python-learning/19_add_remove_update_lists.py at main · shaikmunna-data/python-learning · GitHub

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#======================================================================================
#                               Add Remove & Update Lists
#--------------------------------------------------------------------------------------
# In python, lists are mutable, so you can easily
# Add, Remove, and Update Items
#======================================================================================

#--------------------------------------------------------------------------------------
# Add items to list
#--------------------------------------------------------------------------------------
# .append(value)              --Add one item at the end of list
# .insert(index, value)       --Add item at specific position
#--------------------------------------------------------------------------------------

letters = ['a', 'b', 'c']
# Add 'x' to the end of the list
letters.append('x')
print(letters)
# Add 'y' at the start of the list
letters.insert(0, 'y')
print(letters)
# Add 'z' between 'b' and 'c'
letters.insert(3, 'z')
print(letters)

#--------------------------------------------------------------------------------------
# Add items to nested list
#--------------------------------------------------------------------------------------
matrix = [
    ['a', 'b', 'c'],    # Row 0
    ['d', 'e', 'f'],    # Row 1
    ['g', 'h', 'i']     # Row 2
]

# Add new row to the end of matrix
matrix.append(['x', 'y', 'z'])
print(matrix)
# Add 'x' at the end of the second roe
matrix[1].append('x')
print(matrix)
# Add new roe at the start of matrix
matrix.insert(0, ['p', 'q', 'r'])
print(matrix)
# Add 'z' at the start of the first row
matrix[0].insert(0, 'z')
print(matrix)

#--------------------------------------------------------------------------------------
# Remove items from list
#--------------------------------------------------------------------------------------
# .clear()          --Remove everything from list
# .remove(value)    --Remove by value(Removes only the first match) & (error occurs if item doesn't exist)
# .pop(index)       --Remove by index
# .pop()            --pop() without index removes last item
#--------------------------------------------------------------------------------------
letters = ['a', 'b', 'c', 'd', 'e']
print(letters)
# Remove 'a' from the list
letters.remove('a') # removes only the first match
print(letters)
# Remove the first item
letters.pop(0)
print(letters)
# Remove the last item
letters.pop() # pop() without index no removes last item
print(letters)
# Remove everything from list
letters.clear() # Removes everything from list
print(letters)

#--------------------------------------------------------------------------------------
# Remove items from nested list
#--------------------------------------------------------------------------------------
matrix = [
    ['a', 'b', 'c'],    # Row 0
    ['d', 'e', 'f'],    # Row 1
    ['g', 'h', 'i']     # Row 2
]

print(matrix)
matrix.remove(['a', 'b', 'c'])
print(matrix)
# Remove last row
matrix.pop()
print(matrix,'\n')

matrix = [
    ['a', 'b', 'c'],    # Row 0
    ['d', 'e', 'f'],    # Row 1
    ['g', 'h', 'i']     # Row 2
]

# Remove 'e' from matrix
matrix[1].remove('e')
print(matrix)
# Remove 'g' from matrix
matrix[-1].pop(0)
print(matrix)
# Remove last item of the first list
matrix[0].pop()
print(matrix)
print()
#--------------------------------------------------------------------------------------
# Update items in list
#--------------------------------------------------------------------------------------
# lst[index] = value
#--------------------------------------------------------------------------------------
letters = ['a', 'b', 'c']
# Update the first item to 'x'
letters[0] = 'x'
print(letters)
# UPdate the  second item to 'z
letters[1] = 'z'
print(letters)

#--------------------------------------------------------------------------------------
# Update items in nested list
#--------------------------------------------------------------------------------------

matrix = [
    ['a', 'b', 'c'],    # Row 0
    ['d', 'e', 'f'],    # Row 1
    ['g', 'h', 'i']     # Row 2
]

print(matrix)
# Update the content of the last list
matrix[-1] = ['x', 'y', 'z']
print(matrix)
# Update the first item of the first row
matrix[0][0] = '-'
print(matrix)
# Update the second item of the second row
matrix[1][1] = '-'
print(matrix)
# Update the third item of the third row
matrix[-1][-1] = '-'
print(matrix)