hello Python Lovers”)
myfunc()
Class
Is a blueprint for creating objects
Objects
Is an encapsulation of variables and functions
