Python will automatically assign the values in the iterable to the variables so that the asterisked’ variable captures all remaining elements. ⚡ Note: This only works in Python 3 but not in Python 2. Here’s an example where we capture two elements 2 and 3 in one variable b using the asterisk operator as a prefix in *b: a, *b, c = This way, you can overcome the ValueError: too many values to unpack when there are more values in the iterable than there are variables to capture them. You can use the asterisk operator * on the left-hand side of the equation to unpack multiple elements into a single variable. Per convention, it is used if you don’t actually care about the value stored in it but just use it to capture all values from an iterable in a syntactically correct way. The underscore _ in Python behaves like a normal variable name. The simple heuristic to understand what is going on here is: parallel structures! Python Unpacking Underscore This can be done by setting up a parallel structure on the left and right sides of the equation using parentheses (.) or square brackets. The simple case is where one variable (in our example c) captures the whole inner list (in our example ): lst = ]īut how can you assign the elements of the inner list to variables as well? You can also unpack a nested iterable (e.g., list of lists, or tuple of tuples). Each variable captures one character from the string, in order, after the unpacking operation. In the following example, you unpack the seven characters in the string 'finxter' into variables a, b, c, d, e, f, and g. String unpacking is the process of assigning k characters of a string to k different variables in a single line of code. Note that the parentheses of tuples are optional, so you can omit them to obtain the same behavior with even fewer syntax overhead as shown in the following example. Each variable captures one tuple element after the unpacking operation. In the following example, you unpack the three elements in the tuple (1, 2, 3) into variables a, b, and c. Tuple unpacking is the process of assigning k elements of a tuple to k different variables in a single line of code. To resolve the ValueError: not enough values to unpack (expected x, got y), make sure that the number of elements on the right and left-hand sides of the unpacking operation is the same. ValueError: not enough values to unpack (expected 4, got 3) This can be seen in the following code snippet: a, b, c, d = If the iterable has too few values to unpack - i.e., the number of elements in the iterable is larger than the variables to assign them to - Python will raise a ValueError: not enough values to unpack (expected x, got y) whereas x is the number of variables on the left-hand side of the assignment operation and y is the number of elements in the iterable. Here’s the same example resolved using the underscore name: a, b, _, c = Īlternatively, you can also use the asterisk operator on the left-hand side as will be explained at the end of this article-so keep reading! ? ValueError: not enough values to unpack (expected x, got y) Per convention, if you don’t need to store a certain list element in a variable, you can use the “throw-away” underscore variable name _. To resolve the ValueError: too many values to unpack (expected k), make sure that the number of elements on the right and left-hand sides of the unpacking operation is the same. ValueError: too many values to unpack (expected 3) This can be seen in the following code snippet: a, b, c = įile "C:\Users\xcent\Desktop\code.py", line 1, in If the list has too many values to unpack - i.e., the number of elements in the list is larger than the variables to assign them to - Python will raise a ValueError: too many values to unpack (expected k) whereas k is the number of variables on the left-hand side of the assignment operation. # 3 ValueError: too many values to unpack (expected k) Each variable captures one list element after the unpacking operation. In the following example, you unpack the three elements in the list into variables a, b, and c. List unpacking is the process of assigning k elements of a list to k different variables in a single line of code. For it to work, you need to have enough variables to capture the number of elements in the iterable. ? Iterable unpacking or sequence unpacking is the process of assigning the elements of an iterable (e.g., tuple, list, string) to multiple variables. Python allows you to assign iterables such as lists and tuples and assign them to multiple variables. ValueError: not enough values to unpack (expected x, got y).ValueError: too many values to unpack (expected k).In this article, you’ll learn about the following topics:
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