How do you Update a List in Python using a For Loop With Examples?

"How do you update a list in Python using a for loop?"

To update a list in Python using a for loop, you can iterate over the list's indices and modify each element in place.

You can use a for loop in Python to update various tasks, such as multiplying numbers, changing strings to uppercase, or applying your custom functions to each item in the list.

4 Examples To Update a List in Python Using a For Loop

Example 1) Using a for loop to update each element in the lists by reversing each sublist:

item1 = [1, 2, 3]
item2 = [4, 5, 6]
item3 = [7, 8, 9]

# Create a list of these items
my_list = [item1, item2, item3]

# Update each sublist by reversing it
for i in range(len(my_list)):
    my_list[i] = my_list[i][::-1]

print(my_list)

• my_list[i][::-1] reverses the sublist at index i.
• The loop iterates over each sublist in my_list and updates it with the reversed version.

Output:

Example 2) Using a for loop to update each element in the list by Incrementing each element by 1:

numbers = [1, 2, 3, 4, 5]

# Update each element by incrementing it by 1
for i in range(len(numbers)):
    numbers[i] += 1

print(numbers)

• range(len(numbers)) generates indices from 0 to len(numbers) - 1.
• numbers[i] += 1 updates each element at index i by adding 1.

Output:

Example 3) Using a for loop to update each element in the list by Converting each string in a list to uppercase:

words = ["apple", "banana", "cherry"]

# Update each element by converting it to uppercase
for i in range(len(words)):
    words[i] = words[i].upper()

print(words)

• words[i] = words[i].upper() updates each string in the list to its uppercase form.

Output:

Example 4) Using a for loop to update each element in the list by Multiplying each element by 2:

numbers = [1, 2, 3, 4, 5]

# Update each element by multiplying it by 2
for i in range(len(numbers)):
    numbers[i] *= 2

print(numbers)

• numbers[i] *= 2 update each element by multiplying it by 2.

Output:

Conclusion

In each example above, the for loop iterates over the list and updates its elements in place.

To update a list in Python with a for loop allows you to perform various operations like:

• arithmetic updates,
• string transformations,
• or applying custom functions to each element in the list.

Keep experimenting with different operations, and you'll see how helpful Python's for loop can be in your daily coding projects.

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