DOK¶
-
class
sparse.
DOK
(shape, data=None, dtype=None, fill_value=None)[source]¶ A class for building sparse multidimensional arrays.
Parameters: - shape (tuple[int] (DOK.ndim,)) – The shape of the array.
- data (dict, optional) – The key-value pairs for the data in this array.
- dtype (np.dtype, optional) – The data type of this array. If left empty, it is inferred from the first element.
- fill_value (scalar, optional) – The fill value of this array.
-
dtype
¶ The datatype of this array. Can be
None
if no elements have been set yet.Type: numpy.dtype
-
data
¶ The keys of this dictionary contain all the indices and the values contain the nonzero entries.
Type: dict
See also
COO
- A read-only sparse array.
Examples
You can create
DOK
objects from Numpy arrays.>>> x = np.eye(5, dtype=np.uint8) >>> x[2, 3] = 5 >>> s = DOK.from_numpy(x) >>> s <DOK: shape=(5, 5), dtype=uint8, nnz=6, fill_value=0>
You can also create them from just shapes, and use slicing assignment.
>>> s2 = DOK((5, 5), dtype=np.int64) >>> s2[1:3, 1:3] = [[4, 5], [6, 7]] >>> s2 <DOK: shape=(5, 5), dtype=int64, nnz=4, fill_value=0>
You can convert
DOK
arrays toCOO
arrays, ornumpy.ndarray
objects.>>> from sparse import COO >>> s3 = COO(s2) >>> s3 <COO: shape=(5, 5), dtype=int64, nnz=4, fill_value=0> >>> s2.todense() # doctest: +NORMALIZE_WHITESPACE array([[0, 0, 0, 0, 0], [0, 4, 5, 0, 0], [0, 6, 7, 0, 0], [0, 0, 0, 0, 0], [0, 0, 0, 0, 0]])
>>> s4 = COO.from_numpy(np.eye(4, dtype=np.uint8)) >>> s4 <COO: shape=(4, 4), dtype=uint8, nnz=4, fill_value=0> >>> s5 = DOK.from_coo(s4) >>> s5 <DOK: shape=(4, 4), dtype=uint8, nnz=4, fill_value=0>
You can also create
DOK
arrays from a shape and a dict of values. Zeros are automatically ignored.>>> values = { ... (1, 2, 3): 4, ... (3, 2, 1): 0, ... } >>> s6 = DOK((5, 5, 5), values) >>> s6 <DOK: shape=(5, 5, 5), dtype=int64, nnz=1, fill_value=0.0>
Attributes
DOK.density
The ratio of nonzero to all elements in this array. DOK.ndim
The number of dimensions of this array. DOK.nnz
The number of nonzero elements in this array. DOK.size
The number of all elements (including zeros) in this array. Methods
DOK.asformat
(format)Convert this sparse array to a given format. DOK.from_coo
(x)Get a DOK
array from aCOO
array.DOK.from_numpy
(x)Get a DOK
array from a Numpy array.DOK.to_coo
()Convert this DOK
array to aCOO
array.DOK.todense
()Convert this DOK
array into a Numpy array.