# scipy/scipy

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 """Dictionary Of Keys based matrix""" from __future__ import division, print_function, absolute_import __docformat__ = "restructuredtext en" __all__ = ['dok_matrix', 'isspmatrix_dok'] import functools import operator import numpy as np from scipy.lib.six import zip as izip, xrange from scipy.lib.six import iteritems from .base import spmatrix, isspmatrix from .sputils import (isdense, getdtype, isshape, isintlike, isscalarlike, upcast, upcast_scalar, IndexMixin, get_index_dtype) try: from operator import isSequenceType as _is_sequence except ImportError: def _is_sequence(x): return (hasattr(x, '__len__') or hasattr(x, '__next__') or hasattr(x, 'next')) class dok_matrix(spmatrix, IndexMixin, dict): """ Dictionary Of Keys based sparse matrix. This is an efficient structure for constructing sparse matrices incrementally. This can be instantiated in several ways: dok_matrix(D) with a dense matrix, D dok_matrix(S) with a sparse matrix, S dok_matrix((M,N), [dtype]) create the matrix with initial shape (M,N) dtype is optional, defaulting to dtype='d' Attributes ---------- dtype : dtype Data type of the matrix shape : 2-tuple Shape of the matrix ndim : int Number of dimensions (this is always 2) nnz Number of nonzero elements Notes ----- Sparse matrices can be used in arithmetic operations: they support addition, subtraction, multiplication, division, and matrix power. Allows for efficient O(1) access of individual elements. Duplicates are not allowed. Can be efficiently converted to a coo_matrix once constructed. Examples -------- >>> from scipy.sparse import * >>> from scipy import * >>> S = dok_matrix((5,5), dtype=float32) >>> for i in range(5): >>> for j in range(5): >>> S[i,j] = i+j # Update element """ def __init__(self, arg1, shape=None, dtype=None, copy=False): dict.__init__(self) spmatrix.__init__(self) self.dtype = getdtype(dtype, default=float) if isinstance(arg1, tuple) and isshape(arg1): # (M,N) M, N = arg1 self.shape = (M, N) elif isspmatrix(arg1): # Sparse ctor if isspmatrix_dok(arg1) and copy: arg1 = arg1.copy() else: arg1 = arg1.todok() if dtype is not None: arg1 = arg1.astype(dtype) self.update(arg1) self.shape = arg1.shape self.dtype = arg1.dtype else: # Dense ctor try: arg1 = np.asarray(arg1) except: raise TypeError('invalid input format') if len(arg1.shape) != 2: raise TypeError('expected rank <=2 dense array or matrix') from .coo import coo_matrix d = coo_matrix(arg1, dtype=dtype).todok() self.update(d) self.shape = arg1.shape self.dtype = d.dtype def getnnz(self): return dict.__len__(self) nnz = property(fget=getnnz) def __len__(self): return dict.__len__(self) def get(self, key, default=0.): """This overrides the dict.get method, providing type checking but otherwise equivalent functionality. """ try: i, j = key assert isintlike(i) and isintlike(j) except (AssertionError, TypeError, ValueError): raise IndexError('index must be a pair of integers') if (i < 0 or i >= self.shape[0] or j < 0 or j >= self.shape[1]): raise IndexError('index out of bounds') return dict.get(self, key, default) def __getitem__(self, index): """If key=(i,j) is a pair of integers, return the corresponding element. If either i or j is a slice or sequence, return a new sparse matrix with just these elements. """ i, j = self._unpack_index(index) i_intlike = isintlike(i) j_intlike = isintlike(j) if i_intlike and j_intlike: # Scalar index case i = int(i) j = int(j) if i < 0: i += self.shape[0] if i < 0 or i >= self.shape[0]: raise IndexError('index out of bounds') if j < 0: j += self.shape[1] if j < 0 or j >= self.shape[1]: raise IndexError('index out of bounds') return dict.get(self, (i,j), 0.) elif ((i_intlike or isinstance(i, slice)) and (j_intlike or isinstance(j, slice))): # Fast path for slicing very sparse matrices i_slice = slice(i, i+1) if i_intlike else i j_slice = slice(j, j+1) if j_intlike else j i_indices = i_slice.indices(self.shape[0]) j_indices = j_slice.indices(self.shape[1]) i_seq = xrange(*i_indices) j_seq = xrange(*j_indices) newshape = (len(i_seq), len(j_seq)) newsize = _prod(newshape) if len(self) < 2*newsize and newsize != 0: # Switch to the fast path only when advantageous # (count the iterations in the loops, adjust for complexity) # # We also don't handle newsize == 0 here (if # i/j_intlike, it can mean index i or j was out of # bounds) return self._getitem_ranges(i_indices, j_indices, newshape) i, j = self._index_to_arrays(i, j) if i.size == 0: return dok_matrix(i.shape, dtype=self.dtype) min_i = i.min() if min_i < -self.shape[0] or i.max() >= self.shape[0]: raise IndexError('index (%d) out of range -%d to %d)' % (i.min(), self.shape[0], self.shape[0]-1)) if min_i < 0: i = i.copy() i[i < 0] += self.shape[0] min_j = j.min() if min_j < -self.shape[0] or j.max() >= self.shape[1]: raise IndexError('index (%d) out of range -%d to %d)' % (j.min(), self.shape[1], self.shape[1]-1)) if min_j < 0: j = j.copy() j[j < 0] += self.shape[1] newdok = dok_matrix(i.shape, dtype=self.dtype) for a in xrange(i.shape[0]): for b in xrange(i.shape[1]): v = dict.get(self, (i[a,b], j[a,b]), 0.) if v != 0: dict.__setitem__(newdok, (a, b), v) return newdok def _getitem_ranges(self, i_indices, j_indices, shape): # performance golf: we don't want Numpy scalars here, they are slow i_start, i_stop, i_stride = map(int, i_indices) j_start, j_stop, j_stride = map(int, j_indices) newdok = dok_matrix(shape, dtype=self.dtype) for (ii, jj) in self.keys(): # ditto for numpy scalars ii = int(ii) jj = int(jj) a, ra = divmod(ii - i_start, i_stride) if a < 0 or a >= shape[0] or ra != 0: continue b, rb = divmod(jj - j_start, j_stride) if b < 0 or b >= shape[1] or rb != 0: continue dict.__setitem__(newdok, (a, b), dict.__getitem__(self, (ii, jj))) return newdok def __setitem__(self, index, x): if isinstance(index, tuple) and len(index) == 2: # Integer index fast path i, j = index if (isintlike(i) and isintlike(j) and 0 <= i < self.shape[0] and 0 <= j < self.shape[1]): v = np.asarray(x, dtype=self.dtype) if v.ndim == 0 and v != 0: dict.__setitem__(self, (int(i), int(j)), v[()]) return i, j = self._unpack_index(index) i, j = self._index_to_arrays(i, j) if isspmatrix(x): x = x.toarray() # Make x and i into the same shape x = np.asarray(x, dtype=self.dtype) x, _ = np.broadcast_arrays(x, i) if x.shape != i.shape: raise ValueError("shape mismatch in assignment") if np.size(x) == 0: return min_i = i.min() if min_i < -self.shape[0] or i.max() >= self.shape[0]: raise IndexError('index (%d) out of range -%d to %d)' % (i.min(), self.shape[0], self.shape[0]-1)) if min_i < 0: i = i.copy() i[i < 0] += self.shape[0] min_j = j.min() if min_j < -self.shape[0] or j.max() >= self.shape[1]: raise IndexError('index (%d) out of range -%d to %d)' % (j.min(), self.shape[1], self.shape[1]-1)) if min_j < 0: j = j.copy() j[j < 0] += self.shape[1] dict.update(self, izip(izip(i.flat, j.flat), x.flat)) if 0 in x: zeroes = x == 0 for key in izip(i[zeroes].flat, j[zeroes].flat): if dict.__getitem__(self, key) == 0: # may have been superseded by later update del self[key] def __add__(self, other): # First check if argument is a scalar if isscalarlike(other): res_dtype = upcast_scalar(self.dtype, other) new = dok_matrix(self.shape, dtype=res_dtype) # Add this scalar to every element. M, N = self.shape for i in xrange(M): for j in xrange(N): aij = self.get((i, j), 0) + other if aij != 0: new[i, j] = aij # new.dtype.char = self.dtype.char elif isinstance(other, dok_matrix): if other.shape != self.shape: raise ValueError("matrix dimensions are not equal") # We could alternatively set the dimensions to the largest of # the two matrices to be summed. Would this be a good idea? res_dtype = upcast(self.dtype, other.dtype) new = dok_matrix(self.shape, dtype=res_dtype) new.update(self) for key in other.keys(): new[key] += other[key] elif isspmatrix(other): csc = self.tocsc() new = csc + other elif isdense(other): new = self.todense() + other else: raise TypeError("data type not understood") return new def __radd__(self, other): # First check if argument is a scalar if isscalarlike(other): new = dok_matrix(self.shape, dtype=self.dtype) # Add this scalar to every element. M, N = self.shape for i in xrange(M): for j in xrange(N): aij = self.get((i, j), 0) + other if aij != 0: new[i, j] = aij elif isinstance(other, dok_matrix): if other.shape != self.shape: raise ValueError("matrix dimensions are not equal") new = dok_matrix(self.shape, dtype=self.dtype) new.update(self) for key in other: new[key] += other[key] elif isspmatrix(other): csc = self.tocsc() new = csc + other elif isdense(other): new = other + self.todense() else: raise TypeError("data type not understood") return new def __neg__(self): new = dok_matrix(self.shape, dtype=self.dtype) for key in self.keys(): new[key] = -self[key] return new def _mul_scalar(self, other): res_dtype = upcast_scalar(self.dtype, other) # Multiply this scalar by every element. new = dok_matrix(self.shape, dtype=res_dtype) for (key, val) in iteritems(self): new[key] = val * other return new def _mul_vector(self, other): # matrix * vector result = np.zeros(self.shape[0], dtype=upcast(self.dtype,other.dtype)) for (i,j),v in iteritems(self): result[i] += v * other[j] return result def _mul_multivector(self, other): # matrix * multivector M,N = self.shape n_vecs = other.shape[1] # number of column vectors result = np.zeros((M,n_vecs), dtype=upcast(self.dtype,other.dtype)) for (i,j),v in iteritems(self): result[i,:] += v * other[j,:] return result def __imul__(self, other): if isscalarlike(other): # Multiply this scalar by every element. for (key, val) in iteritems(self): self[key] = val * other # new.dtype.char = self.dtype.char return self else: raise NotImplementedError def __truediv__(self, other): if isscalarlike(other): res_dtype = upcast_scalar(self.dtype, other) new = dok_matrix(self.shape, dtype=res_dtype) # Multiply this scalar by every element. for (key, val) in iteritems(self): new[key] = val / other # new.dtype.char = self.dtype.char return new else: return self.tocsr() / other def __itruediv__(self, other): if isscalarlike(other): # Multiply this scalar by every element. for (key, val) in iteritems(self): self[key] = val / other return self else: raise NotImplementedError # What should len(sparse) return? For consistency with dense matrices, # perhaps it should be the number of rows? For now it returns the number # of non-zeros. def transpose(self): """ Return the transpose """ M, N = self.shape new = dok_matrix((N, M), dtype=self.dtype) for key, value in iteritems(self): new[key[1], key[0]] = value return new def conjtransp(self): """ Return the conjugate transpose """ M, N = self.shape new = dok_matrix((N, M), dtype=self.dtype) for key, value in iteritems(self): new[key[1], key[0]] = np.conj(value) return new def copy(self): new = dok_matrix(self.shape, dtype=self.dtype) new.update(self) return new def getrow(self, i): """Returns a copy of row i of the matrix as a (1 x n) DOK matrix. """ out = self.__class__((1, self.shape[1]), dtype=self.dtype) for j in range(self.shape[1]): out[0, j] = self[i, j] return out def getcol(self, j): """Returns a copy of column j of the matrix as a (m x 1) DOK matrix. """ out = self.__class__((self.shape[0], 1), dtype=self.dtype) for i in range(self.shape[0]): out[i, 0] = self[i, j] return out def tocoo(self): """ Return a copy of this matrix in COOrdinate format""" from .coo import coo_matrix if self.nnz == 0: return coo_matrix(self.shape, dtype=self.dtype) else: idx_dtype = get_index_dtype(maxval=max(self.shape[0], self.shape[1])) data = np.asarray(_list(self.values()), dtype=self.dtype) indices = np.asarray(_list(self.keys()), dtype=idx_dtype).T return coo_matrix((data,indices), shape=self.shape, dtype=self.dtype) def todok(self,copy=False): if copy: return self.copy() else: return self def tocsr(self): """ Return a copy of this matrix in Compressed Sparse Row format""" return self.tocoo().tocsr() def tocsc(self): """ Return a copy of this matrix in Compressed Sparse Column format""" return self.tocoo().tocsc() def toarray(self, order=None, out=None): """See the docstring for `spmatrix.toarray`.""" return self.tocoo().toarray(order=order, out=out) def resize(self, shape): """ Resize the matrix in-place to dimensions given by 'shape'. Any non-zero elements that lie outside the new shape are removed. """ if not isshape(shape): raise TypeError("dimensions must be a 2-tuple of positive" " integers") newM, newN = shape M, N = self.shape if newM < M or newN < N: # Remove all elements outside new dimensions for (i, j) in list(self.keys()): if i >= newM or j >= newN: del self[i, j] self._shape = shape def _list(x): """Force x to a list.""" if not isinstance(x, list): x = list(x) return x def isspmatrix_dok(x): return isinstance(x, dok_matrix) def _prod(x): """Product of a list of numbers; ~40x faster vs np.prod for Python tuples""" if len(x) == 0: return 1 return functools.reduce(operator.mul, x)
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