Python For Loop with If Statement

What is the need for an if statement inside for loop in Python and how to use it? We can iterate blocks of code using for loop and using an if statement along with it we can check for a specific condition and perform until the condition is False. For loop iterates over a sequence(such as a list, or tuple) and execute a specific action for each item in the sequence. In this article, I will explain the concept of an if statement within for loop with examples.

Below are some use cases of using if Statement with for Loop:

• if statement is used to check the condition of the iteration item.
• break statement is used mostly with if statement to break the loop.
• continue statement is used to skip the current iteration and go to the next one.

1. Quick Examples of For Loop with If Statement

Following are the quick examples of using For Loop with If statement

# Below are the quick examples

# Example 1: Iterate list using for loop with if
courses = ["c", "c++", "python", "java", "pandas"]
courses1 = ["java","python","pandas","sparks"]
for i in courses:
       if i in courses1:

# Example 2: Iterate given lists using for loop with if else statement
courses = ["c", "c++", "python", "java", "pandas"]
courses1 = ["java","python","pandas","sparks"]
for i in courses:
       if i in courses1:
           print(i)
       else:
           print(i)

# Example 3: Skip the loop using if and continue statement
courses=["java","python","pandas","sparks"]
for x in courses:
    if x == 'pandas':
        continue
    print(x)

# Example 4: Exit the loop using if and break statement
courses=["java","python","pandas","sparks"]
for x in courses:
    print(x)
    if x == 'pandas':
        break

# Example 5: Using break statement inside the nested loop with if 
courses1=["java","python"]
courses2=["pandas","java","python"]
for x in courses1:
     for y in courses2:
         if x==y:
             break
         print(x ,y) 

2. Python For Loop with If Statement

Using for loop with an if statement in Python, we can iterate over a sequence and perform different tasks for each item in a sequence until the condition falls a False. Let’s take two sets of lists and perform them using for loop with an if statement,

# Iterate given lists using for loop with if
courses = ["c", "c++", "python", "java", "pandas"]
courses1 = ["java","python","pandas","sparks"]
for i in courses:
       if i in courses1:
           print(i)

Yields below output.

From the above, using for loop we have iterated each item in a given list named courses. For every iteration, it will check if the item of courses presents in another list named courses1. If the item presents both two lists then will print the item as a output.

3. For Loop with If Statement and Else statement

Let’s take another example using for loop with if statement and else statement.

Here, For every iteration, it will check if the item of i==java then the loop will be terminated and else block won’t execute.

If the i!=java then the if condition will not be executed and our program will not reach the break statement to terminate the loop. Only then the else block will execute.

# Iterate given lists using for loop with if else statement
# Iterate given lists using for loop with if else statement
courses = ["c", "c++", "python", "java", "pandas"]
for i in courses:
       if i =="java":
           print("Java is found")
           break
else:
   print("Java is not found")           


Yields below output.

4. Using For Loop with If Statement and Continue

Below are some more examples we are going to see on a for loop with a break, continue, and if statements.

Using the if statement along with the continue statement we can skip the current iteration of the loop within a specific condition and continue to the next iteration of the loop.

# Skip the loop using if and continue statement
courses=["java","python","pandas","sparks"]
for x in courses:
    if x == 'pandas':
        continue
    print(x)
 

Yields below output.

# Output:
java
python
sparks

Here, I have taken courses as a list, which is iterated using for loop with the continue statement. Here as you can see continue statement is used within the if condition. If the loop reaches the 'pandas' the condition in the if the statement becomes True, so the continue statement will execute and skips the current iteration(pandas) and go for the next iteration.

Note: continue statement doesn’t exit the for/while loop.

5. Using For Loop with If Statement and Break

Sometimes you would like to exit from the python for/while loop when you meet certain conditions, using if and break statement you can exit the loop when the condition meets. The example is given below.

# Exit the loop using if and break statement
courses=["java","python","pandas","sparks"]
for x in courses:
    print(x)
    if x == 'pandas':
        break
 

From the above example, I have taken the courses variable as a list that is iterated using for loop. We have applied a break statement based on x == 'pandas' condition. If the iteration reaches the pandas value, the for loop will exit using a break statement.

The above example exits loop when x value equals to pandas.

# Output
java
python
pandas

6. Nested for Loop with If Statement

If a loop presents inside the body of another loop is called a nested loop. The inner loop will be executed n number of times for each iteration of the outer loop within a specific condition using if statement. The example is given below.

If the break statement is inside a nested loop, the break statement will end the innermost loop and the outer loop continue executing. Let’s take an example for a better understanding.

# Using break statement inside the nested loop with if 
courses1=["java","python"]
courses2=["pandas","java","python"]
for x in courses1:
     for y in courses2:
         if x==y:
             break
         print(x ,y) 

In the above example, the inner loop will be executed three times(‘pandas’, ‘java’, ‘python’) for each iteration of the outer loop.

Possibilities of the outer loop for the first iteration:

• java, pandas
• java, java in this case, the condition satisfies so the innermost loop ends. Then the control goes to the outer loop.

Possibilities of the outer loop for the second iteration :

• python, pandas
• python, java
• python, python in this case, the condition satisfies so the innermost loop ends.

Yields below output.

# Output
java pandas
python pandas
python java

7. Conclusion

In this article, I have explained the concept of an if statement within a for loop in Python and used these combinations while iterating how we can control and perform the given sequence with examples. Also learned the significance of the if statement to break & continue the looping.

Related Articles

• For Loop Break Statement in Python
• Iterate Over an Array in Python
• For Loop Continue And Break in Python
• How to Perform Decrement for Loop in Python
• How to Increment for Loop in Python
• For Loop Enumerate in Python
• Get Counter Values in a for Loop in Python?
• Access Index in for Loop in Python

References

• https://wiki.python.org/moin/ForLoop