list data type does not have any difference function, You may want to create output1 and output2 as set, Example -. 이 오류는 목록과 같은 해시할 수 없는 객체를 Python 사전에 키로 전달하거나 함수의 해시 값을 찾을 때 발생합니다. If you want to use lru_cache the arguments must be, for example, tuple s instead of list s. 使用元组替代列表. I want to update a piechart with dash: @app. Can you tell more about or add a Tag for your particular programming context, like it being python or javascript – Stefan Wuebbe. Not to mention that in some cases the underlying estimators would have to be wrapped to undo the conversion (or some other mehtod such as. So, you can't put mutable objects in a dict. They are unhashable only if they contain at least one mutable item. g. answered May 2, 2017 at 20:01. 03:07 So now that you know what immutable and hashable mean, let’s look at how we can define sets. TypeError: unhashable type: 'list' or. Station , put instead df. If the l_user_type_data is a variable contains a string, you should do: temp_dict = dict () temp_dict [l_user_type_data] = user_type_data result = json. uniform (size= (10,2)). tuple (mylist) should be good enough to convert the list to a tuple. TypeError: unhashable type: 'list' in Django/djangorestframework. Deep typing. As an example of an other object type which is mutable and not hashable by design, consider list and this example: >>> L = [1, 2, 3] >>> set ( [L]) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: unhashable type: 'list. This error occurs when trying to hash a list, which is an unhashable object. lst = [ ['Descendant Without A Conscience', 'good', 'happy'], ['Wolf Of The Solstice. 4. You provide an unhashable key (args,kwargs) since kwargs is a dict which is unhashable. 8. 7; pandas; pandas-groupby; Share. 2 Answers. Try. drop_duplicates () And make sure to use it on specific columns which need it, and not all. For list of list, what you get is a list. If the dictionary contains sub-dictionaries, we might have to take a recursive approach to make it hashable. sum () If no NaN s values is possible use IanS solution: l = (df ['files']. Summary A DataFrame which contains a list is unhashable and therefore breaks st. frozen=True prevents you from assigning new values to the attributes; it does not. replace('. The way you tried to index into the Dataframe by passing a tuple of single-element lists will interpret each of those single element lists as indicesascending bool or list of bool, default True. That’s like 99. You may have observed this, in case you ever tried to use lists as keys in a dictionary. Highest score (default) USE sqlalchemy 1. Under Python ≥ 3. Teams. pie. スライスを. Simple approach: DY = {key: value for keys, value in zip (YiW, YiV) for key in keys} Note that this will drop data if any key appears more than once (so if YiW contains both ["africa", "trip"] and. Reload to refresh your session. gather accepts coroutine (or other awaitable) arguments and returns a tuple of their results in the same order. zip returns a list of tuples, not a tuple. asked Jul 23, 2015 at 13:46. 6 and previous dictionaries are unordered. When I try running the program I get a Type error: unhashable type: 'list'. Although you didn't specify exactly what data is, data['tweet_split'] is likely returning a list of lists, and FreqDist is a probably a dictionary-like object. append (data) Hi all, Working on the assignment “Cleaning US Census Data” and I have to. The clever idea to use foo. items (): keys. I guess they ran out of (types of) braces. Because python lists are mutable (ie they can change content), they can't have a fixed hash value associated with them. Sometimes mutable types like lists (or Series in this case) can sneak into your collection of immutable objects. append (channel) top = flask. 4. When I try to call the function on a list, I get this error: 'TypeError: unhashable type: 'list''. ', '') # split words in data (splitted by whitespace) and save in. 왜냐하면, 사실상 a[result]에서 요청하는 값이 a[[1]] 이런 모양이기 때문이다. It means at least one (if not more) of the values in that column is a list not a string. I tried the other answers but they didn't solve what I needed (large dataframe with multiple list columns). AMC. ServerProxy. Random number generator, unhashable type 'list'. Besides, a tuple is only hashable if each of its elements are hashable. TypeError: unhashable type: 'list' in python. The problem does not occur in a new Python 3. userThrow = raw_input ("Enter Rock [r] Paper [p] or Scissors [s]") # raw_input () returns a string, and. ndarray error, you can modify the code by converting the NumPy ndarray to a hashable type, like a tuple. TypeError: unhashable type: 'dict' The problem is that a list/dict can't be used as the key in a dict, since dict keys need to be immutable and unique. Generally, the cause of the unhashable “TypeError” in Python is when your code is directly or indirectly trying to hash an unhashable data type like lists and Pandas “Series” objects. curdir foodName = re. And, the model contains three entries for the. For "TypeError: unhashable type: 'list'", it is because you are actually passing the list in your dict when you seemingly intend to pass the key then access that list: animals_mix (dic ['reptiles'], tmp). split () ld (tuple (s), tuple (t)) Otherwise, you may avoid using lru_cached functions by using loops with extra space, where you memoize calculations. Method 5: Convert Inner Lists to Strings. Hot Network Questions Print the answer before a given answer How to describe the Sun's location to an alien from our Galaxy?. 6. channels = a. You switched accounts on another tab or window. Sep 1, 2022 at 15:45. 2. 1 Answer. Why Python TypeError: unhashable type: 'list' Hot Network Questions Is a buyout of this kind of an inheritance even an option? Why do most French cities that have more than one word contain dashes in them?. The dict keys need to be hashable (which usually means that keys need to be immutable) So, if there is any place where you are using lists, you can convert it into a tuple before adding to a dict. If a column is not contained in the DataFrame, an exception will be raised. Generic type-checking. split () t = "how Halo how you are the ?". get (myFoodKey) This results in: TypeError: unhashable type: 'list'. Jun 25, 2021 at 22:27. This was a deliberate design decision, and can best be explained by first understanding how Python dictionaries work. If all you need is any element from the dictionary then you could do:You can't groupby by any column that contains an unhashable type, a list is one of those, for instance if you did df. 1 # Unhashable type (dict) 2 my_dict = {'Name': 'Jim', 'Age': 26} ----> 3 print (hash (my_dict)) TypeError: unhashable type: 'dict'. Lê Hồng Nhật. The hash value of an object is meant to semi-uniquely represent that object. A python List transactions is mutable, therefore you cant use it as a key return_dict[transactions]. 1 1 1 silver badge. TypeError: unhashable type: 'list'. temp = nr. Otherwise, if you want that each element of the set is a list, you should use a list for visited instead of a set and implement a solution to avoid duplicates. unhashable type: 'dict' How should I solve this issue? Thanks in advance. Q&A for work. Follow edited Jul 23, 2015 at 15:27. ndarray' errors respectively. S: The code has a whole lot of bugs so don't mind that. – A list is a mutable type, and cannot be used as a key in a dictionary (it could change in-place making the key no longer locatable in the internal hash table of the dictionary). 2. Then in. 7; dictionary; Share. TypeError: unhashable type: 'set' sage: s = X. An Unhashable Type List is a list of objects of certain types that can’t be used as a key in a Python dictionary. In your code you are passing kmersdatapos to Word2Vec, which is list of list of list of strings. From what I can understand, you got lists in your data frame and python or Pandas can not hash lists. You signed out in another tab or window. TypeError: unhashable type: 'list' for comparing pandas columns. A set contains unique elements. unhashable: list, dict, set; となっていますが、ここで hashable の方に入っているものは、ハッシュ値が生存期間中変わらないことが保証されています。では、ユーザ定義オブジェクトの場合はどうでしょうか？ ユーザ定義オブジェクトの場合 unhashable な. apply (lambda x: tuple (*x), axis=1). 5. df_dict[key] = ( df # Make everything lower case . I am currently working on the lemmantization of a word from a csv file, where afterwards I passed all words in lowercase letters, removed all punctuation and split the column. Summary. TypeError: unhashable type: 'list' df_data = df[columns] 0. A tuple would be hashable, so you could try the following updated code to fix. If we convert it into a string as 'd' then this will work fine. set cheat sheet type set use Used for storing. e. setparams function, you put this list into self. 1. piRSquared. falsetru. But it throws a TypeError:def my_serialize(key_nums: list): key_nums = sorted(key_nums) base = max(key_nums) sum_ = 0 for power, num in enumerate(key_nums): sum_ += base**power * num return sum_ which should give you a unique (incredibly large!) integer to store that will be smaller in memory than the tuple. You'd need to make the dict comprehension use nested loops to pull this off, since each value in YiW is a list of keys to make, not a single key. ndarray 作为键，我们将遇到 TypeError: unhashable type: 'list' 和 TypeError: unhashable type: 'numpy. Examples of unhashable types include lists, sets, and dictionaries themselves. ndarray' Hot Network Questions Why space is [not] ignored in macro arguments? Is it possible to edit name in a paper at the stage of pre-proof correction after acceptance? Not sure if "combined 90 men’s years experience" is right usage as opposed to "combined 90 man years worth of. Generally, the cause of the unhashable “TypeError” in Python is when your code is directly or indirectly trying to hash an unhashable data type like lists and Pandas “Series”. What could be the reason and how to solve it. Reload to refresh your session. This will return the subset of rows where at least a single cell is a list, which should help you locate the problem. For example, an object of type tuple can be hashable or not. This won’t work because a list is an unhashable object. datablock = DataBlock (blocks = [text_block, MultiCategoryBlock], get_x=ColReader (twipper. So you can't use drop_duplicates because dicts are mutable and not hashable. In BasePlot. Python IO Unhashable list Regex. Learn more about TeamsTypeError: unhashable type: 'list' in 'analyze' method building target_dict["duplicates"] #106. dict, set ). The first1 Answer. The error TypeError: unhashable type: 'list’ explain itself what it means. 0. This will return the subset of rows where at least a single cell is a list, which should help you locate the problem. asked May 24, 2020 at 14:22. Share. def animals_mix (k, l): list1 = combine2 (FishList, dic [k]) in the first line of animals_mix () you are actually trying to do. apply (pandas. Don't understand what the problem is. You are using list as an key in the dictionary. apply (len) == 0). 89e-05 seconds. I'm creating my target dictionary exactly as I have been creating my "source" dictionary how is it possible this is not working ? I get . See the *args in the transpose docs. getCostOfActions(self. Since the tuples can be hashed, you can remove duplicates using set (using a set comprehension here, older python alternative would be set (tuple (d. I have listA=[[0,1,2]], and listB=[[0,1,2],[0,1,3],[0,2,3]], and want to obtain elements that are in listB but not in listA, i. 1 # retrieve the value for a particular key 2 value = d[key] Thus, Python mappings must be able to, given a particular key object, determine which (if any) value object is associated. tolist () array = [tuple (i) for i in temp] This should create the input in the required format. I want group by year and month, then calculate the means,why it has wrong? python; python-2. Subscribe Following. Python3 defaulted to using view objects for accessing dicts, if you change the underlying dictionary the view object reflects the change. df_list = [] for filename in files: data = pd. To allow unhashable keys in Counter, I made a Container class, which will try to get the object's default hash function, but if it fails, it will try its identity function. The best I can point you to is the archive link for that entire month of messages ; you can Ctrl-F for { to find the relevant ones (and a few false positives). eq(list). Q&A for work. 4. } and then immediately inside you have square brackets - [. In general, if you have some complex expression that causes an exception, the first thing you should do is try to figure out which part of the expression is causing the problem. How to fix 'TypeError: unhashable type: 'list' error? 0. TypeError: unhashable type: 'list' when using built-in set function. 32. Improve this question. Thanks, I have solved my code problem. 5. So when you do fd[i] += 1 you are indexing fd with a list, which with a dictionary or something that uses dictionaries in their implementation is not possible, because lists are not hashable. TypeError: unhashable type: <whatever> usually happens when you try to use something unhashable as a key in a hash indexed data structure (e. Tuples are sequences, just like lists. Since you set eq=True and left frozen at the default ( False ), your dataclass is unhashable. Do you want to pick values for id and phone from "id" : ["5630baac3f32df134c18b682","564b22373f32df05fc905564. 따라서 이를 해결하기 위해서는 a[1] 과 같이 접근해야하고, 그럼 int type으로 변환이 필요하다. keys()の戻り値は下記のようになるが、（多分）これが純粋なlistではない故に発生するエラーなのに、エラー内容がTypeError: unhashable type: 'list'というのは分かりづらい…。If an object has logical equality, updating that object would change its hash, violating rule 2. You have a Ratings column which is filled with dictionaries. The offending line is db[key] = [value] that throws a TypeError:unhashable type list, which means you passed a list type as key argument for the update_db function. -When I am doing same for another column for bigger dataset,it is self joining easily. If ngrams is a list of lists, as you've indicated in a comment to your question, then FreqDist () may be attempting to create a dictionary using the elements of ngrams as keys. Then print the most data that often appears (mode/modus). Ok, thanks for updating the question with the full code and traceback. Share FollowTypeError: unhashable type: 'set' When I print out the respective elements in the iteration, it shows that the result of the set comprehension contains not the expected scalars but lists: print {tup[1] for tup in list_of_tuples} set([100, 101, 102])The element of set need to be hashable, which means immutable, use tuple instead of list. 1. 2 Answers. Follow asked Dec 2, 2022 at 11:04. This fails because a list is unhashable. xlsm) file and copying some values from it to some other positions in the same file. 例如，如果我们尝试使用 list 或 numpy. e. To use a dict as a key you need to turn it into something that may be hashed first. Tuples are hashable. 5 hash (t2) # TypeError: unhashable type: 'list' สำหรับ User-defined Types เช่นการสร้างคลาสและออบเจ็กต์ขึ้นมาเอง โดยปกติจะถือว่าเป็น hashable object นั่นเพราะค่าปกติของ hash. You need to use a hashable collection instead, like a tuple. Modified 1 year, 1 month ago. Symmetric difference of two pandas dataframes. fromkeys instead:. Furthermore, unintended Series objects may be the cause. TypeError: unhashable type: 'list' for comparing pandas columns. Ask Question Asked 4 years, 2 months ago. Python dictionary : TypeError: unhashable type: 'list' 0. it likely means that either the way SQLAlchemyUserDatastore (db, User, Role) or the way create_user () is being used is wrong, as I'd assume this package wants to add Role objects to a collection (and a Role object would be hashable). I have added few lines on the original code to achieve this: channel = ['updates'] channel_list = reader. actually with just a few weeks of experience in python you get used to the fact that dicts are far widely used than sets and to the default behaviour of {} – Ishan SrivastavaTeams. List is not a hashable type in python. So you can. Unhashable objects will be treated as if they are hashable. You are returning a list to something that expects a hashable type, like an int, a string or a tuple of hashable types. ', '') data2 = data2. A user asks how to modify a list in a dictionary with a list as an key and get the desired output. assign (Bar=1) to obtain the Foo and Bar columns was taken. 7)1 Answer. Now there is a problem to know which object is hashable and which object is not. Diving into the details. Ludovica Ludovica. In the string data type, the values are characters. In this tutorial we are going solve unhashable type error. items (or friends) may not be in an order useful to you. Provide details and share your research! But avoid. I have a dataframe df which is as follows. The docs say:. str, bytes, frozenset, and tuple are immutable and therefore hashable. TypeError: unhashable type: 'list' Code : Why Python TypeError: unhashable type: 'list' Hot Network Questions Do creatures attempt a saving throw immediately when a Whirlwind is moved onto them on a turn subsequent to the initial casting? Python の TypeError: unhashable type: 'list' このエラーは、リストなどのハッシュ不可能なオブジェクトをキーとして Python 辞書に渡したり、関数のハッシュ値を検索したりするときに発生します。 Dictionaries は Python のデータ構造であり、キーと値のペアで機能します。 The hash() function is a built-in Python method utilized to generate a distinct numerical value. TypeError: "unhashable type: 'list'" python; Share. A way to fix this is by converting lists to tuples before passing them to a cached function: since tuples are immutable and hashable, they can be cached. You could use it in a following manner: df_exploded = df. The labels on the control types are also weirdly duplicated: It appears to be passing values like ["Lineart","Lineart"] instead of just "Lineart" to select_control_type. See also TypeError: unhashable type: 'list' when using built-in set function for more information on that. 当我们的数据取两列作为key时，它的key的类型就会变为列表。这时候如果要进行针对于可以的操作，就会出现上方所说的“TypeError: unhashable type: 'list'”，查看了一些其他资料后发现Python不支持dict的key为list或set或dict类型，因为list和dict类型是unhashable（不可哈希）的。TypeError: unhashable type: 'list' What am I doing wrong? python; pandas; dataframe; typeerror; function-definition; Share. A list object is mutable however, because it can change (as shown by the sort function, which permanently rearranges the list) which means that it isn't hashable so doesn't work with set. Sorted by: 3. Hashability makes an. unhashable type: 'dict' Of course can manually unpack each with loops to dfs and join and transform to a flat one, but I had a feeling there a way to do it with less fuss. also a good explanation from a kind mate: " but I think the reason for lists not working is the following. You need to use a hashable collection instead, like a tuple. Mark. if value not in self. Akasurde changed the title TypeError: unhashable type: 'list' delegate_to: fails with "TypeError: unhashable type: 'list'" Jul 28, 2018. Follow edited May 23, 2017 at 12:02. Series). Pandas: Unhashable type list Hot Network Questions Is the expectation of a random vector multiplied by its transpose equal to the product of the expectation of the vector and that of the transpose Fix TypeError: unhashable type: ‘list’ in Python . That's fine and all but following the official tutorial (found here) the code doesn't run properly. _dict: TypeError: unhashable type: 'StyleProxy' in python. the list of reference and `candidate' dispaled as below. TypeError: unhashable type: 'slice' 14. For hashing an object it. Import系(ImportError) ImportError: No module named そんなモジュールねーよ！どうなってんだ！ Attribute系(AttributeError) AttributeError: 'X' object has no. One approach that solves this in linear time is to serialize items with serializers such as pickle so that unhashable objects such as lists can be added to a set for de-duplication, but since sets are unordered in Python and you apparently want the output to be in the original insertion order, you can use dict. In other words, unless you really really really know what you are. As you already know list is a mutable Python object. import pickle. tolist () array = [tuple (i) for i in temp] This should create the input in the required format. com The Python TypeError: unhashable type: 'list' usually means that a list is being used as a hash argument. dict, list, set are all inherently mutable and therefore unhashable. As the program expects array to be a list of 2d hashable types (2d tuples), its best if you convert array to that form, before calling any function on it. TypeError: unhashable type: 'list' Is there any way around this. ndarray' when trying to create scatter plot from dataset. 2. How can I merge rows in pandas Dataframes when the value of a cell in a particular column is same. The correct way to generate the list of dicts would be to pass just the coroutines to gather, await the results, and process them into a new dict: async def get_all_details (): category_list = await get_categories () details_list = await asyncio. An unhashable type is any data type or object in Python that cannot be hashed. Connect and share knowledge within a single location that is structured and easy to search. iloc () I'm currently doing some AI research for a project and for that I have to get used to a framework called "Pytorch". TypeError: unhashable type: 'list' I've tried for over an hour to try to troubleshoot this error, but haven't. Connect and share knowledge within a single location that is structured and easy to search. Sets are a datatype that allows you to store other immutable types in an unsorted way. (Column C should be excluded for explosion for one of its elements has different size)For a current research project, I am planning to read the JSON object "Main_Text" within a pre-defined time range on basis of Python/Pandas. schema import CreateSequence, DDL db_session = sessionmaker (bind= {your database engine}) class. schemes you call return color[style] with style equal to this list, which cannot. items (): keys. If the dict you wish to use as key consists of only immutable values, you. The idea is that I analyse a set of facial features from a prepared. ・リストを集合型のキーとして使用している？. How to lemmatize a list of sentences. 6 or above Sqlalchemy does not support auto increment for oracle 11g. then, i check the type of reference and candidate, both from the original code and the modified, it return the same type list. items ()) for d in l}] The strategy is to convert the list of dictionaries to a list of tuples where the tuples contain the items of the dictionary. 3. 4. Since you are not modifying the lists, but only slicing, you may pass tuples, which are hashable. dumps (temp_dict, default = date_handler) Otherwise, if l_user_type_data is a string for the key,. 6. Jump to solution. The goal is to look at the correlation between the different categories and the target variable. As a solution, simply add the lists together before trying to apply FreqDist, like so: allWords = [] for wordList in words: allWords += wordList FreqDist (allWords) A more complete revision to do what you would like. We are passing a list as 4th key. 99% time saved. JDiMatteo JDiMatteo. Here i am using two functions for copying and pasting some required range of cells from one position to another and want to copy the. e. unhashable type nested list into a set Like above, We can convert the nested list into the tuple. The original group pipes is shadowed by the list of pipes and creating a new Pipe object fails: pipes = [Pipe ()] Use different names for the group and the list. if you are using "oracle 11g" then use following code: from sqlalchemy import event from sqlalchemy. A list can contain duplicate elements. del dic [value] Using List/Tuple/etc. Follow edited Nov 7, 2016 at 17:54. dumps() :2. . It is showing "TypeError: unhashable type: 'list'" though. A list can contain different data types and other container objects such as a list, tuple, set, or dictionary. Mi-Creativity. But you can just use a tuple instead. Since it is unhashable, a Series object is not a good fit for any of these. . See full list on pythonpool. The easiest way to fix the TypeError: unhashable type: 'list' is to use a hashable tuple instead of a non-hashable list as a dictionary key. . All we need to do is to use the hashable type object instead of unhashable types. dict. Follow edited May 23, 2017 at 12:09. そのエラー(おそらく正確にはTypeError: unhashable type: 'numpy. In simple terms, if you use a list as a key in the dictionary, you will encounter a. replace('. Unhashable type list errors; Options. The solution to this is to convert the list objects to. It also defines an eq and a hash method. TypeError: unhashable type: 'numpy. _domainOfVariable[tuple(var)] = copy. Values. 7 dictionaries are considered ordered data. If use sheet_name=None then get dictionary of DataFrames for each sheetname with keys by sheetname texts. 10 environment on Windows. Since list is mutable and not hashable, it can't be used for grouping operations. These objects must be immutable, meaning they can’t be changed,. 1 Answer. ・ハッシュ化できない？. The frozendict is a quick pip install frozendict away, and for a list where the order does not matter we can use the built-in type frozenset. python. but it has an error: TypeError: unhashable type: 'list'. After it, we can easily convert the outer list into a set python object. kind {‘quicksort’, ‘mergesort’, ‘heapsort’, ‘stable’}, default ‘quicksort’Python初学者之TypeError: unhashable type: 'list' 创建一个比较复杂的参数的时候，将参数定义成了一个字典，然后格式化了一下，报错TypeError: unhashable type: 'list'Teams. Why are slice objects not hashable in python. To get nunique or unique in a pandas. Index values are not assigned to dictionaries. list s are mutable and therefore cannot be hashed. Related. most probably self. read() data2 = infile2. Learn more about TeamsAssuming each element in new_list_of_dict has one key-value pair:. product. Only hashable objects can be keys in a dictionary. The next time you look up the object, the dictionary will try to look it up by the old hash value, which is not relevant anymore. list s are not hashable (as they are mutable), thus you can't use drop_duplicates on them directly. 12. You cannot use a list to index a dictionary, so this: del dic [v] will fail. It must be a nuance related to importing from files. _unique_items =. So you rather want call something like (i don't know what menas your args variable) So you rather want call something like (i. output1 = set (row for row in newList2 if row not in oldList1) output2 = set (row for row in oldList1 if row not in newList2) If row is of type list , then you should also convert it to tuple before putting in the set . "TypeError: unhashable type: 'list'" yet I'm trying to only slice the value of the list, not use the list itself. TypeError: unhashable type:. Hashable objects, on the other hand, are a type of object that you can call hash () on. When I run that function in a separate script using the ChessPlayerProfile dictionary it seems to work fine. Follow edited Nov 17, 2022 at 20:04. Hot Network Questions Implementation of recursive `ls` utility"TypeError: unhashable type: 'list'" What's wrong? python; pandas; Share. Learn more about TeamsUnhashable type 'list' when using list comprehension in python [closed] Ask Question Asked 5 years, 6 months ago. cache def return_a_list(n): re. Data columns. Learn more about TeamsThat weird number (3675389749896195359) represents the hash value of the string Trey in my Python interpreter. ? [. drop_duplicates hashes the objects to keep track of which ones have been seen or not, efficiently. asked Nov 15, 2022 at 14:37. 1. DataFrame'> RangeIndex: 4637 entries, 0 to 4636. A list is a mutable type, and cannot be used as a key in a dictionary (it could change in-place making the key no longer locatable in the internal hash table of the dictionary). 16. len () == 0). Why Python TypeError: unhashable type: 'list' Hot Network Questions How would computers develop in a society where a Cherokee-like language is the dominant lingua franca?In this article we will we looking the Python exception TypeError: Unhashable Type: ‘slice’. The docs say:. sum ()Error: unhashable type: 'dict' with Django and API data. The name gives away the purpose of a slice: it is “a slice” of a sequence. Since list is mutable and not hashable, it can't be used for grouping operations.