# What does it mean that argument types are unaligned? **URL:** \ **Category:** Support: How do I do ...?\ **Created:** [October 18, 2023, 11:08pm UTC](https://numba.discourse.group/t/what-does-it-mean-that-argument-types-are-unaligned/2220 "2023-10-18T23:08:59Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![MLLO](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@MLLO](https://numba.discourse.group/u/MLLO)\ **Post date:** [October 18, 2023, 11:09pm UTC](https://numba.discourse.group/t/what-does-it-mean-that-argument-types-are-unaligned/2220/1 "2023-10-18T23:09:00Z")
I have the following dtype definition ```python pointDtype = np.dtype([('x', 'f4'),('y', 'f4'),('z', 'f4')]) pointNBtype = nb.from_dtype(pointDtype) ``` and the following function, ```python @njit(nb.bool_(pointNBtype, pointNBtype)) def equal(p0, p1): return p0.x == p1.x and p0.y == p1.y and p0.z == p1.z ``` After I created the following, ```python p0 = np.array((1,2,0), dtype= pointNBtype) p1 = np.array((0,0,0), dtype= pointNBtype) ``` I get the following error, ```auto 00 args = [self.typeof_pyval(a) for a in args] 701 msg = ("No matching definition for argument type(s) %s" 702 % ', '.join(map(str, args))) --> 703 raise TypeError(msg) TypeError: No matching definition for argument type(s) unaligned array(Record(x[type=float32;offset=0],y[type=float32;offset=4],z[type=float32...more stuff ``` This runs fine **IF** i do not specify the signature (ie. `@njit` without any signature specs) ---
**Author:** ![nelson2005](https://yyz2.discourse-cdn.com/free1/user_avatar/numba.discourse.group/nelson2005/32/47_2.png) [@nelson2005](https://numba.discourse.group/u/nelson2005)\ **Post date:** [October 19, 2023, 1:53am UTC](https://numba.discourse.group/t/what-does-it-mean-that-argument-types-are-unaligned/2220/2 "2023-10-19T01:53:54Z")
Why not leave out the signature, call the function, then print out the deduced nopython signature? ---
**Author:** ![MLLO](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@MLLO](https://numba.discourse.group/u/MLLO)\ **Post date:** [October 19, 2023, 2:06am UTC](https://numba.discourse.group/t/what-does-it-mean-that-argument-types-are-unaligned/2220/3 "2023-10-19T02:06:56Z")
Thanks @nelson2005 I believe that I did that but I was still unsuccessful. Here if I run the following, ```auto pointNBtype ``` I get the following signature, ```auto Record([('x', {'type': float32, 'offset': 0, 'alignment': None, 'title': None, }), ('y', {'type': float32, 'offset': 4, 'alignment': None, 'title': None, }), ('z', {'type': float32, 'offset': 8, 'alignment': None, 'title': None, })], 12, False) ``` After running the function I posted with p0, p1 as defined above. I get the following _nonpython\_signatures_ ```auto [(Array(Record([('x', {'type': float32, 'offset': 0, 'alignment': None, 'title': None, }), ('y', {'type': float32, 'offset': 4, 'alignment': None, 'title': None, }), ('z', {'type': float32, 'offset': 8, 'alignment': None, 'title': None, })], 12, False), 0, 'C', False, aligned=False), Array(Record([('x', {'type': float32, 'offset': 0, 'alignment': None, 'title': None, }), ('y', {'type': float32, 'offset': 4, 'alignment': None, 'title': None, }), ('z', {'type': float32, 'offset': 8, 'alignment': None, 'title': None, })], 12, False), 0, 'C', False, aligned=False)) -> bool] ``` The only difference I see is that the first one does not start with `Array’ and I am not entirely certain why that is? ---
**Author:** ![nelson2005](https://yyz2.discourse-cdn.com/free1/user_avatar/numba.discourse.group/nelson2005/32/47_2.png) [@nelson2005](https://numba.discourse.group/u/nelson2005)\ **Post date:** [October 19, 2023, 2:40am UTC](https://numba.discourse.group/t/what-does-it-mean-that-argument-types-are-unaligned/2220/4 "2023-10-19T02:40:27Z")
Maybe I’m missing something, but p0 and p1 look to me like they are arrays? ---
**Author:** ![MLLO](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@MLLO](https://numba.discourse.group/u/MLLO)\ **Post date:** [October 19, 2023, 2:47am UTC](https://numba.discourse.group/t/what-does-it-mean-that-argument-types-are-unaligned/2220/5 "2023-10-19T02:47:07Z")
@nelson2005 I see what you mean. But wouldn’t p0, p1 be records here??? they were defined as `pointNBtype` which is what I used when specifying my signature. ---
**Author:** ![nelson2005](https://yyz2.discourse-cdn.com/free1/user_avatar/numba.discourse.group/nelson2005/32/47_2.png) [@nelson2005](https://numba.discourse.group/u/nelson2005)\ **Post date:** [October 19, 2023, 2:55am UTC](https://numba.discourse.group/t/what-does-it-mean-that-argument-types-are-unaligned/2220/6 "2023-10-19T02:55:28Z")
They’re arrays of pointNBtype, right? Suppose you used dtype=float. What type would you expect p0 to be? ---
**Author:** ![MLLO](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@MLLO](https://numba.discourse.group/u/MLLO)\ **Post date:** [October 19, 2023, 2:58am UTC](https://numba.discourse.group/t/what-does-it-mean-that-argument-types-are-unaligned/2220/7 "2023-10-19T02:58:01Z")
I see it now… I was confused thinking that the dtype was actually the array. However, if I change the signature to the following, ```auto @njit(nb.bool_(pointNBtype[::1], pointNBtype[::1])) ``` that should be the same as the one provided by `.nopython_signatures` but it still blows us. Just a different error. ```auto [...] TypingError: Failed in nopython mode pipeline (step: nopython frontend) No conversion from array(bool, 1d, C) to bool for '$98return_value.1', defined at None ``` ---
**Author:** ![nelson2005](https://yyz2.discourse-cdn.com/free1/user_avatar/numba.discourse.group/nelson2005/32/47_2.png) [@nelson2005](https://numba.discourse.group/u/nelson2005)\ **Post date:** [October 19, 2023, 3:06am UTC](https://numba.discourse.group/t/what-does-it-mean-that-argument-types-are-unaligned/2220/8 "2023-10-19T03:06:50Z")
Your function does operations on arrays, and returns an array, right? Is there some reason you don’t want to use the automatically deduced signature? ---
**Author:** ![MLLO](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@MLLO](https://numba.discourse.group/u/MLLO)\ **Post date:** [October 19, 2023, 3:10am UTC](https://numba.discourse.group/t/what-does-it-mean-that-argument-types-are-unaligned/2220/9 "2023-10-19T03:10:13Z")
Hi @nelson2005, that is an appropriate comment. I am transforming a long program by rewriting all the functions I have to be used with numba in order to optimize it. So… I thought better to specify as much as I can. But it might just be that I don’t really need to. ---
**Author:** ![nelson2005](https://yyz2.discourse-cdn.com/free1/user_avatar/numba.discourse.group/nelson2005/32/47_2.png) [@nelson2005](https://numba.discourse.group/u/nelson2005)\ **Post date:** [October 19, 2023, 3:12am UTC](https://numba.discourse.group/t/what-does-it-mean-that-argument-types-are-unaligned/2220/10 "2023-10-19T03:12:11Z")
Right - the general recommendation as I understand it is to let numba figure out the signature unless you have a particular reason to specify it. Even then, an inferred signature is a great place to start. ---
**Author:** ![MLLO](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@MLLO](https://numba.discourse.group/u/MLLO)\ **Post date:** [October 19, 2023, 3:14am UTC](https://numba.discourse.group/t/what-does-it-mean-that-argument-types-are-unaligned/2220/11 "2023-10-19T03:14:42Z")
It will certainly make life easier ! Thanks for your help! ---
**Author:** ![Oyibo](https://avatars.discourse-cdn.com/v4/letter/o/4af34b/32.png) [@Oyibo](https://numba.discourse.group/u/Oyibo)\ **Post date:** [October 19, 2023, 6:57am UTC](https://numba.discourse.group/t/what-does-it-mean-that-argument-types-are-unaligned/2220/12 "2023-10-19T06:57:58Z")
Hey @MLLO , If you want to compare structured arrays for equality you can use the function `np.array_equal` to check the underlying data. If you want to compare single records for equality you can use their field names as attributes. What are the benefits to use structured instead of standard arrays in your case? ```auto import numpy as np import numba as nb record_type = np.dtype([('x', 'f4'), ('y', 'f4'), ('z', 'f4')]) #============================================================================= # This defines a 0-dimensional array of record_type not a record #============================================================================= mypoint = np.array((0,0,0), dtype=np.dtype([('x', 'f4'), ('y', 'f4'), ('z', 'f4')])) print(f'type: {type(mypoint)}, ndim: {mypoint.ndim}') # type: , ndim: 0 #============================================================================= # Compare arrays #============================================================================= @nb.njit def equal_arrays(p0, p1): return np.array_equal(p0.view(np.float32), p1.view(np.float32)) p0 = np.array([(0,0,0), (1,0,0)], dtype=record_type) p1 = np.array([(0,0,0), (1,0,0)], dtype=record_type) print(f'Arrays equal? => {equal_arrays(p0, p1)}') # Arrays equal? => True #============================================================================= # Compare records #============================================================================= @nb.njit def equal_records(p0, p1): return p0.x == p1.x and p0.y == p1.y and p0.z == p1.z points = np.array([(0,0,0), (0,0,0)], dtype=record_type) print(f'Records equal? => {equal_records(points[0], points[1])}') # Records equal? => True ``` ---
**Author:** ![MLLO](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@MLLO](https://numba.discourse.group/u/MLLO)\ **Post date:** [October 19, 2023, 6:42pm UTC](https://numba.discourse.group/t/what-does-it-mean-that-argument-types-are-unaligned/2220/13 "2023-10-19T18:42:12Z")
Thanks @Oyibo ! I am still seem to be confused about how numba and numpy structured arrays behave. Point in question (building on the point spec above) ```auto entryDtype = np.dtype([('error', 'f4'), ('triangle_id', 'i8'), ('point', pointNBtype)]) entryNBtype = nb.from_dtype(entryDtype) p0 = np.array((0,0,0), dtype= pointNBtype) entry0 = np.array((0.5, 0, p0), dtype=entryNBtype) ``` I define a numba list as such, ```auto a = nb.typed.List.empty_list(entryNBtype) ``` I try the following, ```python a.append(entry0) ``` and it blows up? There is obviously something that I am missing but can see what it is? ---
**Author:** ![nelson2005](https://yyz2.discourse-cdn.com/free1/user_avatar/numba.discourse.group/nelson2005/32/47_2.png) [@nelson2005](https://numba.discourse.group/u/nelson2005)\ **Post date:** [October 19, 2023, 8:49pm UTC](https://numba.discourse.group/t/what-does-it-mean-that-argument-types-are-unaligned/2220/14 "2023-10-19T20:49:01Z")
Complete programs are helpful for responders. In this case you’re trying to append an array to a list-of-entryNBtype? anytime you use np.array() you’re the resulting type is an array. ---
**Author:** ![MLLO](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@MLLO](https://numba.discourse.group/u/MLLO)\ **Post date:** [October 19, 2023, 9:44pm UTC](https://numba.discourse.group/t/what-does-it-mean-that-argument-types-are-unaligned/2220/15 "2023-10-19T21:44:09Z")
Hi @nelson2005 I don’t know if I fully understand you answer. I am looking to have a list that will store entries (as specified). So a list of structured numpy arrays. If that make sense. How would this be accomplished? ---
**Author:** ![MLLO](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@MLLO](https://numba.discourse.group/u/MLLO)\ **Post date:** [October 19, 2023, 10:27pm UTC](https://numba.discourse.group/t/what-does-it-mean-that-argument-types-are-unaligned/2220/16 "2023-10-19T22:27:10Z")
@Oyibo Following up on your comments… how would you generate a list and a dictionary to store as structured array as your `mypoint` in numba??? I know howI would do this if `mypoint` was defined as ```auto mypoint = np.array([(0,0,0)], dtype=record_type) ``` with square brackets. I ask this because if the latter is not possible then your second option is the one I need to adopt (though I would prefer NOT to use square brackets) ---
**Author:** ![Oyibo](https://avatars.discourse-cdn.com/v4/letter/o/4af34b/32.png) [@Oyibo](https://numba.discourse.group/u/Oyibo)\ **Post date:** [October 19, 2023, 11:25pm UTC](https://numba.discourse.group/t/what-does-it-mean-that-argument-types-are-unaligned/2220/17 "2023-10-19T23:25:14Z")
Hey @MLLO , A NumPy structured array is like a lightweight version of a DataFrame. It’s useful when you need to store data with different types in a table format. However, if you’re dealing with homogeneous data, such as point coordinates, a regular NumPy array is sufficient, too. On the other hand, if structured data storage and advanced data operations are needed, consider using a Pandas DataFrame, which offers more functionality, especially for joining data based on indices. ```auto #============================================================================= # imports #============================================================================= import numpy as np from numpy.lib import recfunctions as rfn import pandas as pd #============================================================================= # Creating a numpy array #============================================================================= numpy_array = np.arange(9, dtype=np.float32).reshape(3, 3) print("Numpy Array:") print(numpy_array) #============================================================================= # Creating a structured array #============================================================================= dtype = [('x', np.float32), ('y', np.float32), ('z', np.float32)] structured_array = rfn.unstructured_to_structured(numpy_array, dtype=dtype) print("\nStructured Array:") print(structured_array.dtype.names) print(structured_array.view(np.float32).reshape(3, 3)) #============================================================================= # Creating a pandas dataframe # ============================================================================= df = pd.DataFrame(structured_array) print("\nDataframe:") print(df) # Numpy Array: # [[0. 1. 2.] # [3. 4. 5.] # [6. 7. 8.]] # Structured Array: # ('x', 'y', 'z') # [[0. 1. 2.] # [3. 4. 5.] # [6. 7. 8.]] # Dataframe: # x y z # 0 0.0 1.0 2.0 # 1 3.0 4.0 5.0 # 2 6.0 7.0 8.0 ``` ---
**Author:** ![MLLO](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@MLLO](https://numba.discourse.group/u/MLLO)\ **Post date:** [October 19, 2023, 11:39pm UTC](https://numba.discourse.group/t/what-does-it-mean-that-argument-types-are-unaligned/2220/18 "2023-10-19T23:39:37Z")
thanks @Oyibo No I was not looking for nothing as complicated as a dataframe (another possibility would be an xarray). I am more intersected in very light data structure. In the example you produced earlier you were handling a point data type as a record without making it into an array. I was interested in that possibility (e.g. the possibility of doing a list of point records). Don’t know if this makes sense. M. ---
**Author:** ![Oyibo](https://avatars.discourse-cdn.com/v4/letter/o/4af34b/32.png) [@Oyibo](https://numba.discourse.group/u/Oyibo)\ **Post date:** [October 20, 2023, 12:11am UTC](https://numba.discourse.group/t/what-does-it-mean-that-argument-types-are-unaligned/2220/19 "2023-10-20T00:11:30Z")
Hey @MLLO , if you don’t want to define structured arrays but just single records you can use the `record` class. ```auto import numpy as np import numba as nb record_type = np.dtype([('x', 'f4'), ('y', 'f4'), ('z', 'f4')]) p0 = np.record((0,0,0), dtype=record_type) p1 = np.record((1,0,0), dtype=record_type) pointType = nb.typeof(p0) points = nb.typed.List.empty_list(pointType) points.append(p0) points.append(p1) print(points) # [(0., 0., 0.), (1., 0., 0.), ...] ``` ---
**Author:** ![MLLO](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@MLLO](https://numba.discourse.group/u/MLLO)\ **Post date:** [October 20, 2023, 12:16am UTC](https://numba.discourse.group/t/what-does-it-mean-that-argument-types-are-unaligned/2220/20 "2023-10-20T00:16:52Z")
Perfect! @Oyibo I have used a lot of numpy but never used this! Thank you.