How to use the for loop in Python
In Python, the for loop is used to iterate over a sequence (such as a list, tuple, string, or dictionary) or any iterable object. The basic syntax of the for loop is:
Python For Loop Syntax
for var in iterable:
# statements
Note: In Python, for loops only implement the collection-based iteration.
Here we will see Python for loop examples with different types of iterables:
Python For Loop with String
This code uses a for loop to iterate over a string and print each character on a new line. The loop assigns each character to the variable i and continues until all characters in the string have been processed.
# Iterating over a String
print("String Iteration")
s = "Geeks"
for i in s:
print(i)
Output:
String Iteration
G
e
e
k
s
Python for loop with Range
This code uses a Python for loop with index in conjunction with the range() function to generate a sequence of numbers starting from 0, up to (but not including) 10, and with a step size of 2. For each number in the sequence, the loop prints its value using the print() function. The output will show the numbers 0, 2, 4, 6, and 8.
for i in range(0, 10, 2):
print(i)
Output :
0
2
4
6
8
Python for loop Enumerate
In Python, the enumerate() function is used with the for loop to iterate over an iterable while also keeping track of the index of each item.
l1 = ["eat", "sleep", "repeat"]
for count, ele in enumerate(l1):
print (count, ele)
Output
0 eat
1 sleep
2 repeat
Nested For Loops in Python
This code uses nested for loops to iterate over two ranges of numbers (1 to 3 inclusive) and prints the value of i and j for each combination of the two loops. The inner loop is executed for each value of i in the outer loop. The output of this code will print the numbers from 1 to 3 three times, as each value of i is combined with each value of j.
for i in range(1, 4):
for j in range(1, 4):
print(i, j)
Output :
1 1
1 2
1 3
2 1
2 2
2 3
3 1
3 2
3 3
Python For Loop Over List
This code uses a for loop to iterate over a list of strings, printing each item in the list on a new line. The loop assigns each item to the variable I and continues until all items in the list have been processed.
# Python program to illustrate
# Iterating over a list
l = ["geeks", "for", "geeks"]
for i in l:
print(i)
Output :
geeks
for
geeks
Python for loop in One Line
Numbers =[x for x in range(11)]
print(Numbers)
Output
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
Python For Loop with Dictionary
This code uses a for loop to iterate over a dictionary and print each key-value pair on a new line. The loop assigns each key to the variable i and uses string formatting to print the key and its corresponding value.
# Iterating over dictionary
print("Dictionary Iteration")
d = dict()
d['xyz'] = 123
d['abc'] = 345
for i in d:
print("% s % d" % (i, d[i]))
Output:
Dictionary Iteration
xyz 123
abc 345
Python For Loop with Tuple
This code iterates over a tuple of tuples using a for loop with tuple unpacking. In each iteration, the values from the inner tuple are assigned to variables a and b, respectively, and then printed to the console using the print() function. The output will show each pair of values from the inner tuples.
t = ((1, 2), (3, 4), (5, 6))
for a, b in t:
print(a, b)
Output :
1 2
3 4
5 6
Python For Loop with Zip()
This code uses the zip() function to iterate over two lists (fruits and colors) in parallel. The for loop assigns the corresponding elements of both lists to the variables fruit and color in each iteration. Inside the loop, the print() function is used to display the message “is” between the fruit and color values. The output will display each fruit from the list of fruits along with its corresponding color from the colours list.
fruits = ["apple", "banana", "cherry"]
colors = ["red", "yellow", "green"]
for fruit, color in zip(fruits, colors):
print(fruit, "is", color)
Output :
apple is red
banana is yellow
cherry is green
For Loops in Python
The For Loops in Python are a special type of loop statement that is used for sequential traversal. Python For loop is used for iterating over an iterable like a String, Tuple, List, Set, or Dictionary.
In Python, there is no C style for loop, i.e., for (i=0; I <n; i++). The For Loops in Python is similar to each loop in other languages, used for sequential traversals.
Table of Content
- Flowchart of Python For Loop
- How to use the for loop in Python
- Python For Loop Syntax
- Python For Loop with String
- Python For Loop with Integer
- Python for loop Enumerate
- Nested For Loops in Python
- Python For Loop with List
- Python For Loop with Dictionary
- Python For Loop with Tuple
- Python For Loop with Zip()
- Control Statements that can be used with the For Loops in Python
- Python For Loop Exercise Questions