Python Notes Unit 1, Part 2
UNIT – 1(part 2)
Introduction to Python
History and its Features
Basic Syntax
Understanding Python variables
Numeric data types
Using string data type and string operations
Basic Operators
Understanding coding blocks.
Defining list and list slicing,
Other Data Types- Tuples. List, Python Dictionary, Arrays, Associative Arrays/Hashes
Data types: -
1. The
type of variable present in our code is represented by Data Types.
2. A
data type is the classification of data items.
3. Data
type represents the kind of value that tell what operation can perform on
particular code.
4. Various type of data types that define the storage method on each of them.
Numeric
data type -
In
python, three types of numeric data types
1. Integer
2. Float
3. Complex
number
Mainly two types
of numeric data types are used in code.
Integer or float.
Numeric data type represents the data that has
a numeric value. This numeric value can be integer, float and complex number.
These values are defined as int, float and complex classes.
For
example – int data type
a=5
print (“the type of a”, type(a))
Output
– The type of a <class ‘int’ >
For
example – float datatype
a = 4.5
print (“the type of b”, type(b))
Output – The type of b <class ‘float’
>
Dictionary data type –
1. Dictionary
data type are working as hash table type.
2. In
dictionary data type each key are stored and indicate different value at
searching time.
Boolean data type:
-
1. Boolean
data type is also a type of one of the built-in data types.
2. This
data type is representing one of the two values.
a. Either
TRUE
b. Or
FALSE
3. Boolean
data type is also a logical data type than can have only the values.
4. True
and False are also used as keywords.
5. The
keyword True and False must an Upper Case first letter if we are using
lowercase true return an error.
Example –
print(True)
print(type(True))
print(False)
print(type(False))
Output –
True
<class ‘bool’>
False
<class ‘bool’>
Set data type: -
1.
A set data type is
collection which is unordered, unchangeable
and unindexed.
2.
Set is defined by comma
inside braces { }.
3.
Items under the set are
not ordered.
Example –
a = {5, 2, 3, 1, 4}
print (“a = “, a)
print(type(a))
Output -
a= {1, 2, 3, 4, 5}
<class ‘set’>
Sequence type data type -
1. Sequence
type data type is used to store data in containers.
2. List,
Tuple and String are the different types of
containers in python programming language.
String: -
1. A
string is generally considered as a data type and is often implemented as an
array data structure of bytes that stores a sequence of elements, typically
characters, using some character encoding.
2. Strings
are sequences of character data.
3. The
string type in Python is called str.
4. String
can be considered as a special type of sequence, where all its elements are characters.
For example- string “Hello, World” is
basically in sequence
[‘H’,’E’,’L’,’L’,’O’,’’,, ‘ ’,’W’,’O’,’R’,’l’,’d’]
Declaration
of strings: -
>>> mystring =
“This is not my first copy”
>>> print (mystring);
This is not my first
copy
List –
1. The
list data type is a versatile data type.
2. In
Python is list can simultaneously hold different types of data.
3. Formally
list is an ordered sequence.
4. Defining
a list in python is easy – just use the brackets syntax to indicate items in a
list.
List_of_ints= [1, 2, 3]
5. Items
in a list do not have to all be the same type, either. They can be any python
object.
Tuple –
1. The
tuple data type is the same as List Datatype except that it is immutable, that
means once we create any tuple, you cannot make any changes to that.
2. The
tuple is a Read-only version of List, which means we cannot add, remove and
replace any elements.
The syntax for the Tuple is –
Tuple=(Elements)
Example-
Tuple= (10,20,30,
“banana”)
Print(type(Tuple))
Output
- <class ‘tuple’>
List Slicing
1. List
Slicing refers to accessing a specific portion of a subset of the list for some
operation while the original list remains unaffected.
2. The
slicing operator in python can take three parameters out of which two are
optional depending on the requirement.
Syntax
of list slicing:
List_name [start:stop:steps]
3. The
start parameter is a mandatory
parameter, whereas the stop and
steps are both optional parameters.
a. The
start represents the index from
where the list slicing is supposed to begin. Its default value is 0, it begins
from index 0.
b. The stop represents the last index up to
which the list slicing will go on. Its default value is (length(list)-1) or the
index of last element in the list.
c. The
step represents the number of steps,
i.e after every n number of steps, the start index is updated and list slicing
is performed on that index, or in simple words, steps if defined, specifies the
number of elements to jump over while
counting from start to stop.
This means we can
do list slicing in three ways:
1. By
passing just the start or stop parameter
2. By
passing the start and stop parameter.
3. By
passing the start, stop and steps parameters.
Next Part is coming soon..!! keep study and keep growing
