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Python

Posted by Lior Dolinski
Lior Dolinski
3,905 Points

ValueError : not enough values to unpack. why?

i tried building a simple function which solves a simple equation. (such as x+4=9)

 def solve_eq(equation):
    x, add, num1, equal, num2 = equation.split()

    num1, num2  = int(num1), int(num2)

    return "x = " + str(num2 - num1)

print(solve_eq("x+4=9"))

but all i get is: ValueError: not enough values to unpack (expected 5, got 1)

i know its cause of the split.() but it should work, no? you can assign multiple variables to that split (assuming you know that exactly 5 are going to come out of split)

1 Answer

Benjamin Lange
Benjamin Lange
16,178 Points
Benjamin Lange
Benjamin Lange
16,178 Points

By default, the split() function will split on white space. Since there are no spaces separating each part of the equation, that function call will not work. As far as I know, there isn't a way to split each individual character if there is no character separating the values using the split() function.

Instead, convert the equation into a list:

x, add, num1, equal, num2 = list(equation)

That will assign each variable one of the characters from the equation string that is passed in. Note that this will not work with numbers that contain more than one digits.

Iain Simmons
Iain Simmons
Treehouse Moderator 32,305 Points

Or, just:

x, add, num1, equal, num2 = equation
Benjamin Lange
Benjamin Lange
16,178 Points

Oh, awesome! I didn't know you could do that.

Iain Simmons
Iain Simmons
Treehouse Moderator 32,305 Points

Yeah, neither did I, but I suspected it would work, because Python is awesome! :)

Benjamin Lange
Benjamin Lange
16,178 Points

It really is. I came from a C# world and Python makes a lot of things so much easier to do. :)