Unhashable type list

The Python TypeError: unhashable type: 'list' usually means that a list is being used as a hash argument.

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Unhashable type list

It will allow Python to create unique hash values for the keys. This error shows that the fruits key [2,4,6 ] is a list and not a hashable type in Python. Dictionary keys must be immutable types, and the list is a mutable type. The easiest way to resolve this error is to convert the list into a tuple. Though tuples may seem similar to lists, they are often used for different purposes. Tuples are immutable and contain a heterogeneous sequence of elements that are accessed via unpacking or indexing. On the other hand, lists are mutable, and the elements are homogeneous, and the elements are accessed by iterating over the list. Since we know that lists are mutable, instead of adding lists as a key in the dictionary, you could store it as a value. The example below demonstrates how to add a list into a dictionary as a value. Are you sure you want to hide this comment?

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The TypeError: unhashable type: 'list' usually occurs when you try to use a list object as a set element or dictionary key and Python internally passes the unhashable list into the hash function. But as lists are mutable objects, they do not have a fixed hash value. The easiest way to fix this error is to use a hashable tuple instead of a non-hashable list as a dictionary key or set element. This is not a trivial problem because Python lists are mutable and, therefore, not hashable. In fact, the error can be reproduced most easily when calling hash lst on a list object lst.

Dictionary in Python is an unordered collection to store data values in key:value pairs. Key acts as an identifier to access and retrieve the value in the dictionary. It will allow Python to create unique hash values for the keys. This error shows that the fruits key [2,4,6 ] is a list and not a hashable type in Python. Dictionary keys must be immutable types, and the list is a mutable type. The easiest way to resolve this error is to convert the list into a tuple. Though tuples may seem similar to lists, they are often used for different purposes. Tuples are immutable and contain a heterogeneous sequence of elements that are accessed via unpacking or indexing. On the other hand, lists are mutable, and the elements are homogeneous, and the elements are accessed by iterating over the list. Since we know that lists are mutable, instead of adding lists as a key in the dictionary, you could store it as a value.

Unhashable type list

In python, there are many types of errors as once the code has many types of problems in which this error will come. Errors will always define which type of problem has occurred in the solution. Now there is a problem to know which object is hashable and which object is not. Now we are trying to find hash value for the set and when are printing the value the error occurs as the hash value is not coming so we cannot use it as a key in the dictionary in the set. So to avoid this error by removing the mutable object or replacing it with some immutable object and your code will run properly. The set or dictionary will use a hash statement for the storage of elements. A particular hashcode is being given to the set. The list is mutable so we can do implementation on the list at any time in the code and it will give unhashable value. Suppose we are taking the employees and finding their marks of training to decide the promotion and we are taking the information in the dictionary.

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Have a question about this project? Can it be some cache problems? The documentation will be improved to state this clearly. To resolve this issue, you would need to ensure that you're not using a list in a context where a hashable type is required. The example below demonstrates how to add a list into a dictionary as a value. In the example above, the tuple function is used to convert the list to a tuple. On the other hand, lists are mutable, and the elements are homogeneous, and the elements are accessed by iterating over the list. I am Dosu , a bot designed to assist you with your technical issues, answer your questions, and guide you towards becoming a contributor. What is map, filter and reduce in python? Since we know that lists are mutable, instead of adding lists as a key in the dictionary, you could store it as a value.

As you already know list is a mutable Python object. For hashing an object it must be immutable like tuple etc.

Find a top-rated training program. To resolve this, consider using tuples, which are immutable and can serve as hashable alternatives in such contexts. To fix the TypeError: unhashable type: 'list' when trying to use a list as a set element is to use a hashable tuple instead of a non-hashable list. The standard way to solve this issue is to cast a list to a tuple, which is a hashable data type. To fix this error, you can convert the 'list' into a hashable object like tuple then use it as a key for 'set' as shown below:. Immutable objects such as tuples are hashable since they have a single unique value that never changes. This error occurs when you try to use a list as key in the dictionary or set. While tuples might appear similar to lists, they frequently serve distinct roles and have different applications. We believe that user-generated reviews offer valuable insights and diverse perspectives, helping our users make informed decisions about their educational and career journeys. However, without the exact line of code or stack trace where the error is occurring, it's difficult to pinpoint the exact cause. The example below demonstrates how to add a list into a dictionary as a value. It will allow Python to create unique hash values for the keys.