2.strings lists

Strings

Collection of Characters

Popular string methods

Methods Description
len(string) to know the length of the string.
string[index] to get specific character from the string.
string[start:end] to get the group of characters from start index position to end index position of string.
string[start:end:step] to get the group of characters from start index position to end index position of string based on the step size. By default step size will be 1
string[::-1] reverses the string.
string.upper() coverts the string characters to upper case.
string.lower() converts the string characters to lower case.
string.split() to split the string, by default split function splits the string based on white space.
string.split(character) to split the string based on a specific character

Lists

Collection of objects

mylist = [1, 2.3, 'Hi']

nestedlist = [1, 2.3, 'Hi', [1, 2]]

List Slicing

  • can get the elements of a list using index.
  • Index starts with 0.
  • to select first element of a list
    mylist[0]
  • to get the elements from the end of the list, like to get last element,
    mylist[-1] or mylist[2] we will use negative number to start the cursor from end.

  • To select multiple elements from list.
    mylist[start, end]
    The start index will be included, while the end index is not.
    mylist[start:end:step]
    step indicates the step size between the elements

Example

mylist = [1, 2, 3, 4, 5, 6, 7]
print(mylist[3:5])

result:
[4,5]

List Manipulation

  • Add elements to the list.
    list + new element
  • Remove element from the list.
    del(list[i])

Example

x = [a, b, c]  
# address allocating  
y = x  
y[1] = z 

print(x)

result:
[a,b,c]
x = [a, b, c]
y = list(x)
y = x[:]
y[1] = z

print(x)

result:
[z,b,c]

Popular List Methods

Methods Description
len(list) to know the length of the list
list.append(el) to append the element to the list
list.pop(index) to pop out the element from the list
list.sort() to sort the elements of the list
list.reverse() to reverse the elements of the list
list.max() to get the maximum value of the list
list.min() to get the minimum value of the list