2. What we learnt this week ?
Sequence Data Types
Strings
Lists
Tuple
Dictionary
Sets
Numpy
3. What are Sequence Data Types ?
Sequence Data Types allows us to store multiple values in an organized and
efficient fashion.
String, List, Tuple are some example of Sequential types
Dictionaries and Sets are container for Non-sequential data.
4. Strings
String is an immutable sequence data type.
Immutable – which can’t be changed
It is the sequence of Unicode characters wrapped inside single, double, or triple
quotes.
Example:
‘This is a string in Python’
“This is a ‘string’ in Python”
‘“This is a “string” in Python”’
5. Functions/Methods on String
string*n - repeats the given string n times
upper() - Converts a string into upper case
lower() - Converts a string into lower case
split() - Splits the string at the specified separator, and returns a list
index() - Searches the string for a specified value and returns the position of where it is
found
count() - Returns the number of times a specified value occurs in a string
capitalize() – Returns the string with its first character capitalized and the rest lowercased
6. Lists
A list is an ordered and mutable Python container.
Lists are used to store multiple items in a single variable.
Lists are created using square brackets
Example:
myList = [1 , 2 , 3 , 4 , 5]
myList = [1 , ‘two’ , 3 , ‘four’ , 5]
myList = [1 , [‘a’ , ‘b’ , ‘c’] , ‘hello’]
7. Functions/Methods on Lists
append() - Adds an element at the end of the list
pop() - Removes the element at the specified position
clear() - Removes all the elements from the list
insert() - Adds an element at the specified position
reverse() - Reverses the order of the list
extend() - Add the elements of a list (or any iterable), to the end of the current list
8. Dictionary
Used to store data values in key:value pairs.
Dictionaries are written with curly brackets, and have keys and values
Syntax:-
{'key1':'value1','key2':'value2'}
Duplicates not Allowed
Dictionaries cannot have two items with the same key.
Example
mydictionary = {
"brand": "Ford",
"model": "Mustang",
"year": 1964
}
9. Numpy and Numpy Array
Numpy is a Python package and it stands for numerical python.
A numpy array is a grid of values, all of the same type.
To install numpy on your system, run this command on your CMD
pip install numpy
To create numpy array, we first need to import the numpy package:
import numpy as np
Example:-
array = np.array([1,2,3,4,5], dtype = int )
10. Methods/Functions
type(array) – this will give you the Datatype of Array
len(array) – length of array
array.ndim - return the number of dimensions of an array
array.shape - returns a tuple with each index having the number of
corresponding elements
array.reshape – it changes the shape of the array
