Source code for kwarray.util_numpy

"""
Numpy specific extensions
"""
import numpy as np


[docs] def boolmask(indices, shape=None): """ Constructs an array of booleans where an item is True if its position is in ``indices`` otherwise it is False. This can be viewed as the inverse of :func:`numpy.where`. Args: indices (NDArray): list of integer indices shape (int | tuple): length of the returned list. If not specified the minimal possible shape to incoporate all the indices is used. In general, it is best practice to always specify this argument. Returns: NDArray[Any, Int]: mask - mask[idx] is True if idx in indices Example: >>> indices = [0, 1, 4] >>> mask = boolmask(indices, shape=6) >>> assert np.all(mask == [True, True, False, False, True, False]) >>> mask = boolmask(indices) >>> assert np.all(mask == [True, True, False, False, True]) Example: >>> import kwarray >>> import ubelt as ub # NOQA >>> indices = np.array([(0, 0), (1, 1), (2, 1)]) >>> shape = (3, 3) >>> mask = kwarray.boolmask(indices, shape) >>> result = ub.urepr(mask, with_dtype=0) >>> print(result) np.array([[ True, False, False], [False, True, False], [False, True, False]]) """ indices = np.asanyarray(indices) if indices.dtype.kind not in {'i', 'u'}: indices = indices.astype(int) if shape is None: shape = indices.max() + 1 mask = np.zeros(shape, dtype=bool) if mask.ndim > 1: mask[tuple(indices.T)] = True else: mask[indices] = True return mask
[docs] def iter_reduce_ufunc(ufunc, arrs, out=None, default=None): """ constant memory iteration and reduction Applys ufunc from left to right over the input arrays Args: ufunc (Callable): called on each pair of consecutive ndarrays arrs (Iterator[NDArray]): iterator of ndarrays default (object): return value when iterator is empty Returns: NDArray: if len(arrs) == 0, returns ``default`` if len(arrs) == 1, returns arrs[0], if len(arrs) >= 2, returns ufunc(...ufunc(ufunc(arrs[0], arrs[1]), arrs[2]),...arrs[n-1]) Example: >>> arr_list = [ ... np.array([0, 1, 2, 3, 8, 9]), ... np.array([4, 1, 2, 3, 4, 5]), ... np.array([0, 5, 2, 3, 4, 5]), ... np.array([1, 1, 6, 3, 4, 5]), ... np.array([0, 1, 2, 7, 4, 5]) ... ] >>> memory = np.array([9, 9, 9, 9, 9, 9]) >>> gen_memory = memory.copy() >>> def arr_gen(arr_list, gen_memory): ... for arr in arr_list: ... gen_memory[:] = arr ... yield gen_memory >>> print('memory = %r' % (memory,)) >>> print('gen_memory = %r' % (gen_memory,)) >>> ufunc = np.maximum >>> res1 = iter_reduce_ufunc(ufunc, iter(arr_list), out=None) >>> res2 = iter_reduce_ufunc(ufunc, iter(arr_list), out=memory) >>> res3 = iter_reduce_ufunc(ufunc, arr_gen(arr_list, gen_memory), out=memory) >>> print('res1 = %r' % (res1,)) >>> print('res2 = %r' % (res2,)) >>> print('res3 = %r' % (res3,)) >>> print('memory = %r' % (memory,)) >>> print('gen_memory = %r' % (gen_memory,)) >>> assert np.all(res1 == res2) >>> assert np.all(res2 == res3) """ # Get first item in iterator try: initial = next(arrs) except StopIteration: return default # Populate the outvariable if specified otherwise make a copy of the first # item to be the output memory if out is not None: out[:] = initial else: out = initial.copy() # Iterate and reduce for arr in arrs: ufunc(out, arr, out=out) return out
[docs] def isect_flags(arr, other): """ Check which items in an array intersect with another set of items Args: arr (NDArray): items to check other (Iterable): items to check if they exist in arr Returns: NDArray: booleans corresponding to arr indicating if any item in other is also contained in other. Example: >>> arr = np.array([ >>> [1, 2, 3, 4], >>> [5, 6, 3, 4], >>> [1, 1, 3, 4], >>> ]) >>> other = np.array([1, 4, 6]) >>> mask = isect_flags(arr, other) >>> print(mask) [[ True False False True] [False True False True] [ True True False True]] """ flags = iter_reduce_ufunc(np.logical_or, (arr == item for item in other)) if flags is None: flags = np.zeros(arr.shape, dtype=bool) return flags
[docs] def atleast_nd(arr, n, front=False): r""" View inputs as arrays with at least n dimensions. Args: arr (ArrayLike): An array-like object. Non-array inputs are converted to arrays. Arrays that already have n or more dimensions are preserved. n (int): number of dimensions to ensure front (bool): if True new dimensions are added to the front of the array. otherwise they are added to the back. Defaults to False. Returns: NDArray : An array with ``a.ndim >= n``. Copies are avoided where possible, and views with three or more dimensions are returned. For example, a 1-D array of shape ``(N,)`` becomes a view of shape ``(1, N, 1)``, and a 2-D array of shape ``(M, N)`` becomes a view of shape ``(M, N, 1)``. See Also: numpy.atleast_1d, numpy.atleast_2d, numpy.atleast_3d Example: >>> n = 2 >>> arr = np.array([1, 1, 1]) >>> arr_ = atleast_nd(arr, n) >>> import ubelt as ub # NOQA >>> result = ub.urepr(arr_.tolist(), nl=0) >>> print(result) [[1], [1], [1]] Example: >>> n = 4 >>> arr1 = [1, 1, 1] >>> arr2 = np.array(0) >>> arr3 = np.array([[[[[1]]]]]) >>> arr1_ = atleast_nd(arr1, n) >>> arr2_ = atleast_nd(arr2, n) >>> arr3_ = atleast_nd(arr3, n) >>> import ubelt as ub # NOQA >>> result1 = ub.urepr(arr1_.tolist(), nl=0) >>> result2 = ub.urepr(arr2_.tolist(), nl=0) >>> result3 = ub.urepr(arr3_.tolist(), nl=0) >>> result = '\n'.join([result1, result2, result3]) >>> print(result) [[[[1]]], [[[1]]], [[[1]]]] [[[[0]]]] [[[[[1]]]]] Note: Extensive benchmarks are in kwarray/dev/bench_atleast_nd.py These demonstrate that this function is statistically faster than the numpy variants, although the difference is small. On average this function takes 480ns versus numpy which takes 790ns. """ arr_ = np.asanyarray(arr) ndims = len(arr_.shape) if n is not None and ndims < n: # append the required number of dimensions to the front or back if front: expander = (None,) * (n - ndims) + (Ellipsis,) else: expander = (Ellipsis,) + (None,) * (n - ndims) arr_ = arr_[expander] return arr_
[docs] def argmaxima(arr, num, axis=None, ordered=True): """ Returns the top ``num`` maximum indicies. This can be significantly faster than using argsort. Args: arr (NDArray): input array num (int): number of maximum indices to return axis (int | None): axis to find maxima over. If None this is equivalent to using arr.ravel(). ordered (bool): if False, returns the maximum elements in an arbitrary order, otherwise they are in decending order. (Setting this to false is a bit faster). TODO: - [ ] if num is None, return arg for all values equal to the maximum Returns: NDArray Example: >>> # Test cases with axis=None >>> arr = (np.random.rand(100) * 100).astype(int) >>> for num in range(0, len(arr) + 1): >>> idxs = argmaxima(arr, num) >>> idxs2 = argmaxima(arr, num, ordered=False) >>> assert np.all(arr[idxs] == np.array(sorted(arr)[::-1][:len(idxs)])), 'ordered=True must return in order' >>> assert sorted(idxs2) == sorted(idxs), 'ordered=False must return the right idxs, but in any order' Example: >>> # Test cases with axis >>> arr = (np.random.rand(3, 5, 7) * 100).astype(int) >>> for axis in range(len(arr.shape)): >>> for num in range(0, len(arr) + 1): >>> idxs = argmaxima(arr, num, axis=axis) >>> idxs2 = argmaxima(arr, num, ordered=False, axis=axis) >>> assert idxs.shape[axis] == num >>> assert idxs2.shape[axis] == num """ # if axis is not None: # raise NotImplementedError('axis must be None for now') # Gets top N maximum or minimum indices if num < 0: raise IndexError if axis is None: axis_size = arr.size if num == 0: return np.empty(0, dtype=int) elif num == 1: # very fast idxs = np.array([arr.argmax(axis=axis)]) elif num < axis_size: # argpartition is almost what we want, and its faster than argsort kth = axis_size - num part_idxs = np.argpartition(arr, kth=kth, axis=axis) idxs = part_idxs[kth:] if ordered: sortx = arr.take(idxs, axis=axis).argsort()[::-1] idxs = idxs.take(sortx) else: # sort all the indices if ordered: idxs = arr.argsort(axis=axis) idxs = idxs[::-1][0:num] else: # Arbitrary order is allowed, so cheat idxs = np.arange(arr.size) else: axis_size = arr.shape[axis] if num == 0: new_shape = list(arr.shape) new_shape[axis] = 0 return np.empty(new_shape, dtype=int) elif num == 1: newshape = list(arr.shape) newshape[axis] = 1 idxs = arr.argmax(axis=axis).reshape(*newshape) elif num < axis_size: # TODO: is there a better implementation for this case? kth = axis_size - num part_idxs = np.argpartition(arr, kth=kth, axis=axis) fancy_index = [slice(None)] * (axis + 1) fancy_index[axis] = slice(kth, None) idxs = part_idxs[tuple(fancy_index)] if ordered: # move the axis of interest to the back idxs_swap = idxs.swapaxes(-1, axis) idxs2d = idxs_swap.reshape(-1, num) arr2d = arr.swapaxes(-1, axis).reshape(-1, arr.shape[axis]) # now ensure each row is in order new_idxs2d = [] for a, i in zip(arr2d, idxs2d): sortx = a[i].argsort()[::-1] new_idxs2d.append(i[sortx]) new_idxs2d = np.array(new_idxs2d) # transform back to original shape idxs = new_idxs2d.reshape(*idxs_swap.shape).swapaxes(-1, axis) else: # sort all the indices if ordered: idxs = arr.argsort(axis=axis) fancy_index = [slice(None)] * (axis + 1) fancy_index[axis] = slice(None, None, -1) idxs = idxs[tuple(fancy_index)] else: # Arbitrary order is allowed, so cheat idxs = np.arange(arr.shape[axis]) newshape = [1] * len(arr.shape) newshape[axis] = arr.shape[axis] repeats = list(arr.shape) repeats[axis] = 1 idxs = np.tile(idxs.reshape(*newshape), repeats) return idxs
[docs] def argminima(arr, num, axis=None, ordered=True): """ Returns the top ``num`` minimum indicies. This can be significantly faster than using argsort. Args: arr (NDArray): input array num (int): number of minimum indices to return axis (int|None): axis to find minima over. If None this is equivalent to using arr.ravel(). ordered (bool): if False, returns the minimum elements in an arbitrary order, otherwise they are in ascending order. (Setting this to false is a bit faster). Example: >>> arr = (np.random.rand(100) * 100).astype(int) >>> for num in range(0, len(arr) + 1): >>> idxs = argminima(arr, num) >>> assert np.all(arr[idxs] == np.array(sorted(arr)[:len(idxs)])), 'ordered=True must return in order' >>> idxs2 = argminima(arr, num, ordered=False) >>> assert sorted(idxs2) == sorted(idxs), 'ordered=False must return the right idxs, but in any order' Example: >>> # Test cases with axis >>> from kwarray.util_numpy import * # NOQA >>> arr = (np.random.rand(3, 5, 7) * 100).astype(int) >>> # make a unique array so we can check argmax consistency >>> arr = np.arange(3 * 5 * 7) >>> np.random.shuffle(arr) >>> arr = arr.reshape(3, 5, 7) >>> for axis in range(len(arr.shape)): >>> for num in range(0, len(arr) + 1): >>> idxs = argminima(arr, num, axis=axis) >>> idxs2 = argminima(arr, num, ordered=False, axis=axis) >>> print('idxs = {!r}'.format(idxs)) >>> print('idxs2 = {!r}'.format(idxs2)) >>> assert idxs.shape[axis] == num >>> assert idxs2.shape[axis] == num >>> # Check if argmin argrees with -argmax >>> idxs3 = argmaxima(-arr, num, axis=axis) >>> assert np.all(idxs3 == idxs) Example: >>> arr = np.arange(20).reshape(4, 5) % 6 >>> argminima(arr, axis=1, num=2, ordered=False) >>> argminima(arr, axis=1, num=2, ordered=True) >>> argmaxima(-arr, axis=1, num=2, ordered=True) >>> argmaxima(-arr, axis=1, num=2, ordered=False) """ if axis is not None: # TODO: implement this directly for argminima # if 0: # return argmaxima(-arr, num=num, axis=axis, ordered=ordered) # # raise NotImplementedError('axis must be None for now, can use argmaxima(-arr) with axis in the meantime') # raise NotImplementedError('probably need to switch some cases') axis_size = arr.shape[axis] if num == 0: new_shape = list(arr.shape) new_shape[axis] = 0 return np.empty(new_shape, dtype=int) elif num == 1: newshape = list(arr.shape) newshape[axis] = 1 idxs = arr.argmin(axis=axis).reshape(*newshape) elif num < axis_size: # TODO: is there a better implementation for this case? kth = num argmin_slice = slice(0, kth) part_idxs = np.argpartition(arr, kth=kth, axis=axis) fancy_index = [slice(None)] * (axis + 1) fancy_index[axis] = argmin_slice idxs = part_idxs[tuple(fancy_index)] if ordered: # move the axis of interest to the back idxs_swap = idxs.swapaxes(-1, axis) idxs2d = idxs_swap.reshape(-1, num) arr2d = arr.swapaxes(-1, axis).reshape(-1, arr.shape[axis]) # now ensure each row is in order new_idxs2d = [] for a, i in zip(arr2d, idxs2d): sortx = a[i].argsort()[::+1] new_idxs2d.append(i[sortx]) new_idxs2d = np.array(new_idxs2d) # transform back to original shape idxs = new_idxs2d.reshape(*idxs_swap.shape).swapaxes(-1, axis) else: # sort all the indices if ordered: idxs = arr.argsort(axis=axis) fancy_index = [slice(None)] * (axis + 1) fancy_index[axis] = slice(None, None, +1) idxs = idxs[tuple(fancy_index)] else: # Arbitrary order is allowed, so cheat idxs = np.arange(arr.shape[axis]) newshape = [1] * len(arr.shape) newshape[axis] = arr.shape[axis] repeats = list(arr.shape) repeats[axis] = 1 idxs = np.tile(idxs.reshape(*newshape), repeats) else: # Gets top N maximum or minimum indices if num < 0: raise IndexError elif num == 0: return np.empty(0, dtype=int) elif num == 1: # very fast idxs = np.array([arr.argmin(axis=axis)]) elif num < len(arr): # argpartition is almost what we want, and its faster than argsort kth = num part_idxs = np.argpartition(arr, kth=kth, axis=axis) idxs = part_idxs[:kth] if ordered: sortx = arr.take(idxs, axis=axis).argsort() idxs = idxs.take(sortx) else: # sort all the indices if ordered: idxs = arr.argsort(axis=axis)[0:num] else: # Arbitrary order is allowed, so cheat idxs = np.arange(arr.size) return idxs
# def unique_axis(arr, axis): # """ # Like unique and unique_rows, but looks over any single axis # Args: # axis (int): axis to consider as a whole unit # References: # https://stackoverflow.com/questions/16970982/find-unique-rows-in-numpy-array # >>> import kwarray # rng = kwarray.ensure_rng(0) # arr = rng.randint(0, 2, size=(2, 2, 3, 2, 2)).T # axis = 2 # """ # raise NotImplementedError # orig_shape = arr.shape # axis_len = arr.shape[axis] # dtype_view = np.dtype((np.void, arr.dtype.itemsize * axis_len)) # arr_swap = arr.swapaxes(axis, 0) # arr_swap_flat = arr_swap.reshape(axis_len, -1).T # arr_swap_view = np.ascontiguousarray(arr_swap).view(dtype_view) # arr_swap_view_unique = np.unique(arr_swap_view) # arr_swap_unique = arr_swap_view_unique.view(arr.dtype) # arr_unique = # arr_swap_unique.reshape(-1, axis_len).T # # return ( # # .reshape(-1, arr.shape[1]) # # )
[docs] def unique_rows(arr, ordered=False, return_index=False): """ Like unique, but works on rows Args: arr (NDArray): must be a contiguous C style array ordered (bool): if true, keeps relative ordering References: https://stackoverflow.com/questions/16970982/find-unique-rows-in-numpy-array Example: >>> import kwarray >>> from kwarray.util_numpy import * # NOQA >>> rng = kwarray.ensure_rng(0) >>> arr = rng.randint(0, 2, size=(22, 3)) >>> arr_unique = unique_rows(arr) >>> print('arr_unique = {!r}'.format(arr_unique)) >>> arr_unique, idxs = unique_rows(arr, return_index=True, ordered=True) >>> assert np.all(arr[idxs] == arr_unique) >>> print('arr_unique = {!r}'.format(arr_unique)) >>> print('idxs = {!r}'.format(idxs)) >>> arr_unique, idxs = unique_rows(arr, return_index=True, ordered=False) >>> assert np.all(arr[idxs] == arr_unique) >>> print('arr_unique = {!r}'.format(arr_unique)) >>> print('idxs = {!r}'.format(idxs)) """ dtype_view = np.dtype((np.void, arr.dtype.itemsize * arr.shape[1])) arr_view = arr.view(dtype_view) if ordered: arr_view_unique, idxs = np.unique(arr_view, return_index=True) idxs.sort() arr_flat_unique = arr_view[idxs].view(arr.dtype) # arr_flat_unique = arr_view_unique.view(arr.dtype) arr_unique = arr_flat_unique.reshape(-1, arr.shape[1]) # arr_unique = arr_unique[np.argsort(idxs)] # arr_unique = arr_unique[np.argsort(idxs)] else: if return_index: arr_view_unique, idxs = np.unique(arr_view, return_index=True) else: arr_view_unique = np.unique(arr_view) arr_flat_unique = arr_view_unique.view(arr.dtype) arr_unique = arr_flat_unique.reshape(-1, arr.shape[1]) if return_index: return arr_unique, idxs else: return arr_unique
[docs] def arglexmax(keys, multi=False): """ Find the index of the maximum element in a sequence of keys. Args: keys (tuple): a k-tuple of k N-dimensional arrays. Like np.lexsort the last key in the sequence is used for the primary sort order, the second-to-last key for the secondary sort order, and so on. multi (bool): if True, returns all indices that share the max value Returns: int | NDArray[Any, Int] : either the index or list of indices Example: >>> k, N = 100, 100 >>> rng = np.random.RandomState(0) >>> keys = [(rng.rand(N) * N).astype(int) for _ in range(k)] >>> multi_idx = arglexmax(keys, multi=True) >>> idxs = np.lexsort(keys) >>> assert sorted(idxs[::-1][:len(multi_idx)]) == sorted(multi_idx) Benchark: >>> import ubelt as ub >>> k, N = 100, 100 >>> rng = np.random >>> keys = [(rng.rand(N) * N).astype(int) for _ in range(k)] >>> for timer in ub.Timerit(100, bestof=10, label='arglexmax'): >>> with timer: >>> arglexmax(keys) >>> for timer in ub.Timerit(100, bestof=10, label='lexsort'): >>> with timer: >>> np.lexsort(keys)[-1] """ # Handle keys in reverse order to be consistent with np.lexsort reverse_keys = keys[::-1] arr = reverse_keys[0] breakers = reverse_keys[1:] # Look for the maximum value in the first array, and continue using new # arrays until a unique maximum index is found. _cand_idxs = np.where(arr == arr.max())[0] if len(_cand_idxs) > 1: for breaker in breakers: vals = breaker[_cand_idxs] _cand_idxs = _cand_idxs[vals == vals.max()] if len(_cand_idxs) == 1: break # If multiple maximum values are found then either # return them all or return an arbitrary one. return _cand_idxs if multi else _cand_idxs[0]
# def argsort_threshold(arr, threshold=None, num_top=None, descending=False): # """ # TODO: Cleanup # Find all indexes over a threshold, but always return at least the # `num_top`. # """ # import kwarray # # Find the "best" indices and their scores # sortx = arr.argsort(descending=descending) # sorted_arr = arr[sortx] # # Mark any index "better" than the score threshold # if descending: # flags = sorted_arr > threshold # else: # flags = sorted_arr < threshold # if num_top is not None: # # Always return at least `num_top` # flags[0:num_top] = True # fallback_thresh = sorted_arr[num_top - 1] # threshold = min(fallback_thresh, threshold) # top_inds = sortx[flags] # return top_inds
[docs] def generalized_logistic(x, floor=0, capacity=1, C=1, y_intercept=None, Q=None, growth=1, v=1): """ A generalization of the logistic / sigmoid functions that allows for flexible specification of S-shaped curve. This is also known as a "Richards curve" [WikiRichardsCurve]_. Args: x (NDArray): input x coordinates floor (float): the lower (left) asymptote. (Also called ``A`` in some texts). Defaults to 0. capacity (float): the carrying capacity. When C=1, this is the upper (right) asymptote. (Also called ``K`` in some texts). Defaults to 1. C (float): Has influence on the upper asymptote. Defaults to 1. This is typically not modified. y_intercept (float | None): specify where the the y intercept is at x=0. Mutually exclusive with ``Q``. Q (float | None): related to the value of the function at x=0. Mutually exclusive with ``y_intercept``. Defaults to 1. growth (float): the growth rate (also calle ``B`` in some texts). Defaults to 1. v (float): Positive number that influences near which asymptote the growth occurs. Defaults to 1. Returns: NDArray: the values for each input References: .. [WikiRichardsCurve] https://en.wikipedia.org/wiki/Generalised_logistic_function Example: >>> from kwarray.util_numpy import * # NOQA >>> # xdoctest: +REQUIRES(module:pandas) >>> import pandas as pd >>> import ubelt as ub >>> x = np.linspace(-3, 3, 30) >>> basis = { >>> # 'y_intercept': [0.1, 0.5, 0.8, -1], >>> # 'y_intercept': [0.1, 0.5, 0.8], >>> 'v': [0.5, 1.0, 2.0], >>> 'growth': [-1, 0, 2], >>> } >>> grid = list(ub.named_product(basis)) >>> datas = [] >>> for params in grid: >>> y = generalized_logistic(x, **params) >>> data = pd.DataFrame({'x': x, 'y': y}) >>> key = ub.urepr(params, compact=1) >>> data['key'] = key >>> for k, v in params.items(): >>> data[k] = v >>> datas.append(data) >>> all_data = pd.concat(datas).reset_index() >>> # xdoctest: +REQUIRES(--show) >>> # xdoctest: +REQUIRES(module:kwplot) >>> import kwplot >>> plt = kwplot.autoplt() >>> sns = kwplot.autosns() >>> plt.gca().cla() >>> sns.lineplot(data=all_data, x='x', y='y', hue='growth', size='v') Ignore: # Helper to get correct conditional forms import sympy as sym A, K, C, B, Q, v, x, y = sym.symbols('A, K, C, B, Q, v, x, y') expr = A + (K - A) / (C + Q * sym.exp(-B * x)) ** (1 / v) sym.solve(sym.Eq(expr, y).subs(dict(x=0)), Q) """ A = floor K = capacity C = C B = growth if y_intercept is not None: if Q is not None: raise AssertionError('cannot specify Q and y_intercept') Q = -C + ((A - K) / (A - y_intercept)) ** v elif Q is None: Q = 1 y = A + (K - A) / (C + Q * np.exp(-B * x)) ** (1 / v) return y
[docs] def equal_with_nan(a1, a2): """ Numpy has array_equal with ``equal_nan=True``, but this is elementwise Args: a1 (ArrayLike): input array a2 (ArrayLike): input array Example: >>> import kwarray >>> a1 = np.array([ >>> [np.nan, 0, np.nan], >>> [np.nan, 0, 0], >>> [np.nan, 1, 0], >>> [np.nan, 1, np.nan], >>> ]) >>> a2 = np.array([np.nan, 0, np.nan]) >>> flags = kwarray.equal_with_nan(a1, a2) >>> assert np.array_equal(flags, np.array([ >>> [ True, False, True], >>> [ True, False, False], >>> [ True, True, False], >>> [ True, True, True] >>> ])) """ a1, a2 = np.asarray(a1), np.asarray(a2) a1nan, a2nan = np.isnan(a1), np.isnan(a2) nan_sameness = a1nan == a2nan value_sameness = (a1 == a2) # If they are actually the same, they should be value same xor nansame. flags = value_sameness ^ nan_sameness return flags
# Backwards compat: TODO: replace with a getattr style # backwards compatibility to provide access, but warn with # a deprecation message if this version of normalize is used. from kwarray.util_robust import normalize # NOQA