ValueError: Too Many Values to Unpack

ValueError: Too Many Values to Unpack

  1. What Is ValueError in Python
  2. Fix the ValueError: too many values to unpack in Python
  3. Handle Exception ValueError: too many values to unpack With Try-Catch in Python

The ValueError: too many values to unpack sometimes occurs when the variables on the left of the assignment operator = are not equal to the values on the right side of the assignment operator =.

It commonly happens when you try to take more than one input from the user in a single input statement or assign unequal variables to some values.

What Is ValueError in Python

A ValueError is a common exception in Python that occurs when your number of values does not meet the number of variables either taking input, direct assignment or through an array. To understand the ValueError, let’s take an example.

Code example:

# take two string values as input separated by a comma
x,y = input("Enter x and y: ").split(",")

Output:

Eneter x and y: 3,2,1
ValueError: too many values to unpack (expected 2)

As you can see in the above code, we are taking two inputs, x and y; the input statement expects two values separated by the comma ,.

But in this case, we have provided three values as input to demonstrate the topic, which has thrown the ValueError: too many values to unpack.

Another case of the ValueError: too many values to unpack could be directly assigning values to variables. Let’s understand it through an example.

a,b = 2, 3, 5 #ValueError: too many values to unpack (expected 2)
a,b,c = 2, 3  #ValueError: not enough values to unpack (expected 3, got 2)
a,b = [3,2,1] #ValueError: too many values to unpack (expected 2)

The above are a few other cases that throw the ValueError.

Fix the ValueError: too many values to unpack in Python

To avoid the ValueError, you should provide the exact number of values as expected by either the input statement, a list or an array. The best practices are to use try-catch blocks and display messages to the users to guide them.

Let’s understand how we can fix the ValueError: too many values to unpack.

# User message --> Enter the two numbers to add  ::
a,b = input("Enter two numbers to add  ::  ").split(",")

# type casting a and b
a = int(a)
b = int(b)

print("The sum of the two numbers is     :: ",a+b)

Output:

Enter two numbers to add  ::  22,23
The sum of the two numbers is     ::  45

Handle Exception ValueError: too many values to unpack With Try-Catch in Python

Almost every other programming language has the try-catch mechanism for exception handling. Exception handling is a proactive mechanism that controls the errors or exceptions before crashing the program and helps display the nature and cause of the error.

Also, you can display your messages to interpret the exceptions.

Let’s understand it through an example.

try:
    # User message --> Enter the two numbers to add  ::
    x,y = input("Enter  two numbers to add  ::  ").split(",")

    # type casting x and y
    x = int(x)
    y = int(y)
    print("The sum of the two numbers is      :: ",x+y)

except ValueError as v:
    print("Oops! Looks like you have enter an invalid number of input" +
                "\nPlease enter two numbers to add")
    print("ValueError:",v)

print("\nWow! The program is not crashed.")

Output:

Enter  two numbers to add  ::  1,2,3
Oops! Looks like you have enter an invalid number of input
Please enter two numbers to add
ValueError: too many values to unpack (expected 2)

Wow! The program is not crashed.

As you can see, the above program is failed, and it causes the ValueError, but note that the program has not yet crashed.

You can see the code in the try block has caused the ValueError exception, and instead of crashing it at the line, the try block has passed the error to the except block, which interprets the exception and displays a customized message to the user. The customized message helps us interpret the error easily.

Zeeshan Afridi avatar Zeeshan Afridi avatar

Zeeshan is a detail oriented software engineer that helps companies and individuals make their lives and easier with software solutions.

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